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PROCEEDINGS VIIIInternational Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla SociedadMexicanadeCienciayTecnologíade SuperficiesyMaterialesA.C. Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla ORGANIZING COMMITTEE INTERNATIONAL SCIENTIFIC COMMITEE PROGRAM COMMITTEE Juan Hernández Rosas UPIITA-IPN Patricia Thiel AVS, USA Gregorio Hernández Cocoletzi IFUAP Ivan Petrov AVS, USA Servando Aguirre Tostado CIMAV Arturo Morales Acevedo CINVESTAV-IPN Emmanuel Haro Poniatowski UAM-Iztapalapa Juan Luis Peña Chapa CINVESTAV-IPN Leticia Pérez Arrieta UAZ Steven Muhl IM-UNAM Cristo Manuel Yee Rendón UAS Alvaro Pulzara Universidad Nacional de Colombia Claudia Mendoza Barrera Microna-UV José Mauricio López Romero CENAM Guillermo Santana/ IIM-UNAM LOCAL ORGANIZING COMMITTEE Jesús González Hernández CIDESI Sergio Jiménez /CINVESTAV-Qro Salvador Gallardo Hernández /CINVESTAV-DF Naboru Takeuchi/CNYN-UNAM Gregorio Hernández Cocoletzi /IF-BUAP Jesús Heiras Aguirre /CNYN-UNAM Roberto Olayo/UAM-Iztapalapa Roberto Machorro /CNYN-UNAM Wilfrido Calleja/INAOE Horacio Estrada Vázquez /CENAM Máximo López /CINVESTAV-DF Jaime Santoyo Salazar /CINVESTAV-DF Cristo Manuel Yee Rendón /UAS Citlali Sánchez Aké/CCADET-UNAM BUAP Gregorio Hernández Cocoletzi Juan Francisco Rivas Silva Pedro Hugo Hernández Tejeda Gerardo Martínez Montes Ygnacio Martínez Laguna Rosendo Lozada Morales Martha Palomino Ovando Jesús Carrillo López María de Lourdes Ruiz Peralta Mirna López Fuentes Dolores García Toral Heriberto Hernández Cocoletzi José Humberto Camacho García Ernesto Chigo Anota Alejandro Escobedo Morales Mercedes Portillo Sampedro INAOE Wilfrido Calleja Arriaga Arturo Sarmiento Reyes Luis Hernàndez Martìnez Carlos Zuñiga Islas Francisco Javier de la Hidalga Wade UAEH Ariadna Sánchez Castillo Arturo Hernández Hernández María del Pilar Gutiérrez Amador Efraín Zaleta Alejandre Lis Tamayo Rivera Víctor Hugo Pérez España Teresa Romero Cortes Jaime Alioscha Cuervo Parra Eduardo Rangel Cortes Martin Peralta Gil Pablo Antonio López Pérez L. Irais Vera Robles/UAM-Iztapalapa Sandra Rodil (IIM-UNAM), Giovanni Ramírez /Argonne National Laboratory Joaquín Oseguera Peña /ITESM Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla Dear Colleagues, From the very beginning the Annual Conference of the Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales (SMCTSM, Mexican Society of Science and Technology of Surfaces and Materials) has been an important forum used by the Mexican scientific community for the discussion of scientific and technological topics related to research in the areas of surface and materials science. The SMCTSM is celebrating its 35th anniversary and for this special occasion we are pleased to welcome you to participate in the VIII International Conference on Surface, Materials and Vacuum (ICSMV) which will held in the city of Puebla, Puebla from the 21st to the 25th of September. This year will do the works of the confereces at the Edificio Carolino facilities, an emblematic XVII building. For this anniversary the event is co-organized between the Benemérita Universidad Autónoma de Puebla, and the Instituto Nacional de Astrofísica Óptica y Electrónica. The scientific program of the Conference is divided into plenary conferences, short courses and the different symposia with oral and poster. For the VIII edition the symposiums of Biomaterials and Polymers have merged and the same has occurred for the symposiums of Photothermal and Plasma and Vacuum and we have an invited symposium of Atomic Layer Deposition. Additionally to the scientific program, there is a symposium of Popularization of Science which is a traditional forum for the bringing together of students and the general public with the work undertaken and developed within our Society. We hope that the efforts of the organizing committee, sponsors and colleagues will result in an interesting friendly meeting, providing the opportunity for closer and new interactions between researchers coming from the diverse institutions VIII ICSMV Organizing Committee SMCTSM September 2015. Puebla, Puebla, México. Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla OPENING TALK The 14-billion Year History of the Universe Leading to Modern Materials Science Joe Greene D.B. Willett Professor of Materials Science and Physics, University of Illinois Tage Erlander Professor of Physics, Linköping University, Sweden University Professor of Materials Science, National Taiwan Univ. of Science and Technology The story begins approximately 13.8 billion years ago with the Big Bang. A brief introduction will trace the evolution of the universe to what we observe today. Many of the formative events occurred in the first tiny fractions of a second (e.g., electrons, protons, and neutrons appear) to a few tens of thousands of years (elementary particles react to form the first elements which leads, in turn, to the development of stars due to local density fluctuations). Planet Earth nucleated and began to accrete interstellar debris ~4.5 billion years ago. While the lighter metal elements on earth formed primarily due to stellar supernovae explosions, the primary mechanism leading to the formation of the heavier elements has only recently been demonstrated. The first known sophisticated stone tools used by huminids, found in northern Ethiopia, date to 2.6 million years ago Gold is likely the first metal discovered by man, >11,000 years ago. However, unlike copper (Mesopotamia, ~9000 BC), bronze (Iran, ~5000 BC), and cast iron (China, ~600 BC), it was too soft for fabrication of tools and weapons. Instead, gold was used for decoration, religious artifacts, and commerce. Spectacular metal sculpting displaying very high levels of metallurgical and artistic craftsmanship have been found in Mesopotamia (S. Iraq). The earliest high-purity Au artifacts derive not from Egypt, as commonly thought, but from NE Bulgaria ~6500 y ago; however, the largest known concentration of ancient gold mines is in the Egyptian Eastern Desert. Metal extraction from ore, copper smelting, was already being carried out in the Balkans (E. Serbia and S. Bulgaria) ~7500 years ago. Gold brazing of metal parts was first reported in ~3400 BC in Sumaria. The earliest documented thin metal films were gold layers, some less than 1000 atoms thick, produced chemi-mechanically by Egyptians ~5000 years ago. Examples, gilded on copper and bronze statues and artifacts (requiring interfacial adhesion layers), were found in hewn stone pyramids dating to ~2650 BC in Saqqara. Spectacular samples of embossed gold sheets date to at least 2600 BC. Electroless gold and silver plating was developed much later by the Moche Indians of Peru in ~100 BC. Gas-phase deposition of thin layers of metal and ceramic films on bulk substrates (as used in manufacturing of today's transistors, hard discs, LED TVs, etc.) had to wait for the invention of vacuum pumps (~1650 for mechanical pumps, similar to modern bicycle pumps, but with gas flow in the opposite direction) through ~1865. The fascinating development of crystallography (Plato [Greece], 360 BC; through Kepler [Germany], 1611; Haüy [France], 1780s; and Miller [UK, 1839]), was essential for describing crystal structure in modern materials science, mineralogy, and geology. While an historical road map tracing the progress of materials technology is interesting in itself, the stories behind these developments are even more remarkable and provide insight into the evolution of scientific reasoning. 1 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla INTERNATIONAL YEAR OF LIGTH CELEBRATION TALK Light and the refracting power of matter Rubén Barrera. Instituto de Física, Universidad Autónoma de México, México In this talk I present an historical review of the development of one of the main concepts in Optics: the index of refraction. I stress the physical ideas behind this concept and also the contributions done in this issue during the Golden Age of Islamic Science, as part of the celebration of the International Year of Light 2015. 2 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla PLENARY 1 Electron Dynamics, Magnetic Impurities and the Spin-Orbit Interaction in Graphene Systems Sergio E. Ulloa Department of Physics and Astronomy and Nanoscale and Quantum Phenomena Institute Ohio University Graphene, a monoatomic layer of carbon, is perhaps the simplest and most easily available material where electrons behave as massless Dirac particles. Apart from its many promising technological applications, the study of graphene (and other layered materials) has opened a number of interesting theoretical questions: the microscopic crystalline structure requires an additional degree of freedom (the pseudo spin) that gives rise to effects such as the Klein paradox or Veselago electron lenses. This relativistic dynamics is further emphasized by the presence of an interesting relativistic effect: the spin-orbit interaction (SOI), which is present in materials that lack inversion symmetry in the lattice structure or arises from external or interfacial fields that break spatial symmetries. Although SOI is weak in natural graphene, it can be enhanced by local hybridizations with impurities by manipulation of substrates or applied gates. I will present our studies of electronic transport and Kondo screening in graphene under realistic SOI and some of its experimental observables, including birefringence in electron optics. 3 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla PLENARY 2 Design and Synthesis of Hard and Tough Coatings Yip-Wah Chung Department of Materials Science and Engineering and Mechanical Engineering Institute for Sustainability and Energy Northwestern University, Evanston, Illinois, USA Most hard coatings are made of ceramic materials and have low toughness. It is desirable to have coatings that are both hard and tough to provide superior wear performance. There are many studies reported in the literature on obtaining hard and superhard coatings. This talk will focus on strategies to increase coating toughness while maintaining hardness. Various nanocomposite and multilayer coatings were synthesized to explore three such toughening strategies: coherency strain, transformation toughening, and nanograined metals. Results demonstrate that coating systems that exploit these strategies show significantly enhanced toughness compared with those that do not. In particular, the strategy of using nanolayers of a metal with high elastic modulus alternating with spacer layers much thinner than the metal even reverses the commonly observed inverse hardness-toughness relationship. In principle, one can reach hardness values up to 10% of the elastic modulus, while attaining toughness comparable to most nanocrystalline metals. 4 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla PLENARY 3 Multiscale Biophysics: from DNA to antibodies. A synergetic approach between SPM and HPC simulations. Pedro A. Serena1, J.G. Vilhena1,2, Ruben Perez2 1 2 Instituto de Ciencia de Materiales de Madrid, CSIC, Madrid , Spain Departamento de Física Teórica de la Materia Condensada, Universidad Autónoma de Madrid, Madrid, Spain Biophysics is an intrinsically multiscale research field. Most of the large scale properties (protein-folding, self-assembly, mechanical properties, wetting) of biological media heavily depend on things that occur at atomic scale. As a result, in this field, until very recently there was a huge gap between the processes studied in a lab and the ones that theoreticians could provide a predictive-modeling input. The access to massive computational power allows the study of systems composed by tens of millions of atoms over long periods of time. As a result, it is feasible to inspect how small atomistic changes (~0.1 nm) on a given system might influence its overall behavior on a much larger scale (~100 nm). In our group we have specialized in using this ultimate multi-scale modeling tool to bring atomistic insight into the Scanning-Probe-Microscopy experiments performed by world leading SPM experimental groups on a wide variety of topics. In this study we present some results concerning the passive vertical adsorption of antibodies over an inorganic surface. In this work we have used very-large-scale molecular dynamics together with atomic-forcemicroscope experiments to show that antibodies adsorb to graphene without any protein unfolding, finding that antibodies adsorb over graphene preferentially on bioactive orientations. In addition we will present some results that explain the behavior of DNA single-base sensitive biosensors based on cantilevers. 5 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla PLENARY 4 Using Pulsed Laser Deposition to Build Active Optical Metamaterials R. Serna, J. Toudert, M. Jiménez de Castro, I. Camps, A. Mariscal and A. Cuadrado Laser Processing Group, Insituto de Optica, CSIC, Madrid (Spain) Optical metamaterials understood as materials including sub-wavelength structures will be essential for the building of the next generation of photonic devices. These metamaterials will have functionalities such as emission, switching/processing and detection of light and will operate in a wide wavelength range, from the UV to the NIR. These effective metafunctionalities can be achieved by suitably assembling active nanoscale structures with different functionalities in a single host element. I will present the methodology that we have developed in our group in order to build metamaterials based in the concept of embedding nano-scale objects into thin film oxides using pulsed laser deposition. By suitably choosing the nature/composition, morphology and size of these nanoscale objects, thin films with specific functional responses have been obtained. In this presentation I will show and discuss some examples of our recent work that include efficient nano-hybrid emitters in the near-infrared, wide band emitters in the visible, and non-conventional plasmonic components operating in the visible. 6 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla PLENARY 5 Self-assembly and surface-mediated crystallization of inorganic-organic materials Brad Chmelka Department of Chemical Engineering University of California, Santa Barbara Santa Barbara, California 93106 U.S.A. [email protected] Surfactant-directed syntheses of mesostructured inorganic materials involve coupled kinetic processes of self-assembly, cross-linking, and/or crystallization that are strongly influenced by surface effects. Self-assembly of such materials generally depends on interactions among amphiphilic surfactant species, soluble inorganic precursors, solvent, and functional guest species, which in the case of sol-gel-derived oxides, results in liquid-crystal-like mesophases. Typically, such materials are synthesized under non-equilibrium conditions, in which crosslinking of soluble inorganic oxide species occurs simultaneously with surfactant selfassembly to form mesostructured inorganic-surfactant composites with amorphous inorganic frameworks. For certain compositions and conditions, crystallization of the inorganic frameworks can also occur, leading to changes in mesostructural order that yield layered silicate or mesostructured zeolite products. The associated kinetic processes are mediated by interactions among the inorganic, solvent, surfactant, or other species, which affect the rates and selectivities by which products form, along with their resulting compositions, structures, and morphologies. The molecular-level interactions that underlie these complex interrelated processes and associated material properties have been challenging to measure, understand, and control. Nuclear magnetic resonance (NMR) spectroscopy circumvents many of the challenges by being sensitive to local atomic environments and provides information that is complementary to scattering, electron microscopy, and macroscopic property measurements. By correlating results from these different methods, new multiscale insights are obtained on the compositions, structures, and properties of surfactant-directed inorganic-organic materials and how they change with time. Recent results will be presented on the molecular interactions and influences of surface species on the self-assembly and crystallization of mesostructured silicate, borosilicate, or aluminosilicate materials, and their implications in heterogeneous catalysis. 7 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla PLENARY 6 Tribological Visions of Charles Chaplin and Richard Feynman Prof. Dr. Esteban Broitman Thin Film Physics Division, IFM, Linköping University, SE581 83 Linköping, Sweden By the end of the second industrial revolution, Charles Chapin shows in his masterpiece silent movie “Modern Times” a futuristic factory where tribological operators clean and lubricate big machines [1]. His vision probably reflects the popular belief that, in the future, macromachines will relief mankind from heavy work. That is also accounted in most of tribological studies at that time, reporting macroscale wear and lubrication. The seed idea for developing micro- and nano-machines was probably introduced in 1959 by the physicist Richard Feynman in his lecture “There’s Plenty of Room at the Bottom” [2]. He considered that direct manipulation of matter at atomic scale will be used in a near future to build tiny machines that could arrange the atoms and perform chemical synthesis by mechanical manipulation. Nowadays, micromachines in the size range of 100 nm to 100 µm, known also as MEMS (micro-electro-mechanical systems), are used in accelerometers for automotive systems, inkjet printer heads, game controllers, hard disks, and rotation sensors for smartphones. Most of commercial micromachines are designed as transducers for applications with no contact or sliding: they are either sensors or actuators. Despite of niche industrial applications with designs of more complex MEMS devices containing moving mechanical assemblies (MEMS-MMA) like micromotors, gears and levers, the commercial production of these kind of machines is inexistent. The main problem in micromachines is tribological: the presence of stiction, high friction and wear between the small components [3]. Friction becomes critical on the microscale and is one of the fundamental limitations in the design of reliable micromotors, microgenerators, and microengines. Lubrication for decreasing friction and wear in these devices is difficult, because capillary forces created by confining liquids to small geometries is in the same order of magnitude than actuation forces generated by micromachines. Therefore, only solid or vaporphase lubrication can be used. However, there are some applications like stepper motors taking advantage of friction: with step sizes on the order of 10 to 100 nm, and actuation forces in the milli-Newton scale, they could be used for positioning optical, data storage, and medical applications. In this talk, after a short historical introduction, I will focus on the main tribological challenges of sliding micromachines. Friction and lubrication of Chaplin’s macromachines and Feynman’s micromachines will be compared. Finally, I will show some present developments leading to Feynman’s vision of machines at the nanometer scale. [1] C. Chaplin, Director and actor, Modern Times. [Film], 1936. [2] R. P. Feynman, There’s Plenty of Room at the Bottom, Engineering and Science, February issue (1960) 22-36. [3] E. Broitman, The nature of the frictional force at the macro-, micro-, and nano-scales, Friction 2 (2014) 40-46. 8 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla PLENARY 7 Laser produced periodic patterns: fundamentals and applications R. J. Peláez, C. N. Afonso Laser Processing Group, Instituto de Optica, CSIC, Serrano 121, E-28006 Madrid, Spain e-mail address: [email protected] This contribution will show that laser interference is a versatile attractive tool for creating a variety of periodic micro/nano patterns that diffract light and exhibit colors. It represents a cost and time effective alternative to the very costly and multi-step lithographic methodologies. These patterns are interesting in several sectors such as photonics, consumer industry, security or solar cells as well as have a high potential as platforms for bio assays or sensing. The features and spatial limits of the patterns depend on the material properties and configuration and the pattern period and motives can be tailored to the application envisaged through a number of parameters. The underlying mechanisms as well as their time scales, the parameters playing an essential role on the process and the variety of patterns accessible will be illustrated through patterns produced on two very different materials: porous silicon layers and ultrathin metal layers having plasmonic response. Finally, the potential of some these platforms for bio assays will be illustrated through the successful alignment of cells in culture on selected patterns with high potential for tissue regeneration. 9 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla PLENARY 8 Droplet epitaxy for III-V semiconductor nanostructures Luisa González IMM-Instituto de Microelectrónica de Madrid (CNM-CSIC) The droplet epitaxy growth technique was firstly used at the beginning of the 1990s by Koguchi et al.[1]. It was proposed as a development of the molecular beam epitaxy (MBE) for the fabrication of III–V semiconductor nanostructures on II–VI semiconductor substrates with nearly equal lattice constant. It basically consists of the deposition of atoms of group-III element in absence of any supply of group-V element, creating liquid metal droplets on the substrate. These metal droplets are, right afterwards, exposed to an atmosphere of group-V element, which induces their crystallization into III–V nanostructures. This technology permits to obtain quantum nanostructures on heteroepitaxial systems with or without lattice mismatch, representing an actual advantage over well-established Stranski-Krastanow processes where the strain is the driving force for nanostructures formation Depending on the substrate temperature, this growth method yields different types of nanostructures. For example, on GaAs (001) substrates, quantum dots (QD) [2] and quantum rings (QR) complexes [3] are formed at relatively low temperatures of 200–300 C, whereas nanoholes surrounded by mounds [4, 5] are obtained at high substrate temperatures (500C). In particular these nanoholes can be used as a template to obtain both strained and strain-free QD by filling them with a semiconductor with a smaller band-gap than that of the host matrix [5]. Within this approach, the size and shape of the resulting nanostructures can be modified independently of the areal density. The simultaneous control of QD density and emission wavelength is crucial for applications as single photon emitter devices. In this paper, the potential of droplet epitaxy for nanostructures formation will be described, with emphasis on the mechanisms of nanoholes formation, mandatory in order to take advantage of all the potential of droplet epitaxy as a nano-patterning technique [6]. References [1] N. Koguchi et al., J. Cryst. Growth 111, 688–692 (1991) [2] J.S. Kim, et al., Appl. Phys. Lett. 85, 5893–5895 (2004) [3] T. Mano, et al., Nano Lett. 5, 425–428 (2005) [4] Z.M. Wang, et al., Appl. Phys. Lett. 90, 113120 (2007) [5] P. Alonso-González, et al., Appl. Phys. Lett. 91, 163104, (2007) [6] Fuster, D. et al., Nan. Res. Lett 9, 309 (2014) 10 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla PLENARY 9 Reconfigurable and Tunable photonic molecules for optical signal processing Prof. Newton C. Frateschi IFGW – UNICAMP, Brasil Optical interconnection and photonic integration are essential for the realization of the ubiquitous computing that arises from the Internet of Things (IOT) scenario. There is an urgent demand for bandwidth increase, system size reduction, all with power consumption reduction. We have recently demonstrated silicon/silica based photonic molecules, i.e., planar coupled optical resonators, for optical signal processing. In these structures, the photonic properties or optical signal processing functions are optimized by utilizing the coupled supermodes instead of a sequence of individual modes of independent resonators in the same fashion as one combines atoms to engineer molecular properties. These devices overcome the existing intrinsic interdependence between photonic lifetime, resonance spacing and footprint for single micro resonators, introducing a new degree of freedom to perform spectral engineering. Optical carrier recycling, potential for modulation beyond resonance bandwidth limit, and low-power wavelength multicasting using multiple-split resonances in micrometer-scale devices have been demonstrated. [1–3]. In this talk we will first focus on the several aspects of utilizing photonic molecules for spectral engineering with a review of the above results. Finally, we will focus on new active structures where reconfigurable and continuously tunable mode-splitting in a multi-GHz range is achieved with very low resonance shift. [4] A new class of devices is shown to provide great flexibility in designing devices for optical signal processing using very compact structures based on a CMOS compatible technology. 1. 2. 3. 4. L. A. M. Barea, F. Vallini, G. F. M. de Rezende, and N. C. Frateschi, "Spectral Engineering With CMOS Compatible SOI Photonic Molecules," IEEE Photonics J. 5, 2202717–2202717 (2013). L. A. M. Barea, F. Vallini, P. F. Jarschel, and N. C. Frateschi, "Silicon technology compatible photonic molecules for compact optical signal processing," Appl. Phys. Lett. 103, 201102 (2013). M. C. M. M. Souza, L. A. M. Barea, F. Vallini, G. F. M. Rezende, G. S. Wiederhecker, and N. C. Frateschi, "Embedded coupled microrings with high-finesse and close-spaced resonances for optical signal processing," Opt. Express 22, 10430–10438 (2014). Mario C. M. M. Souza, Guilherme F. M. Rezende, Luis A. M. Barea, Antonio A. G. von Zuben, Gustavo S. Wiederhecker, and Newton C. Frateschi, Spectral engineering with coupled microcavities: active control of resonant mode-splitting,” Optics Letters, 40 (17), pp. 3332-3335 (2015) 11 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla PLENARY 10 Functional Defects in Nanodiamond Particles: Challenges and Opportunities Gary E. McGuire and Olga A. Shenderova Adámas Nanotechnologies Inc., Raleigh, North Carolina Nanodiamond (ND) particles have recently emerged as a key platform for many sectors of nanoscience and nanotechnology due to their outstanding mechanical performance, biocompatibility and distinctive optical properties, a combination of assets not often met in the nanoworld. Two recent major breakthroughs, production of individual 4-5nm particles (single-digit NDs) and particles containing color centers exhibiting stable luminescence and unique spin properties have brought ND particles to the forefront of materials research.1 It is important to be aware, though, that the method of synthesis of NDs influence their structure (morphology, size, state of doping elements) and, therefore, their properties and niche applications. This aspect will be discussed in more details. Commercially available nanometer size particles are produced by detonation of carbon-containing explosives (called detonation nanodiamonds) or by grinding of microdiamond powders produced by phase transformation of carbon precursors under high pressure and high temperature (HPHT). While the former are a source of single-digit NDs, the latter are a basis for production of NDs containing color centers (particularly nitrogen-vacancy centers) with uniquely coupled fluorescent and spin properties. Development of multimodal imaging probes based on 510nm ND with a high density of NV centers and doping of ND with new functional elements are future directions for this field. A goal of this talk is to provide a general background on ND particles, more in-depth review of functional defects in NDs and outline current and perspective applications of ND in areas which have broad societal impact. V.Mochalin, O.Shenderova, D.Ho and Y.Gogotsi, “The properties and applications of nanodiamonds”, (2012) Nature Nanotechnology, 7 (1) 11-23. 1 12 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla PLENARY 11 Optical properties II-VI semiconductors materials O. Zelaya-Angel Department of Physics, Centro de Investigación y de Estudios Avanzados del IPN. P.O. Box 14-740, México 07560 D.F. Nanostructured samples of II-VI semiconductor compounds can be prepared in powders, thin films, rods, membranes, etc. format by means of a large variety of techniques such as: sputtering, chemical bath, and pulsed laser deposition. Binary, ternary and quaternary phases information have found many useful applications in modern industry. The more common experimental techniques employed to study the optical properties of the semiconductor materials are: Optical absorption, Raman spectroscopy, photoreflectance, and fluorescence. This information is supported by X-ray diffraction, microscope images, and electron dispersión spectroscopy. In our work, stress, phase transitions, optical band gap variations, vibrational modes shifts, electromagnetic emissions in the visible región, etc. have been studied in CdS, CdSe, CdTe, CdO, ZnS, ZnSe, ZnTe and ZnO binary sistems; and CdTeO, CdSbTe, CdInTe, etc, ternary compounds. As instance, in a zinc blende – wurtzite (cubic to hexagonal) transformation of CdS, the band gap reaches a minimum value in the critical point and the green photoluminescence band splits in two bands (yellow and green) due to a lot of Cd-interstitials generated in the transition. 13 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla COURSE A Surface Preparation for Thin Film Deposition Gary E. McGuire Adámas Nanotechnologies Inc., Raleigh, North Carolina Course Objectives: Understand the nature of surfaces (practical and technologically significant). Learn about surface preparation, sample handling, and contamination control. Develop insight into surface characterization and analysis. Learn about surface preparation and film nucleation during thin-film deposition. Course Description Substrate preparation is an integral part of any film deposition process. This includes removing unwanted impurities and residues as well as conditioning the surface to promote adhesion through activation, or interfacial layers. The selection of the cleaning and surface preparation techniques is dependent on the nature of the surface and the deposition technique. This course reviews surface cleaning and preparation techniques, condensation and nucleation of the deposited atoms, film-substrate interface formation, and the initial stages of film growth. Both wet and dry cleaning procedures will be discussed with an aim towards remove of ionic, metallic and organic residues as well as particles. Emphasis will be placed on atomistic and reactive deposition utilizing evaporation, sputtering, chemical vapor and molecular beam deposition. Film properties, such as intrinsic stress, which may affect adhesion will be reviewed. Techniques used to characterize the elemental composition, chemical state, and phase of material will be illustrated for both in situ and ex situ analysis. Who Should Attend? Scientists, engineers, technicians, supervisors, and others who are involved in the deposition of materials in vacuum or controlled ambients, and who want to learn about the effects of surface preparation and condition on the nucleation and growth of films and the subsequent interfacial adhesion and film properties. Knowledge of elemental physics and chemistry is helpful in assimilating the course material, but it is not essential. 14 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla Course B Nanostructured hard coatings and special topics on their Characterization Yip-Wah Chung Northwesthern University, USA The short course on nanostructured coatings will have two parts. The first covers enhanced hardness of nanostructured coatings, strategies to improve thermal stability, and applications in dry machining. The second part covers special topics on the characterization of such coatings, including grain size, residual stress, hardness, and fracture toughness 15 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla COURSE C Spin-Orbit Interaction in Bulk Materials, Surfaces and Two-Dimensional Crystals Sergio E. Ulloa Department of Physics and Astronomy and Nanoscale and Quantum Phenomena Institute, Ohio University, Athens, Ohio 45701, USA. This course discusses the microscopic origin of spin-orbit interaction in materials and some of its consequences on their band structure, as well as its role in determining observables that reveal the dynamics of electrons and excitons in different systems. 16 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla COURSE D Raman spectroscopy Workshop for chemical and material identification in materials research. Richard W. Bormett Renishaw Incorporated This workshop will provide a review of the theory and the application of Raman spectroscopy techniques useful to the scientific community. Raman spectroscopy has been proven to be capable of providing material and chemical analyses of samples that may vary in size from the very large to the sub-micron, and that maybe in sealed containers (under glass or plastic). New advances in technology now allow Raman microscopy to be extended from the optical microscopes to AFM and SEM microscopes. Raman imaging supports a number of “fast” chemical and topographical contrast methods that can greatly simplify area composition distribution analysis. There will be emphasis on Raman microscopy, with imaging techniques that reveal layers and material distributions, for example in cells, and advanced materials including composites. A live demonstration of Raman microscopy with 785 nm and 532 nm excitation and the imaging processing and acquisition capabilities of dispersive multi-wavelength Raman system will be available so attendees are encouraged to bring microscope compatible samples. 17 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla COURSE E Epitaxia de haces moleculares (MBE): Nanoestructuras cuánticas de semiconductores III-V Luisa González IMM-Instituto de Microelectrónica de Madrid (CNM_CSIC) http://www.imm-cnm.csic.es/mbe La epitaxia de haces moleculares (MBE) es un proceso de crecimiento que se utiliza para una gran variedad de materiales por su capacidad para producir láminas delgadas de muy alta pureza y excelente calidad cristalina. Partiendo de un sustrato monocristalino, es posible encontrar las condiciones adecuadas para que el crecimiento sea epitaxial, de modo que la estructura cristalina de la lámina esté determinada por la del sustrato. Fue utilizada por primera vez para el crecimiento de semiconductores compuestos y aún sigue siendo éste su uso más común, si bien se ha extendido a diversos sistemas materiales que incluyen óxidos y metales. El proceso MBE tiene lugar en condiciones de ultra-alto vacío y permite producir capas epitaxiales con control muy preciso en composición y dopado, así como intercaras abruptas a escala atómica. Mediante MBE se han podido realizar estructuras consideradas como modelos en física de estado sólido (pozos cuánticos QW, hilos cuánticos QWR y puntos cuánticos QD), y éstas se han utilizado para la fabricación de dispositivos de nuevo diseño, como transistores de alta movilidad, dispositivos emisores de fotones individuales, o en el desarrollo de elementos optoelectrónicos ya existentes de características avanzadas. En este curso se introducirán los conceptos básicos que definen el crecimiento epitaxial por MBE y se describirán los equipos y sus componentes. Como ejemplo de sistemas materiales crecidos por MBE, se describirá el crecimiento y propiedades de heteroestructuras de semiconductores III-V, centrándonos en nanoestructuras que presentan confinamiento cuántico (QW, QWR, QD). Se introducirán las principales técnicas de caracterización in situ y en tiempo real del proceso de crecimiento de nanoestructuras semiconductoras. Finalmente se describirán otros procesos de crecimiento epitaxial basados en MBE y algunas aplicaciones. Bibliografía Molecular beam epitaxy, Y. Cho and J. R. Arthur, Prog. Solid State Chem. 10, 157-191 Molecular beam epitaxy: applications to key materials. Robin F. C. Farrow, ed. Noyes Publications, USA, 1995 Molecular beam epitaxy, John R. Arthur, Surf. Sci. 500 (2000) 189-217 18 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla COURSE F Practical Peak-Fitting of XPS Data Alberto Herrera Gómez1, Servando Aguirre Tostado2 1 Cinvestav-Queretaro, Libramiento Norponiente 2000, Real de Juriquilla, Queretaro 76230, México 2 Centro de Investigación en Materiales Avanzados, S.C.(CIMAV), Av. Alianza Norte #202, Parque de Investigación e Innovación Tecnológica (PIIT), Nueva Carretera Aeropuerto Km. 10, Apodaca, Nuevo León, México. C. P. 66600. This short course will be aimed to providing practical tools for peak-fitting X-ray Photoelectron Spectroscopy (XPS) data. The issues that will be discussed are the following: • Simple methods for analyzing simple data. • Tools for analyzing complex data. • Background modeling. • Practical line shapes for asymmetric peaks. • The physical origin of the various elements in a spectrum. • The physical meaning of each of the parameters employed during peak-fitting. The participants will be invited to share their experiences with the technique and to bring their own data for open discussion. 19 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla TECHNICAL TALK I Diffraction and Beyond: The Modern Multipurpose Diffractometer Jorge Pablo González PANalytical Mexico Most of the laboratory diffractometers are dominated by Cu sources … but why? The modern X-ray diffractometers can analyze powder, thin films & surfaces with many more X- ray scattering techniques than just diffraction. Reflectivity it’s the first “non-diffraction” type of analysis that we can do with X-ray Diffractometers. This technique has been available on lab based diffractometers for quite a while. New two dimensional detectors can be used for GISAXS to study surface microstructure & topography to study defects on thin films. This new techniques can complement the traditional x ray analysis like x ray reflectivity & GIXRD. During this presentation we will cover how one instrument can offer these tools to get more information about thin films, nano-particles and solid materials and some In situ experiments that can be performed easily with one technology available on the Lab 20 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla TECHNICAL TALK II Avance en la Tecnología de Bombas Turbomoleculares por PFEIFFER VACUUM. . Edward Ho Pfeiffer Vacuum Temas: Turbobombas con tecnología Mag Lev y “ball bearing” Estaciones de bombeo HiCube de Pfeiffer con tecnología ACP Estaciones de bombeo con funcionamiento intermitente de "bajo nivel de ruido / operación verde". Sistemas Especializados de Pfeiffer en bombas turbomoleculares Bombas turbo HiPace ultra-alto vacío Aplicaciones móviles para bombas turbo HiPace 10 - HiPace 30 21 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla AB-INITIO CALCULATIONS AND SUPERCOMPUTING (ACS) Chairmans: Dr. Naboru Takeuchi (CNYN-UNAM), Dr. Gregorio Hernández Cocoletzi (IF-BUAP) Oral Sessions [ ACS-59 ] Density Functional Theory Study of the Organic Functionalization of Hydrogenated Graphene, Silicene and Germanene Pamela Rubio Pereda ([email protected]) 1 , Noboru Takeuchi Tan2 1 Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE) 3918, Postal Code 22860, Ensenada, Baja California, Mexico. 2 Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México, Postal Code 22800, Ensenada, Baja California, Mexico. Silicene and germanene, the silicon and germanium analogous of graphene, are two newly synthesized two-dimensional nanomaterials and as graphene, they all present unique features and promising potential applications that already have attracted worldwide attention. The organic functionalization of these nanomaterials could provide the necessary tools for the molecular level manipulations that the microelectronic industry will demand within the next decades. In particular, the organic functionalization with molecules containing unsaturated C−C bonds by means of a radical initiated reaction constitutes a favorable route for the attachment of organic layers. In this work, computer simulations were applied to model the chemical behavior of graphene, silicene and germanene hydrogen terminated surfaces towards the radical initiated reaction with acetylene, ethylene and styrene molecules. The understanding of these chemical surface reactions was studied with the use of the density functional theory. For each case, atomic structures for different stages of the reactions were optimized with the inclusion of van der Waals dispersion forces and potential energy profiles were derived to evaluate the chemical reaction performance. 22 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla Results indicate that silicene and germanene are good candidates for organic functionalization due to low activation energy barriers. Nevertheless, the hydrogenated graphene system was found to be more difficult to be organic functionalized than the other surfaces of silicene and germanene. This difference is attributed to the rather small carbon lattice structure and repulsion issues due to the similarity in the electrostatic potential between graphene and organic molecules. We acknowledge partial financial support from Conacyt project 164485-F. [ ACS-289 ] Ultrafast charge dynamics and metallic domain growth in monoclinic VO2 Jose Mario Galicia Hernandez ([email protected]) 2 , Volodymyr Turkowski 1 , Talat S. Rahman 1 , Gregorio Hernandez Cocoletzi 2 1 2 Department of Physics, UCF, 4000 Central Florida Blvd, Orlando, FL 32816, USA IFUAP, BUAP, Av. San Claudio y Blvd. 18 Sur, Col. San Manuel, Puebla, Puebla, Mexico We apply a combined time-dependent density functional theory (TDDFT) and dynamical mean-field theory (DMFT) approach to study the ultrafast response of insulating (monoclinic) vanadium dioxide (VO2) system to a perturbation by an ultrafast laser pulse. Namely, the ground state properties and the excitation energies of the system were studied by using a DFT approach followed by DMFT calculations to take into acount strong electronelectron interactions. We considered two types of perturbations: a homogeneous and a localin-space ultrafast laser pulses. The system response was calculated with TDDFT with the nonadiabatic (frequency-dependent) exchangecorrelation (XC) kernel obtained from the DMFT solution for the effective Hubbard model. We analyze the details of the dynamics of the breakdown of the metal-insulator transition and the relaxation of the system to equilibrium. In particular, in the case of local-in-space excitation we establish the time-dependence of the metallic domain size at different values of the local Coulomb repulsion and the XC kernel parameters. We demonstrate that the memory effects (time-resolved electron-electron interactions), taken into account by the nonadiabatic XC kernel, play an important role in the response of the system. 23 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla INVITED TALK [ ACS-345 ] Atomic-scale sliding friction of graphene in water Pedro Serena 1 , J.G. Vilhena 1 , Carlos Pimentel 1 , Patricia Pedraz 1 , Feng Luo 1 , Carlos Pina 1 , Enrique Gnecco 1 , Ruben Perez 1 1 Instituto de Ciencia de Materiales de Madrid (ICMM), CSIC, Madrid, Spain It is a long accepted fact that friction is a very complex process whose understanding and description is beyond the reach of classical phenomenological laws. Nevertheless only recently, advances in the measurement technologies and instrumentations allowed us to take a closer look at these processes. In particular, Atomic-Force-Microscopy has helped to reveal many new insights associated with friction at atomic-scale. Nevertheless, the interpretation of these experiments, i.e. convolution between the imaging signal and the tip/surface interactions, is far from straightforward. In vacuum, this gap was filled with moleculardynamics simulations. These allowed us to have a better understanding of the atomic scale processes/interactions occurring at the tip-surface interface, thus unlocking a new unexplored possibilities. (channel of information) of AFM. Here we report molecular-dynamics simulations in which we simulate an FFM measurement of the atomic-scale friction properties of graphene/graphite embedded in water. In our simulations we use atomistic classical potentials and Jarsynski steered molecular-dynamics methods to measure the free energy variations as we scan the surface. Taking the derivative of these free energies differences we are able to reconstruct the FFM friction force curves including entropic contributions arising from the interaction of the water molecules with the AFM tip. Our findings, not only are in excellent agreement with the experimental results, but also show how in water we can recover FFM atomic contrast, only previously obtained in ultra-high-vacuum conditions. Furthermore, our atomistically detailed simulations allow us to shed light on the origin of this outstanding resolution, in particular in the role played by the water molecules in this kind of measurements. 24 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ ACS-374 ] Fe adsorption and incorporation into the Mn3N2(001) surfaces Jonathan Guerrero-Sánchez ([email protected]) 1,3 , Andrada-Oana Mandru 3 , Noboru Takeuchi 3 , Noboru Takeuchi 2 , Gregorio H. Cocoletzi 1 , Arthur R. Smith 3 Benemérita Universidad Autónoma de Puebla, Instituto de Física “Ing Luis Rivera Terrazas”. 2 Centro de Nanociencias y Nanotecnologia, Universidad Nacional Autónoma de México. 3 Department of Physics and Astronomy, Nanoscale and Quantum Phenomena Institute. Ohio University. 1 We have investigated the Fe adsorption and incorporation in the Mn3N2(001) surfaces using first-principles spin-polarized total energy calculations. Adopting a surface formation energy criterion it is demonstrated that the Fe incorporation is energetically favorable for all surfaces. The bilayer formation is obtained when Fe replaces Mn atoms in the N-vacancy layers. The magnetic coupling shows an antiferromagnetic alignment in the z direction as that one presented by the bare surfaces. Furthermore, the in-plane magnetic coupling between Fe-Fe and Fe-Mn shows a ferromagnetic behavior in all cases. These results clearly indicate that Fe behaves in a similar fashion as Mn in the sub-surface. The stable structures density of states show a deviation from the antiferromagnetic behavior, with the Fe-d and Mn-d orbitals making the most important contribution at the vicinity of the Fermi level. [ ACS-505 ] Theoretical study of luminescence witnessed in nanostruc-tured Silicon Rich Oxide films ascribed to defects in the inter-face with silicon agglomerates Nestor Espinosa ([email protected]) 2 , David Hernández 1 , Javier Martinez 1 , Francisco Flores 1 , Alberto Luna 1 1 2 CIDS CIDS ICUAP The electrical and optical properties of Si-based materials, like Silicon Rich oxide (SRO), are of special importance for their application in optical fibers technologies, and optoelectronic devices are determined, together with other mechanisms, by local structural 25 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla defects. Thus, considerable efforts have been made in the past decades to understand the structural, optical and electronic properties of point defects in SRO. Recently, quantumchemical calculations have proved increasingly useful for the study of the structure and properties associated with point defects in amorphous isolators and semiconductors. In particular, a cluster approach based in ab initio calculus has provided several new discernments into the microstructure of local defects in SRO and it is claimed that it may a bridge the gap between the properties of isolated molecules and the condensed phase[1]. The interest about the optical properties of SRO has been increased starting from it was confirmed that SRO films exposed to high-temperature annealing exhibit efficient photoluminescence (PL) In general, luminescent properties can provide meaningful information regarding the crystalline structure of a material and, in the case of Silicon Rich Oxides thin films, their luminescence properties are on the whole important since these films can be used to fabricate luminescent devices. Recently we published the Global Reactions Model (GRM)[2] to describe a set of chemical reactions that could hypothetically occur during the process of obtaining silicon rich oxide (SRO) films, notwithstanding of the technique used to grow such films. Particularly, chemical reactions that occur during the process of growing of SRO films by Low Pressure Chemical Vapor Deposition (LPCVD) and Hot Filament Chemical Vapor Deposition (HFCVD) techniques were emphasized in these model[i]. We suggest and evaluate either some types of molecules or resulting nanostructures and we have predicted theoretically, by applying the density functional theory (DFT), the contribution that they may have to the phenomenon of luminescence. We calculated the luminescent spectra of the as grown and the annealed structures. References [1] T. Uchino. Ab initio cluster calculations on point defects in amorphous SiO2. Current Opinion in Solid State and Materials Science 5 (2001) 517–523 [2] A new Model for Prediction of luminescent comportment of nanostructured Silicon Rich Oxide. N.D. Espinosa-Torres, J.A. Luna-López, A.D. Hernández de la Luz, J.F.J. FloresGracia, J. Martínez-Juárez and G. Flores-Carrasco. International Journal of Innovative Science, Engineering and Technology. Volume 4, Issue 2, March 2015. ISSN: 2319-5967. 26 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla Poster Sesion [ ACS-26 ] Bulk Bands projected , surface states and resonant states of chrome in the crystallographic directions (001) and (110) Hernán Javier Herrera Suárez 3 , Alberto Rubio-Ponce 1 , Daniel Olguín 2 1 Departamento de Ciencias Básicas, Universidad Autónoma Metropolitana–Azcapotzalco, Av. San Pablo 180, México, D.F. 02200, México. 2 Departamento de Física, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Apartado Postal 14740, México, D.F. 07300, México. 3 Universidad de Ibagué, Facultad de Ciencias Naturales y Matemáticas, Colombia, Carrera 22 Calle 67 Barrio Ambalá. In this work we present a detailed study of the electronic band structure of the (001) and (110) of Chrome. For our study we use the tight-binding approach and the surface Green function matching method. First, we study the electronic properties of the transition metals in volume, we use tigth-binding Hamiltonians in the Slater Koster formalism (SK). We using an orthogonal atomic basis of nine spd atomic orbitals, for each atom in the unitary cell. The parameters of the model, in the two centers approach, were taken from of the handbook of electronic band structure published by Papaconstantopoulos. These parameters reproduce the electronic band structure and the total density of states properly of each one of the different studied transition metals. For the study of the surfaces we use the surface Green function matching method. We verify that the local density of states, projected in the volume, agrees with the results obtained for the infinite case reported by Papaconstantopoulos. Next, we make a detailed study of the different characteristic surface states and resonant states for the crystallographic surfaces (001) and (110). We find that our results compare acceptably well with the previous published values, and we make the prediction of new different states not yet reported in the literature. We report a catalog of these surface states. 27 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ ACS-55 ] Structural and electronic properties of Eu doped ZnO Nanorods José Luis Cervantes López ([email protected]) 2 , Ricardo Rangel Segura 2 , Donald Homero Galván Martínez 1 , Juan Francisco del Rosario Estrada Cruz 1 1 Centro de Nanociencias y Nanotecnología - UNAM, Km 107 Carretera TijuanaEnsenada, Pedregal Playitas, CP 22860, Ensenada, Baja California 2 Universidad Michoacana de San Nicolas de Hidalgo, Posgrado en Ingeniería Química, Francisco J. Mujica s/n col. Felicitas del Río, CP 58030, Morelia Michoacán, México. The synthesis of one-dimensional single crystalline ZnO nanostructures has been a growing interest, due to their promising applications in nanoscale devices. This comes from their interesting physical properties; such as wide and direct band gap, large exciton binding energy, high electron mobility and high thermal conductivity [1]. Doping ZnO with rare earth and 4d transition elements it’s an interesting technique to tune up the optical properties of ZnO. In the present work, the structural and electronic properties of ZnO and Eu-doped ZnO nanorods with hexagonal shape were investigated through of Density Functional Theory (DFT) calculated trough Local Density Approximation (LDA) and Perdew-Zunger for exchange and correlation. The relative stability after inclusion of elements into the ZnO host lattice was studied. The ground state properties, equilibrium bond lengths, and band structures of ZnO and doped-ZnO system has also been investigated. References [1] Giancarlo Cicero, Madani Samah Slimane Haffada, "Structural and electronic properties of ZnO nanowires: a theoretical study ," SciVerce Sciencedirect , no. 10, pp. 128-137, 2011. [2] Yuebin Zhang, Rong-Kun Zheng, Simon Peter Ringer and Sean Li Mohammad Hussein Naseef Assadi, "Structural and electronic properties of Eu- and Pd-doped ZnO ," Nanoscale Research Letters , 2011. [3] Anderson Janotti and Chris G Van de Walle, "Fundamentals of zinc oxide as a semiconductor," REPORTS ON PROGRESS IN PHYSICS, pp. 1-29, 2009. [4] Bin Wen, Roderick V.N. Melnik, Tingju Li Zhiwen Yang, "Geometry Dependent Current-Voltage Characteristics of ZnO Nanostructures: A Combined Nonequilibrium Green’s Function and Density Functional Theory Study ," APPLIED PHYSICS LETTERS , pp. 1921011-1921013, 2009. [5] A. L. Rosa, Th. Frauenheim, R. Q. Zhang and S. T. Lee Hu Xu, "Density-functional theory calculations of bare and passivated triangular-shaped ZnO nanowires ," APPLIED PHYSICS LETTERS , pp. 0319141-0319143, 2007. [6] Q. Jiang and G. W. Yang S. Li, "Uniaxial strain modulated band gap of ZnO nanostructures ," APPLIED PHYSICS LETTERS , no. 96, pp. 2131011-2131013, 2010. [7] Philip B. Allen, James T. Muckerman, James W. Davenport, and Jin-Cheng Zheng Xiao Shen, "Wire versus Tube: Stability of Small One-Dimensional ZnO Nanostructures ," NANO LETTERS , vol. 7, no. 8, pp. 2267-2271 , 2007. 28 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ ACS-64 ] Quantum chemical studies of biophysical systems with interest in medical applications Dolores Garcia Toral ([email protected]) 1 , María del Rosario Melchor Martínez 1 1 FIQ-BUAP Prol 14 Sur s/n Cd Universitaria, 72570 Heróica Puebla de Zaragoza, Pue. The main objective is to present a quantum chemical study for caffeine, dopamine, ephedrine, phenytoin, primidone and norepinephrine, all of these in its molecular form, which are involved in medical treatment for cardiovascular and nervous system primarily. It has a ranking of the most relevant of each of the molecules, such as electronic molecular structure as well as its use primarily physicochemical and medical and general information. The theory used for this study is based on the density functional essentially report the values of hardness and chemical softness, which were studied and were calculated for each above-mentioned structure. Displaying the results graphically and numerically in terms of the highest occupied molecular orbital and lowest unoccupied molecular orbital. [ ACS-92 ] First principles equations and chemical synthesis of yttrium oxide S. Valdez ([email protected]) 3 , I.E. Diaz Ramos 3 , S. Robles C. 4 , Ociel R.P. 3 , A. Bautista H. 2 , M.I. Pech-Canul 1 1 Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional Cinvestav-Saltillo. Coahuila 25900, Mexico 2 Fac. De Ingeniería. Benémerita Universidad Autonoma de Puebla. Apdo. Postal. J-39. Puebla Puebla. 72570 Mexico. 3 Instituto de Ciencias Físicas-UNAM Campus Morelos. Av. Universidad s/n. Col. Chamilpa. CP 62210. Cuernavaca, Morelos México 4 Universidad Autonoma del Estado de Morelos, CIICAP. Av. Universidad 1001. Col. Chamilpa. CP 62210. Cuernavaca, Morelos México. Whereas yttrium oxide is a compound having good chemical stability, high dielectric strength, and high resistance to electrochemical degradation, we have been studying their structural properties. At the theoretical level, we have applied a method for calculating the structural properties of yttrium oxide from first principles equations within the framework of 29 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla Density Functional Theory (DFT). The exchange-correlation functional used was the local density approximation (LDA). From these calculations we have determined the lattice parameter, the bulk modulus and Young's modulus. At the experimental level, we have synthesized the particles of yttrium oxide by a chemical substitution reaction between yttrium nitrate and ammonium hydroxide. The resulting precipitates of yttrium oxide were oxidized at 800 ° C. The crystal structure of the yttrium oxide powder was obtained with X-ray diffraction by the Rietveld method. The results were compared with those reported for the yttrium oxide obtained by hot isostatic pressing. [ ACS-130 ] Structural and electronic properties of doped clusters: A DFT study. David Mora-Herrera ([email protected]) 1 , Martín SalazarVillanueva 1 1 Facultad de Ingeniería, BUAP, Puebla Puebla In this work clusters of transition metals were considered with different geometries. All of them were optimized with a smart algorithm based on DFT (Density Functional Theory). The total energy, HOMO-LUMO gap and vibrational frequencies have been obtained. The HOMO-LUMO gap with Koopmans’s approximation was the criterion taken into account to establish the chemical stabilities of these systems. The electronic properties like vertical ionization potential, vertical electronic affinity and chemical hardness are discussed. 30 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ ACS-142 ] Vacancy Effects on the Electronic Properties of Silicene Nanoribbons under Strain J. Hernández-Tecorralco 2 , M. R. Chávez-Castillo ([email protected]) 1,2, L. Meza-Montes2 , M. A. Rodríguez-Meza 1 1 Instituto Nacional de Investigaciones Nucleares, Apdo. Postal 18-1027, 11801, México, D.F, México 2 Instituto de Física, Benemérita Universidad Autónoma de Puebla, Apdo. Postal J-48, 72570, Puebla, Pue., México. In the recent emergence of two-dimensional materials, scientists have shown great interest in other graphene-like systems. Despite the fact that graphene possesses extraordinary physical, chemical, and mechanical properties which make it attractive for wide range of applications in the nanotechnology field, it has the disadvantage that it may be not easily integrated with the actual silicon-based technology. Silicene, the silicon counterpart of graphene, has gained much attention due to its similarity to graphene. As a result, silicene could be used for applications not only in nano-electronics but also in nano-electromechanical systems. Since nanoribbons (NRs) exhibit different edge geometries, i. e., armchair and zig-zag chiralities, the properties could be determined by the width and chirality of the NR. Moreover, properties could be manipulated by doping, strain and defects. In this work, we study the response of electronic and mechanical properties of Silicene-NRs to the presence of a monovacancy defect. The Quantum Espresso package is employed in this study to perform calculations in the framework of Density Functional Theory method. The structural parameters, band structure, and electronic density of states are analyzed in both chirality directions in pristine and vacancy-defect Silicene-NRs without strain. As the electronic properties could be affected by strain, we performed calculations for the case when tensile strain is applied. We found our results are in good agreement with previous results for the pristine case. 31 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ ACS-160 ] First principle calculations of the disorder double perovskite Sr2FeMoO6 Abdul Mauricio Reyes Usuga ([email protected]) 1,2 , , Yesenia Arredondo León 3 , Oracio Navarro Chavéz 4 1 Unidad Morelia, Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Antigua Carretera a Pátzcuaro No. 8701, Col. Ex Hacienda de San José de la Huerta, 58190, Morelia, Michoacán, México. 2 Facultad de Ciencias Físico Matemáticas, Universidad Michoacana de San Nicolás de Hidalgo, Av. Francisco J. Mojica S/N, Ciudad Universitaria, Morelia, Michoacán, México 3 Escuela Nacional de Estudios Superiores, Unidad Morelia, Universidad Nacional Autónoma de México, Antigua Carretera a Pátzcuaro No. 8701, Col. Ex Hacienda de San José de la Huerta, 58190, Morelia, Michoacán, México. 4 Unidad Morelia, Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Antigua Carretera a Pátzcuaro No. 8701, Col. Ex Hacienda de San José de la Huerta, 58190, Morelia, Michoacán, México First principle calculations were done in the double perovskite Sr2FeMoO6 compound regarding the effects of cationic disorder and the electronic correlation in the ground-state properties like the spin polarization and the magnetic saturation. In the calculation we use the formalism given by the Generalized Gradient Approximation (GGA) including the U Hubbard term. The results show that the disorder breakdowns the half-metallic behavior of the above compound and the magnetic saturation decreases. 32 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ ACS-186 ] Ideal strength and elastic stability of InX (X=N, P, As, Sb, Bi) compounds with zinc-blende structure Juan Carlos Moreno Hernandez 2 , Jose Humberto Camacho Garcia ([email protected]) 2 , Maria de Lourdes Ruiz Peralta 2 , Alejandro Bautista Hernandez 1 , Martin Salazar Villanueva 1 1 2 FI-BUAP FIQ-BUAP In this work, we present a study of hydrostatic compression ideal strength of InX (X=N,P,As,Sb,Bi) compounds with a zinc-blende (ZB) structure by first principles calculations. Lattice parameters, bulk, shear, and Young´s modulus, are obtained in the ground state. The elastic constants are obtained as a function of applied stress. The results shows a good agreement respect to theoretical and experimental data. The ideal strength of each compound was calculated using the Born-Wang elastic stability criteria. [ ACS-222 ] First principles calculations of phenol adsorption on pristine and hydrogenated Al-doped boron nitride sheet. Yuliana Elizabeth Avila Alvarado ([email protected]) 3 , María Teresa Romero de la Cruz 2 , Gregorio Hernández Cocoletzi 1 1 Benemérita Universidad Autónoma de Puebla, Instituto de Física "Luis RiveraTerrazas" 2 Universidad Autónoma de Coahuila, Facultad de Ciencias Físico Matemáticas 3 Universidad Autónoma de Coahuila, Facultad de Ciencias Químicas First principles total energy calculations have been performed to study the structural and electronic properties of phenol adsorption on pristine (BN) and hydrogenated Al-doped (Al-BN) boron nitride sheet. Calculations have been made within the periodic density functional theory as implemented in the PWscf code of the QUANTUM ESPRESSO package. The exchangecorrelation energies were treated with the generalized gradient approximation (GGA). Electron-ion interactions were modeled with pseudopotentials. The electron states were expanded in plane waves with an energy cutoff of 30 Ry. A supercell with 4x4 periodicity was used. In addition, the non-local correlation energies were accounted using the van der Waals density functional (vdW-DF) method. The most stable configuration for BN-phenol 33 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla systems was the parallel orientation onto stacked site, in this case the molecule was placed upon N atom. For hydrogenated Al-BN phenol system, Al doping induces a strong interaction between the phenol molecule and doped layer yielding chemical adsorption. Also the electronic band structure was calculated for the most stable configurations. The BN-phenol system keeps the insulating property with an indirect band gap approximately 4.1 eV. These results are in good agreement with previous reported results. Hydrogenated Al-BN system shows a metallic behavior. [ ACS-290 ] Solving the Schrödinger Equation for the Yukawa potential in ideal circular and square Quantum Wires. Reyna Méndez Camacho ([email protected]) 2 , Ramón Castañeda Priego 1 , Esteban Cruz Hernández 2 1 2División de Ciencias e Ingenierías, Campus León, Universidad de Guanajuato, Loma del Bosque 103, León, Gto., México. 2 Coordinación para la Innovación y la Aplicación de la Ciencia y Tecnología, CIACYTUASLP, Sierra Leona 550, S. L. P., S. L. P., México. The study of one-dimensional (1D) quantum confined systems is of great importance due to both, the new phenomena triggered by the strong 1D electronic interactions and its inherent potential applications as nanowire components. Semiconductor nanowires (NWRs) are 1D emerging materials that, through controlled growth and organization, can be exploited in the fabrication of novel nanoscale photonic and electronic devices [1]. Even when electronic confinement has been theoretically studied by a variety of theoretical models and simulation methods, there is not a methodic study of the problem of two electrons interacting under a Yukawa potential, which is a potential frequently used to simplify the many-electron problem of diverse systems. In this work, we present the solution of the Schrodinger equation for the case of two electrons confined into NWRs of square and circular infinite potential barriers. Correlation degree between pair of electrons are presented as a function of the electronic shielding strength. In order to confirm the validity of our numerical method, the limit cases for the screening parameter k were evaluated to recover the limit of two electrons interacting under: a) a Coulomb potential (k tending to 0), b) into the bulk material (large cross section) and, c) free electron (k tending to infinity). We report the dependence of both the energy levels and the charge density with the geometry of the NWRs and the value of the k parameter. [1] Yat Li, Fang Qian, Jie Xiang, and Charles M. Lieber, Materials today, Vol. 9, Issue 10, (2006), 18–27. 34 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ ACS-297 ] Numerical Solution of the Schrödinger Equation for the Yukawa potential in an Al(x)Ga(1-x)As/GaAs Quantum Wire Reyna Méndez Camacho ([email protected]) 1 , Ramón Castañeda Priego 2 , Esteban Cruz Hernández 1 1 Coordinación para la Innovación y la Aplicación de la Ciencia y Tecnología, CIACYTUASLP, Sierra Leona 550, S. L. P., S. L. P., México. 2 División de Ciencias e Ingenierías, Campus León, Universidad de Guanajuato, Loma del Bosque 103, León, Gto., México. Semiconductor quantum wires (QWRs) offer many opportunities for the assembly of nanoscale electronic and optoelectronic devices. In these one-dimensional (1D) systems, discrete energy states and strong confinement of charge carriers, photons and phonons lead to unique 1D properties that have potential in a wide range of applications, such as lasers, solar cells or biological sensors. In order to deeply understand some of these unique properties, many mathematical models and simulations have been proposed. In this work we present a methodic study of the problem of two electrons into an AlxGa1-xAs/GaAs QWRs interacting under a Yukawa potential (YP). The YP has been frequently used to simplify the many-electron problem of diverse systems. In this work, we present the solution of the Schrödinger equation for the case of two electrons confined into AlxGa1-xAs/GaAs QWRs of square and circular potential barriers. The proposed model is dependent on the temperature, the Aluminium concentration (by using the Varshni model), the index of the substrate (implicit in the effective mass), the dopant level (associate at the screening parameter κ in the YP), and the cross section geometry of the QWR (circular or square). For the real case (experimental values), we take 1013-1017 e/cm3, the (631) Miller index, a temperature of T=300K, an Aluminium concentration of x=0.23, an electron-electron distance the order of the laticce parameter of the GaAs (a=0.56535nm) and a wall-electron potential in the conduction band of V=0.65 [Egap(AlxGa1xAs)-Egap(GaAs)]. We then report the dependence of both the energy levels and the charge density with the geometry of the QWRs and the value of the k parameter. 35 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ ACS-330 ] Surface modes of a negative face velocity Fibonacci multilayer structure Xóchitl Ines Saldaña Saldaña ([email protected]) 1 , Gregorio Hernández Cocoletzi 2 1 2 Instituto de Física, Benemérita Universidad Autónoma de México Instituto de Física, Benemérita Universidad Autónoma de Puebla Using the transfer matrix theory [1], we present a numerical study of the surface modes propagating at the interface of a homogeneous medium in contact with a multilayer structure constructed following the Fibonacci recurrence formula Sj+2 = Sj+1&Sj (j = 0,1,2,3,…) where & means concatenation. Here S0 = B represent a dielectric homogeneous slab with refractive index nb and thickness db and S1 = A represent a strongly anisotropic non-magnetic slab [2] constructed with nanospheroids aligned and homogeneously distributed in an isotropic dielectric host with thickness da. A criterion for the existence of the surface modes is developed and compared with the periodic case. [1] P.Yeh, Optical Waves in Layered Media, Wiley, New York (1988). [2] P. H. Hernández, G. Martínez, G. H. Cocoletzi, H. A. Coyotecatl, and J. Díaz, J. Appl. Phys. 101, p. 093103-1 (2007). Acknowledgement: Work partially supported by CA250 Materiales Avanzados, VD-BUAP, México 36 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ ACS-346 ] Molecular Dynamics Simulation of BSA Adsorption on a Stepped Graphite Surface. Yuliana Elizabeth Avila Alvarado1,2 , Pamela Rubio Pereda 1,3 , Perceval Velosillo 1 , Pedro A. Serena ([email protected]) 1 , Rubén Pérez 4 , Guilherme Vilhena1,4 , María Teresa Romero de la Cruz 2 1 Instituto de Ciencia de Materiales de Madrid, CSIC, Madrid, Spain 2 Universidad Autónoma de Coahuila, México 3 Centro de Investigación Científica y de Educación Superior de Ensenada (CICESE), Ensenada, Baja California, México 4 Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, Madrid, Spain To obtain well-ordered immobilized biomaterial arrays for the integration of bio-sensing units in the semiconductor device technology or to better comprehend protein adsorption onto implant materials based on carbon substrates, certain properties of the substrate surfaces such as surface topography, play a major role in biomedical engineering and biotechnology applications. One main topographical feature is the presence of surface atomic-level structures that in contact with protein solutions of different concentrations show, in accordance with SPM studies, that protein adsorption occurs preferentially along step edges, where a higher chemical reactivity is expected. To address this problem, we have studied the adsorption of the model globular protein BSA onto a graphene surface with topographic features via molecular-dynamics atomistic simulations. The level of detail in our simulations such as the inclusion of explicit solvent, physiological ion concentrations and long time dynamics, allow us to address with better detail this mechanism. Results show that initial protein diffusion toward substrate occurs much faster with the presence of surface atomiclevel structures, followed by an initial biased protein diffusion when adsorbed onto atomic structures with sizes over 10 Å height due to the lack of van der Waals short range interactions. Moreover the low loss in a–helical contents of BSA adsorbed supports the capability of biofunctionalization of graphene. 37 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ ACS-365 ] Ab initio calculation of the effect of Oxygen on the electronic properties of hydrogenated [110] oriented SiC Nanowires Alejandro Trejo Baños ([email protected]) 1 , José Luis Cuevas Figueroa 2 , Álvaro Miranda Durán 3 , Miguel Cruz Irisson 1 1 Instituto Politécnico Nacional, ESIME Culhuacán, Av. Santa Ana 1000 col. San Francisco Culhuacán, C.P. 04430 D. F. México 2 Universidad Autónoma Metropolitana- Xochimilco Calzada del Hueso 1100 col. Villa quietud Del. Coyoacán C. P. 04960 México D. F. 3 Universidad Nacional Autónoma de México, Instituto de Física, Apartado Postal 20-364, México D. F., México Silicon carbide nanowires (SiCNWs) have been of interest to many researchers due to their attractive properties, such as: high mechanical strength, high thermal conductivity, chemical inertness and wide gap energy for applications in electronics, optics, advanced engineering and nanoelectromechanical switches. There are some theoretical and experimental investigations of SiCNWs, mainly focused on the [001], [111] and [112] growth directions, and none about [110] oriented nanowires due to their lower stability compared to the other three directions. However, the [110] oriented SiCNWs could be interesting for applications in microelectronics due to its peculiar symmetry which is similar to a nanotube. This work studies the effects of hydrogen and Oxygen in the electronic band gap of Silicon Carbide Nanowires (SiCNW) grown in [110] direction by means of Density Functional Theory. We compare electronic properties of H passivated SiCNWs in comparison to a mixed passivation of O and H by changing some of the surface dihydrides with Si–O–Si or C–O–C bonds. The results show that regardless the diameter and passivation most of the nanowires have a direct band gap which suggest an increased optical activity. The surface C–O–C bonds reduce the electronic band gap energy compared to the H-terminated phase while the nanowires with Si–O–Si bonds have a higher band gap. The calculation of formation energies show that the oxygen increases the chemical stabilization. These results indicate the possibility of band gap engineering on SiC nanostructures through the surface passivation. 38 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ ACS-394 ] Van der Waals interactions in the organic molecules encapsulation within boron nitride zigzag nanotubes Raúl Alfonso Vazquez Nava ([email protected]) 1 , Ramsés Valente Salazar Aparicio 1 , Gregorio Hernández Cocoletzi 2 1 2 Departamento de Fotonica, Centro de Investigaciones en Óptica Instituto de Física, Benemérita Universidad Autónoma de Puebla First principles total energy calculations are performed to investigate the structural and electronic properties of the organic molecule encapsulation within boron nitride nanotubes (BNNTs) with zigzag chirality. Eight organic molecules are explored: glycine, serine, cysteine, cytosine, thymine, uracil, adenine and guanine. Three different approaches are used; Hartree-Fock, density functional theory (DFT) and DFT-D3 which includes dispersion corrections. The finite length single wall BNNTs, with (12,0) chirality, are composed of six BN bilayers which are terminated by nitrogen at one end and by boron at the other end. Hydrogen atoms are used to saturate dangling bonds. Ground states structures are reported which are used to determine the total density of states of the molecule encapsulation. Binding energies calculations show chemical interactions between the molecule and the NT. The energy gap of the bare NT is modified by the molecule encapsulation; in some cases this gap increases while it decreases in others. The change in the bandgap size is produced by the molecules and NT orbital hybridization. These results suggest the BNNT use in the drug transportation within the human body to cure diseases. 39 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ ACS-395 ] Second-harmonic generation studies of nanotubes: First principles calculations Raúl Alfonso Vázquez Nava ([email protected]) 1 , Ramses Valente Salazar Aparicio 1 , Gregorio Hernández Cocoletzi 2 1 2 Departamento de Fotonica, Centro de Investigaciones en Óptica Instituto de Física, Benemérita Universidad Autónoma de Puebla We present ab initio calculations to investigate the second harmonic generation (SHG) response of single wall zigzag nanotubes. Studies have been performed using the density functional theory (DFT) within the local-density approximation (LDA) together with the GW Green function method to determine the band gap. A length gauge approach has been used to calculate the nonlinear optical response with the scissors correction to obtain the nonlinear susceptibility of the zigzag nanotubes. Our results show that, contrary to reports in the literature, the (5,0) and (9,0) nanotubes display non vanishing SHG response. 40 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ ACS-418 ] DFT STUDY OF THE ELECTRONIC AND STRUCTURAL PROPERTIES OF A PbS QUANTUM DOTSUPPORTED TiO2 NANOPARTICLE Tania Gabriela Diaz Rodriguez ([email protected]) 1 , Jesus Muñiz Soria2 , Mauricio Pacio Castillo 1 , Hector Juarez Santiesteban 1 1 CIDS,BUAP, Ciudad Universitaria, San Manuel, Código Postal 72570, Puebla,Mexico 2 IER, UNAM, Xochicalco, Azteca, 62588 Temixco, Mor. The geometric and electronic structure were determined for a junction of two semiconductor nanoparticles: (TiO2)38[1] and PbS, with different geometries reports experimentally for PbS: Cubic and centering on plane [1 1 1][2,3]. Also different PbS stoichiometries were verified into TiO2-PbS system to find the ideal gap sizes. These predictions will be implemented in the laboratory. The structure of the ground electronic state of both nanoparticles were determined using Density Functional Theory (DFT) calculations using FHI-AIMS[4] package. The densities of states (DOS) of these particles were calculated in vacuum. Next the atomic and electronic structure of their junction was determined. The calculations were performed at the level of DFT, using a plane-wave basis set, and the generalized gradient approximation (GGA) of Perdew-Burke-Ernzerhof for the exchangecorrelation energy [5]. The core electrons were described with Projector Augmented Wave (PWA) method, also were included relativistic scalars effects (ZORA)[6] and Van Der Waals interactions using Tkatchenko-Scheffler methodology[7]. Since the photocatalytic activity of a system is determined by its atomic and electronic structures the results derived here provide fundamental data to develop and design photocatalytic systems for hydrogen production. [1]Xiabo Chen, Semiconductor-based Photocatalytic Hydrogen Generation, Chem. Rev., 110 (2010). [2] K. Donghun, Impact of Stoichiometry on the Electronic Structure of PbS Quantum Dots,Phys. Rev. Lett., (2013). [3] B. Kiran, (PbS)32:A baby crystal,J. Chem. Phys., (2012). [4]. V. Blum, R. Gehrke, F. Hanke, P. Havu, V. Havu, X. Ren, K. Reuter, M. Scheffler. Comp. Phys. Comm. 180 (2009), 2175. [5] J.P Perdew,Generalized Gradient Approximation Made Simple, Phys. Rev. Lett., (1996). [6]R. Ahuja, A. Blomqvist, P. Larsson, P. Pyykkö, and P. Zaleski-Ejgierd, Relativity and the Lead-Acid Battery. Physical Review Letters 106, 018301 (2011). [7]. A. Tkatchenko and M. Scheffler, PRL 102, 073005 (2009) 41 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ ACS-452 ] DFT study of the interaction of amine group with aflatoxin B1 Luis Angel Juárez-Morales 1 , Heriberto Hernández-Cocoletzi ([email protected]) 1 , Eva Águila-Almanza 1 , Ernesto Chigo-Anota 1 1 Facultad de Ingeniería Química, BUAP, Av. San Claudio y 18 sur S/N CU, San Manuel Edif. 106A, C. P. 72570 Puebla México Contamination by aflatoxin B1 (AfB1) affects food, especially cereal grains. Depending on the exposition time the AfB1 may be carcinogenic, hepatotoxic, and teratogenic1. It is produced by the Aspergillus flavus and Aspergillus parasiticus fungi2. To prevent damages associated with AfB1 it is necessary its isolation and/or its mitigation. There are different approaches to face the problem, ranging from the physical separation of contaminated grains to chemical treatments; the nixtamilizacion process is also considered a good option. The former has led to the fungus and/or aflatoxin more resistant, requiring larger amounts or concentrations, giving rise to some damage to the grain and eventually to humans and animals, including the environment. Recently it has been shown that synthetic chitosan is able to inhibit the growth of both the AfB 1 and the fungus that produces it3. There is an increasing interest on the use of antifungal compounds obtained from natural resources such as chitosan obtained from shrimp exoskeletons4, which is non-toxic, biodegradable, biocompatible3 and it has low cost. It has been shown experimentally that chitosan adsorb AfB15; however, it is not known if the adsorption is chemical or physical, important feature for separation process. The amine group of chitosan plays the fundamental role in the interaction, then, a theoretical study is required. In this work we show that amine group is physically adsorbed on AfB 1 by using a DFT study. The GAUSSIAN 09 code is employed. 1. Kannewischer I., Tenorio A. M. G., White G. N., y Dixon J. B. (2006). Clay Science, Japan. vol. 12(2):99-204. 2. Guzman de Peña D. (2005). Rev. Lat. de Microb. vol. 47(3-4):160-164. 3. Cota A. O., Cortez R. M. O., Rosas B. E. C., Burgos H. A., López F. Y. L. y Plascencia J. M. (2011). Polymer International. vol. 40: 937-944. 4. Hernández C. H., Águila A. E., Flores A. O., Viveros N. E.L. y Ramos C. E. (2009). Sup. y Vac., vol. 22(3):57-60. 5. Balseca-López D. M., Hernández-Cocoletzi H., Tenorio-Arvide M. G., Aguila6. Almanza E., Esparza-Ibarra E., Revista Latinoamericana el Ambiente y las Ciencias, 6, (2015) 2784. Acknowledgements: This work has been partially supported by VIEP-BUAP. 42 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ ACS-482 ] Indigo and dehidroindigo encapsulation in palygorskite clay: An ab initio study with VDW-DF interactions Francisco Sánchez Ochoa ([email protected]) 3 , Gregorio Hernández Cocoletzi 3 , Gabriel Iván Canto Santana 1 , Noboru Takeuchi Tan 2 1 Centro de Investigación en Corrosión, Universidad Autónoma de Campeche, 24039 Campeche, México. 2 Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México, Km 107 Carretera Tijuana-Ensenada, CP. 22800 Ensenada, B.C, México. 3 Instituto de Física, Benemérita Universidad Autónoma de Puebla, Apartado Postal J48, 72570 Puebla, México. In this work we perform ab-initio calculations to investigate the structural, binding and electronic properties of palygorskite clay housing organic molecules such as indigo (IND) and dehidroindigo (DHI). This system is the well-known Maya blue pigment. Studies are performed within the periodic density functional theory. The electron-ion interactions are treated with pseudopotentials, and the exchange-correlation energies are modeled according to the VDW-DF functional. Studies start by determining the structural parameters of the pure paligorskite (Pbmn) clay and the isolated molecules, IND and DHI. The nano-hybrid IND/DHI@clay was modeled with 1x1x3 and 1x1x5 supercells where the organic dyes are housed. Binding energy profiles are calculated for the diffusion of dye(s) through the nanotúnel with and without zeolitic water molecules in the same tunnel. Additionally we have determined the total density of states and the partial density of states for the most stable structures to show that, the electronic properties around the Fermi level are governed by the guest dyes. Finally, charge density differences show the redistribution of charge when the dispersion effect is included in the VDW-DF exchange-correlation functional. 43 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla ATOMIC LAYER DEPOSITION(ALD) Chairman: Pierre Giovanni Mani González (UACJ) Oral Session [ ALD-58 ] Chirality in Amino Acid Overlayers on Cu Surfaces Leonardo Morales de la Garza ([email protected]) 1 , David A. King 2 , Stephen M. Driver 2 , Miriam L. Clegg 2 1 Universidad Nacional Autónoma de México, Centro de Nanociencias y Nanotecnología. Apdo. Postal 14, Ensenada, Baja California, MÉXICO, 22800. 2 University of Cambridge, Department of Chemistry. Cambridge CB2 1EW, UK Chirality at surfaces has become a strong focus within the surface science community. A particular motivation is the prospect of using heterogeneous catalysis over chiral solid surfaces for asymmetric synthesis, a prospect which has clear relevance to the pharmaceutical industry. Small amino acids adsorbed on Cu surfaces have emerged as important model systems for studying the interaction of chiral molecules with metal surfaces. We review the current state of knowledge of these systems, and present the results of new experimental studies of alanine overlayers on Cu{311} and {531} surfaces. Our work on Cu{311} helps us to understand the interplay between different manifestations of chirality, especially ‘‘footprint chirality’’, in the overlayers. Cu{531} is an intrinsically chiral surface orientation; our data reveal strongly enantiospecific alanine-induced restructuring of this surface. This points the way towards a promising route for obtaining strongly enantiospecific interactions with chiral adsorbates. ACKNOWLEDGMENT The authors thank Dr. M. Blanco Rey, Prof. R. Raval and Drs. A. Mark, M. Forster and S. J. Jenkins for valuable discussions. The EPSRC is acknowledged for financial support, L. Morales de la Garza acknowledged finantial support from DGAPA-UNAM. REFERENCE [1] Topics in Catalysis (2011) 54:1429–1444 44 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ ALD-271 ] Electrical characterization of ALD Al2O3/ZnO nanolaminates Jesús Martínez ([email protected]) 1 , Javier Lopez 1 , Roberto Machorro 1 , David Domínguez 1 , Eduardo Murillo 1 , Mario Curiel 2 , Nikola Radnev 2 , Mario Farías 1 , Hugo Tiznado 1 1 Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México, Apdo. Postal 14, C.P. 22800, Ensenada, México 2 Instituto de Ingeniería, Universidad Autónoma de Baja California, Blvd. Benito Juárez y calle de la Normal s/n Col. Insurgentes Este. CP. 21280 Mexicali, Baja California. México Abstract: Atomic layer deposition (ALD) is an ideal technique in order to growth composite thin films. The thickness and stoichiometry of thin films prepared using ALD is dependent on the underlying surface chemistry during ALD film growth. Composite thin films fabricated by co-depositing two or more different materials via ALD technics can be combined to form alternating layers in order to obtain multilayered laminates. Alternatively, the composite materials may be homogeneously mixed to form alloys. A wide range of physical properties can be achieved by varying the relative proportions of the components; this strategy has been used previously to control numerous thin film properties including refractive index, dielectric constant, lattice parameter, hardness, charge storage capacity, and surface roughness. We used zinc oxide for this research work how to main material, due to it is a known material and used in electronic applications, which it is characterized by its low cost and wide availability. Zinc oxide has new applications as semiconductor, luminescent, and photoconductive materials respectively, while, the aluminum oxide (Al2O3) is one of the most widely used materials in the family of ceramics. It is known as a material with good chemical stability, extremely high hardness and relatively high thermal conductivity. Al2O3 thin films are used as dielectric gate in electronic devices, because it has a high - K dielectric value, being a material with interesting physical properties useful in areas such as micro and optoelectronics. Deposited films were electrically characterized through measurements of the capacitance as a voltage function. Also we made studies of current vs. voltage in order to obtain the electrical properties of the material. Finally, the dielectric constant, equivalent oxide thickness (EOT) and charge density were calculated by these measurements. Keywords: High-K oxide, ALD, electrical properties, thin films. Acknowledgments 45 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla This work was supported by research project PAPIIT - IN105114, PAPIIT - IN107715 and CONACyT - 238402. The authors would like to thank Alex Tiznado, Enrique Medina, Margot Sainz, Juan Peralta and Pedro Casillas, References 1. Kattelus, H.; Ylilammi, M.; Saarilahti, J.; Antson, J.; Lindfors, S. Thin Solid Films 1993, 225, 296 2. Stromme, M.; Niklasson, G. A.; Ritala, M.; Leskela, M.; Kukli, K. J. Appl. Phys. 2001, 90, 4532. 3. Fujiwara, H.; Nabeta, T.; Shimizu, I. Jpn. J. Appl. Phys. 1994, 33, 2474. 4. Chu, X.; Wong, M. S.; Sproul, W. D.; Barnett, S. A. J. Mater. Res. 1999, 14, 2500. 5. Kukli, K.; Ritala, M.; Leskela, M. J. Appl. Phys. 1999, 86, 5656. 6. Elam, J. W.; Sechrist, Z. A.; George, S. M. Thin Solid Films 2002, 414, 43. 7. Khalid Omar, M. D. Johan Ooi & M. M. Hassin, Modern Applied Science, 2009, Vol.3, No. 2. 8. Puurunen R. L. J. Appl. Phys, 2005, Vol. 97, pp. 121301. 9. Jiang Ran, Meng Lingguo, Zhang Xijian, Hyung-Suk Jung, and Cheol Seong Hwang. Journal of Semiconductors, 2012, Vol. 33 (9), 093004. [ ALD-274 ] Electrical characterization of ALD Al2O3/Y2O3 nanolaminates Jesús Martínez ([email protected]) 1 , Javier Lopez 1 , Roberto Machorro 1 , David Domínguez 1 , Eduardo Murillo 1 , Mario Curiel 2 , Nikola Radnev 2 , Mario Farías 1 , Hugo Tiznado ([email protected]) 1 1 Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México, Apdo. Postal 14, C.P. 22800, Ensenada, México 2 Instituto de Ingeniería, Universidad Autónoma de Baja California, Blvd. Benito Juárez y calle de la Normal s/n Col. Insurgentes Este. CP. 21280 Mexicali, Baja California. México Abstract: Dielectric materials based on metallic oxides as ZrO2, Al2O3, Y2O3, TiO2, are very interesting properties and exhibiting high - K dielectric constants which improve the electrical properties in the different devices for microelectronic and optoelectronic applications in nanotechnology specially for microchip-embedded that provides energy storage in high-capacitance capacitors. Aluminum oxide (Al2O3) is one of the most widely used materials in the family of ceramics. It is known as a material with good chemical stability, extremely high hardness and relatively high thermal conductivity. Al2O3 thin films 46 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla are used as dielectric gate in electronic devices, because it has a high - K dielectric value, being a material with interesting physical properties useful in areas such as micro and optoelectronics. Yttrium oxide (Y2O3) is a material with several interesting diverse applications due to its thermal stability with a high melting point (2439°C), optical transparency from 300 nm to ~11 µm range, high refractive index, and useful electrical properties. In optical applications, its high refractive index can be used in the manufacturing of optical waveguides and multilayer dielectric coatings that might enhance the optical surfaces for optoelectronic applications in order to modify the transmittance and reflectance properties of the materials to which are applied. Atomic layer deposition (ALD) is an ideal technique for fabricate composite thin films. The thickness and stoichiometry of composite thin films prepared using ALD is dependent on the underlying surface chemistry during ALD film growth. Composite thin films may be fabricated by co-depositing two or more materials that may be combined in alternating, discrete layers to form multilayered laminates. These composite materials can be homogeneously mixed to form alloys. A wide range of physical properties may be achieved by varying the relative proportions of the components. This strategy has been used previously to control numerous thin film properties including refractive index, dielectric constant, lattice constant, hardness, charge storage capacity, and surface roughness. Deposited films were electrically characterized through measurements of the capacitance as a voltage function. Also we made studies of current vs. voltage in order to obtain the electrical properties of the material. Finally, the dielectric constant, equivalent oxide thickness (EOT) and charge density were calculated by these measurements. Keywords: High-K oxide, ALD, electrical properties, thin films Acknowledgments This work was supported by research project PAPIIT - IN105114, PAPIIT - IN107715 and CONACyT 238402. The authors would like to thank Alex Tiznado, Enrique Medina, Margot Sainz, Juan Peralta and Pedro Casillas. References 1. Jiang Ran, Meng Lingguo, Zhang Xijian, Hyung-Suk Jung, and Cheol Seong Hwang. Journal of Semiconductors, 2012, Vol. 33 (9), 093004. 2. Prodyut Majumder, Gregory Jursich, Adam Kueltzo and Christos Takoudis, Journal of The Electrochemical Society, 155 (8) G152-G158 (2008) 3. Kattelus, H.; Ylilammi, M.; Saarilahti, J.; Antson, J.; Lindfors, S. Thin Solid Films 1993, 225, 296 4. Stromme, M.; Niklasson, G. A.; Ritala, M.; Leskela, M.; Kukli, K. J. Appl. Phys. 2001, 90, 4532. 5. Fujiwara, H.; Nabeta, T.; Shimizu, I. Jpn. J. Appl. Phys. 1994, 33, 2474. 6. Chu, X.; Wong, M. S.; Sproul, W. D.; Barnett, S. A. J. Mater. Res. 1999, 14, 2500. 7. Kukli, K.; Ritala, M.; Leskela, M. J. Appl. Phys. 1999, 86, 5656. 8. Elam, J. W.; Sechrist, Z. A.; George, S. M. Thin Solid Films 2002, 414, 43. 47 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ ALD-351 ] Soft nitridation of ALD-hafnium oxide by remote plasma Zeuz Montiel González ([email protected]) 1 , Yuri Lizbeth Chipatecua Godoy 1 , Jorge Alejandro Torres Ochoa 1 , Oscar Ceballos Sánchez 1 , Gustavo Gómez Sosa 1 , Andrés de Luna Bugallo 1 , Alberto Herrera Gómez 1 1 Cinvestav-Queretaro, Libramiento Norponiente 2000, Real de Juriquilla, Queretaro 76230, México Currently, there is an intensive search for high-k materials that can replace SiO2 as gate dielectric in metal-oxide-semiconductor (MOS) devices. In this context, several deposition methods and/or chemical treatments have been employed to improve their chemical and electrical properties. The incorporation of nitrogen into the dielectric does not only improves the value of the dielectric constant but it also reduces the leakage current, prevents interfacial reactions and increases the crystallization temperature. Several approaches to the nitridation of the dielectric have been studied, for instance the thermal exposure to N sources, direct contact with N plasma, and treatment with a N remote plasma source (RPS). In this work, a study of the remote plasma nitridation of HfO2 grown with atomic layer deposition (ALD) is presented. The nitridation was carried out under a pressure of 0.1 Torr and with a flow rate of 100 sccm of ultra-high purity N2 for 10 minutes. The degree of nitridation and the nitrogen incorporation mechanism were evaluated as a function of the RPS power (0.5, 1.0 and 1.5 kW) and the dielectric temperature (300, 400 and 500 °C). The analysis of the structure of the HfOxNy films was done with angle resolved X-ray photoelectron spectroscopy. The results showed a strong dependence on the plasma power and dielectric temperature, and the presence of different nitrogen species distributed along the HfO2 layer. 48 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ ALD-373 ] Application of ALD for the Research & Development of Advanced Logic, Memory and Sensing Technologies. Joel Molina ([email protected]) 1 , Berni Manolo Perez Ramos 1 , Hector Uribe 1 , Rene Valderrama 1 , Omar Lopez 1 , Oscar Pestaña 1 1 Instituto Nacional de Astrofisica, Óptica y Electrónica (INAOE), Grupo de Microelectrónica. We review the application of Atomic-Layer Deposition for development of advanced logic, memory and sensing technologies being developed at INAOE. The focus is on the deposition, processing and performance characterization of advanced MOSFET, FinFET, ReRAM, ISFET and ISCAP devices along with the fundamental problems associated to the deposition of ALD-dielectrics for these technologies. [ ALD-400 ] Growth and Characterization of TiO2 Films Grown by Atomic Layer Deposition for photocatalytic applications María Magdalena Montsserrat Contreras Turrubiartes ([email protected]) 1 , Aura Pedrosa Rodríguez 2 , Juan Carlos Salcedo Reyes 2 , Pierre Giovanni Mani González 3 , Edgar López Luna 1 1 Coordinación para la Innovación y Aplicación de la Ciencia y la Tecnología, Universidad Autónoma de San Luis Potosí, Av. Sierra Leona #550, Col. Lomas 2a. Sección 2 Pontificia Universidad Javeriana de Bogotá, Carrera 7 # 40-62, Bogotá, Colombia 3 Universidad Autónoma de Ciudad Juárez, Av. Plutarco Elías Calles 1210, Col. Fovissste Chamizal, 32310 Ciudad Juárez, CHIH Due to the current global needs of efficient processes for purification of waste waters has recently been a significant increase in research, in particular, heterogeneous photocatalysis by titanium dioxide , due mainly to its ability to induce chemical reactions of oxidation and reduction of the oxygen molecules adsorbed on the semiconductor/medium interface , producing the proven effect biocide and sterilizing of TiO2 . Although studies have been conducted with other semiconductor photocatalysis mainly CdS and CdSe , it has been 49 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla observed that with TiO2 the higher is obtained. In addition, the TiO2 material is inexpensive, non-toxic and chemically inert biological. The study of the photocatalytic properties of TiO2 were performed with films formed from a suspension of titanium powder (in anatase phase) TiO2 thin films can be grow by other methods as: Sol- gel, sputtering, spray-pyrolysis and Atomic Layer Deposition. In this paper we present the results for establish the parameters for the growth of thin films of titanium dioxide (TiO2) in anatase phase by Atomic Layer Deposition (ALD), their optical characterization through photoluminescence (PL) , and surface characteristics by atomic force microscopy (AFM) . It also proposes a study of the efficiency of photocatalytic TiO2 films grown by ALD, depending on the film thickness, by means of the time-dependent decrease in the degradation of color units using as one model contaminant solution of methylene-blue, for potential applications in sewage purification. Also shows the results for inactivation test for E.Coli bacteries. [ ALD-412 ] Determination of the surface saturation, aperture-times and number of cycles of HfO2 and TiO2 on Si (100) by ALD Pierre Giovanni Mani González ([email protected]) 2 , María Magdalena Montsserat Contreras Turrubiartes 1 , Edgar Lopez Luna 1 , Hugo Leos Méndez 2 , Heber Hernández Arriaga 1 , Jesús Alfredo Hernández Márquez 2 , José Rurik Farías Mancilla 2 , José Trinidad Elizalde Galindo 2 , Miguel Ángel Vidal Borbolla 1 1 Coordinación para la Innovación y Aplicación de la Ciencia y la tecnología (CIACyT), Universidad Autónoma de San Luis Potosí 2 Instituto de Ingeniería y Tecnología, Departamento de Física y Matemáticas, Universidad Autónoma de Ciudad Juárez A systematic analysis was performed to determine the characteristic times of surface coverage of oxidant-agent on silicon substrates (100) by the method of atomic layer deposition (ALD) in order to ensure the saturation of the surface substrate for growth. The aperture-times of the precursors have been studied due to stoichiometric impact of the layers and also at the interface. The numbers of cycles were critical for the interface formation at the early stage growth. This work emphasizes in the study and analysis of the growth surface evolution (amount of free bonds) with respect to the aperture-times of hafnium or titanium precursor remains open (saturation time) and with amount of cycles as function of layers and 50 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla interfaces (stoichiometry). Previous works complement with results obtained in study the growth of hafnium oxide and titanium oxide by atomic layer deposition (ALD) demonstrating the close relationship between the thickness and composition of the interface layer with the number of cycles performed by the ALD and with the aperture-time of the precursors. This analysis shows a base that will allow create hafnium oxide and titanium oxide nanofilms with optimal characteristics. [ ALD-422 ] ALD for the Development of Integrated Chemical Sensors Berni Manolo Pérez Ramos ([email protected]) 1 , Joel Molina Reyes 1 1 Departamento de Electrónica, Instituto Nacional de Astrofísica, Óptica y Electrónica, Luis Enrique Erro 1, Tonantzintla, Puebla, México, 72000 The development driven by miniaturization in the electronics industry has raised the need for technologies that enable film deposition thickness control at the atomic level. Also, the requirements for the manufacture of structures with large aspect ratios make it necessary to have deposition systems for production of very uniform and conformal films. This is why atomic layer deposition (ALD) of films has become an essential tool for processing a wide variety of materials in a wide range of different electronic applications. One area that has taken advantage of ALD technology development is the manufacture of solid state chemical sensors. This type of sensors employs dielectrics (usually metal oxides) to operate as ionsensitive gate materials. The presence of amphoteric sites on the surface of these dielectrics makes the surface electrically charged due to adsorption of determining ions, and this in turn causes a potential difference in the electrolyte-insulator-semiconductor system (EIS) which can be detected, for example, as a change in the threshold voltage of a MOS transistor. All these inorganic materials such as Si3N4, Al2O3, ZrO2, Ta2O5 and HfO2, can be processed by ALD and are regularly employed in a wide variety of chemical sensors. Specifically, the application of dielectrics deposited by ALD in solid state chemical sensors provides significant advantages: manufacture of low-defect films, precise control of thickness at the atomic scale, and conformal deposition on structures with a large aspect ratio. Also, the self-limited sequential chemical reactions of the ALD process lead to highly stoichiometric films that favor the generation of high densities of reactive sites on the dielectrics surface, and improve the electrochemical sensor response. This is why we use ALD dielectric films as sensitive areas in capacitive ion sensors (ISCAP) and extended gate ISFET (EG-ISFET) sensors. Thin Al2O3 films (10nm) are deposited onto the gate sensitive areas using TMA and water as precursor gases at a temperature of 250 °C. The chemical characteristics of the films are determined by FTIR measurements, and a correlation has been 51 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla found between changes in the density of specific chemical bonds with temporal variations in the sensitivity of these sensors. These devices have averages sensitivities of 54 [mVpH-1] and 0.8 [pFpH-1], for EG-ISFETs and ISCAPS, respectively. In conclusion, the application of films deposited by ALD, with all the advantages that this technology provides, allows us to manufacture various kinds of chemical sensors with good sensitivity and stability characteristics when compared to other reports. [ ALD-423 ] ALD for development of Advanced Logical Technology Héctor Manuel Uribe Vargas ([email protected]) 1 , Joel Molina Reyes 1 1 INAOE As the dimension of advanced electronic devices reach nanometric scales, high-k materials (La2O3, Al2O3, HfO2) are used as gate oxides to achieve an EOT <1nm in state-of-the-art Complementary Metal-Oxide-Semiconductor (CMOS) devices. These oxides need to have some specific characteristics, such as low-deposit temperature (<300°C), a very accurate film thickness (due to a small variation in the physical thickness could modify greatly the electrical characteristics); a precise stoichiometry and a conformal deposition in 3 dimensions, which is the base for the new SOI technology (Partially Depleted and Fully Depleted). ALD technique fully complies with these characteristics, and that’s why is an important piece in the continuous scaling of advanced electronic devices. For the particular case of MetalOxide-Semiconductor Field-Effect Transistor (MOSFET) devices having nanometer features, an exponential increase in its gate leakage current translates into continuous waste of energy (in the form of overheating) which in turn, increases power consumption, also present DIBL, which translates in a Vth shift and this is not desirable. The heart of the MOSFET technology is the MOS capacitor and in this work, MOS capacitors were fabricated using high-k gate oxides deposited with the Savannah-S100 of Cambridge Nanotech ALD system. The gate oxides were HfO2 (4nm) and Al2O3 (10nm) which requires the TDMAH and TMA precursors. Then, 40nm of aluminum were deposited as gate electrode in ultra-high vacuum conditions using the Temescal BJD-1800 from Edwards E-beam evaporation system. Capacitors were electrically characterized in order to experimentally measure their conduction properties regarding the gate leakage current. Experimental measurements of the 52 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla gate leakage current were compared with semi-empiric conduction models and with simulations using Minimos NT. Also 28nm MOSFET transistors (planar technology) were electrically characterized in order to measure the gate leakage current and compare it with the devices fabricated at INAOE. [ ALD-435 ] ALD for the Development of Emergent NonVolatile Memory Devices Rene Valderrama ([email protected]) 1 , Joel Molina 1 1 Electronics Department, National Institute of Astrophysics, Optics and electronics (INAOE), Tonantzintla, Puebla, 72000, Mexico. FLASH memories had been in a technologic niche for a long time, but difficulties in their scaling have led the research into resistive switching memories (ReRAM), which have a simple structure (Metal-Insulator-Metal) therefore, they can be greatly scaled and integrated into a three-dimensional arrangement. Due to the control at atomic level of the thickness and the magnificent uniformity of the film, ALD (Atomic Layer Deposition) has emerged as a crucial technique for the development of ReRAM memories. Here, the typical resistive switching materials (RS) used are TiO2, NiO, ZrO2, HfO2, ZnO, Al2O3 [1]. They are the kinds of materials that can be deposited easily by ALD. For the development of ReRAM memory devices in INAOE, we have chosen HfO2 and Al2O3 as RS materials, because both are present in commercial semiconductor devices, in addition, we take advantage of the low temperature (<300°C) in the deposit process in order to study the possible integration of these memories into the BEOL stage (Back-End of Line) of integrated circuits (ICs), which would increase (at least one order of magnitude) the integration density. For the fabrication of these memory devices (MIM structures), we have used Corning Glass and N-type Silicon wafers as substrates. Tungsten and aluminum were deposited by E-beam Evaporation under ultra-high vacuum conditions and they were used as metal electrodes. ALD system (Savannah-S100 from Cambridge Nanotech) is used to deposit ultra-thin layers of HfO2 and Al2O3, where TDMAH and TMA along with H2O are the precursors for each condition respectively. Photolithography and thermal treatments under different atmospheres are performed in order to obtain final structures. From electrical characterization, resistive switching having a large IOFF/ION relation as well as both unipolar and bipolar operation mode are shown in our devices. Whit the latter we can conclude that, the ALD system allows us to development emergent memory devices, which can be vertically integrated into the unexploited process stages of the integrated circuits such as BEOL processing. [1] R. Waser, R. Dittmann, G. Staikov, and K. Szot, Adv. Mater. 21, 2632 (2009). 53 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ ALD-443 ] IGZO transistors using HfO2 and Al2O3 as dielectric layer by ALD Eduardo Martinez-Guerra ([email protected]) 1 , Octavio Luebbert-Larios 1 , Rodolfo Rodríguez Dávila 2 , Francisco Servando Aguirre-Tostado 1 , Manuel A. Quevedo 2 1 Centro de Investigación en Materiales Avanzados, S.C.(CIMAV), Av. Alianza Norte #202, Parque de Investigación e Innovación Tecnológica (PIIT), Nueva Carretera Aeropuerto Km. 10, Apodaca, Nuevo León, México. C. P. 66600. 2 Department of Materials Science and Engineering, University of Texas at Dallas, Richardson, Texas, 75080 Amorphous oxide semiconductors (AOS) have been widely investigated for flexible electronics applications, such as flexible Thin Film Transistors (TFTs), due to their larger field effect mobility in comparison with amorphous silicon TFTs, and also to the fact that they can be obtained at room temperature [1]. Amorphous indium gallium zinc oxide (IGZO) has several advantages among AOS, such as mobilities over 10 cm2/Vs and the possibility to control carrier concentration with the variation of cations through the semiconductor [2]. We investigate the effect of oxygen Pressure on the electrical, optical and structural properties of amorphous InGaZnO (a-IGZO) deposited by Puled Laser Deposition and RF Ion Sputtering at room temperature. Films were prepared onto highly doped p-type silicon <100>, glass and PET as substrates. The electrical resistivity and the carrier density showed large variation with changes in the oxygen pressure. It was found a minimum resistivity for those films deposited at 10 mTorr and a huge increment in those films deposited at 80 mTorr. It was found by XRD that all films deposited at room temperature exhibit an amorphous structure. On the other hand, the physical properties of the films like transparency, electron mobility, and free-electron concentration were found to be correlated to the oxygen pressure during the deposition and in turn to the possible oxygen vacancies or metallic interstitial in the film. The energy gap estimated from the optical transmittance showed an increasing tendency with increasing oxygen pressure. When carrier concentration was less than 1019 cm3 , the temperature dependence of hall mobility showed thermally-activated behavior while carrier concentration was independent of temperature, showed almost degenerated conduction at Ne>1018 cm-3. Films with better performance were used as active channel in TFT fabricated by shadow mask and photolithography. For films deposited at low pressure, less than 20 mTorr, transistors showed low ION/IOff ratio with high saturation current (ISat) which suggest low resistivity. For those films deposited at pressures higher than 30mTorr, the ION/ IOff increase 54 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla up to 107 with ISat in range 10-3 to 10-5. Field Effect mobility is higher than 10 cm2/(V*s) for those films with oxygen treatment. Our results suggest that oxygen pressure can be exploited as key parameter to control the electrical and the optical properties of a-IGZO films deposited by PLD and RF Ion Sputtering. Collagen is a biocompatible and biodegradable protein abundant in mammals. This work also demonstrates the opportunity of using an Al2O3 dielectric layer on collagen substrate for new biosensor applications. The authors gratefully acknowledge to The University of Texas at Dallas (UTD) through the Flexible Electronics Research group headed by Dr. Manuel Quevedo for fruitful discussions and technical facilities. The authors also thanks to N.Pineda, C. Leyva-Porras, L.G.Silva, E. Longoria R. for their technical support. [1] Kamiya, T., Nomura, K., & Hosono, H., Present status of amorphous In-Ga-Zn-O thinfilm transistors. Science and Technology of Advanced Materials, 2010. 11(4): p. 044305. [2] Nomura, K., et. al., Room-temperature fabrication of transparent flexible thin-film transistors using amorphous oxidesemiconductors. Nature, 2004. 432: p. 488-492. [ ALD-489 ] Processing and Performance Simulation of Advanced MOSFET and FinFET Devices based on Metal Gate/High-k Materials Omar López ([email protected]) 1 , Joel Molina ([email protected]) 1 1 Instituto Nacional de Astrofísica, Óptica y Electrónica (INAOE), Grupo de Microelectrónica. Tonanzintla, Puebla, 72840, México. Processing and Performance Simulation of Advanced MOSFET and FinFET Devices based on Metal Gate/High-k Materials A simulation (CAD) analysis of advanced MOSFET devices is presented in this work, where high k dielectric materials have been used as ultra-thin gate dielectrics. For these, the deposition process of metallic oxides by atomic layer (ALD) instead of chemical vapor deposition (CVD) represents a key step for device fabrication, this is, working with lower processing temperatures compared to CVD method, as well as having an ideal conformal deposition process in order to fully cover complex three-dimensional structures (with highaspect ratio) of an integrated circuit. The ALD method is quite compatible with the CMOS 55 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla advanced fabrication processing in order to deposit and/or process these materials while maintaining their thermodynamic stability conditions (considering that after deposition of these metallic oxides, the final devices are subjected to relatively high thermal treatments). Some of these ALD materials are: Al2O3, ZrO2 and HfO2, and they are used in advanced transistors like FD SOI-MOSFETs, FinFETs, etc. Using different structures for these oxides the intention is to improve the carrier mobility in the advanced transistors channel and using materials like Ge (for PFET channel) or III-V materials like InGaAs (for NFET channel). On the other hand, use of high K dielectrics in MOSFETs has resulted in a reduction of the equivalent oxide thickness (EOT), thus giving a better control of the OFF-ON states of transistors. In state-of-the-art MOSFET devices, the EOT obtained is 20 Å (2nm). In this work our simulations are developed in the Athena module for the design and virtual fabrication of all deices; the Atlas module is also used for its characterization performance, both belonging to SILVACO. Atlas allows us setting the metal’s effective work function when used with these high k gate insulators; this is a charge neutrality level model, where pre-set work function values can be used as well. From this work, it has been possible to determine the main design parameters for advanced MOSFET devices, which are so important in order to migrate from a planar MOSFET to a three-dimensional FinFET device. 56 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla Poster Session [ ALD-206 ] Thickness Effect on the Optical, Morphological and Physicochemical Properties in Al2O3/ZnO Nanolaminate Thin Films Prepared by Atomic Layer Deposition Javier López Medina ([email protected]) 1 , Jesús Martínez 1 , Noemí Abundiz 1 , David Domínguez 1 , Felipe Castillón 1 , Roberto Machorro 1 , Mario H. Farías 1 , Hugo Tiznado 1 1 Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México In this work, we studied the optical, morphological and physicochemical properties in ultrathin nanolaminate films based on bilayers of Al2O3/ZnO (AZ) deposited on Si (100) by thermal atomic layer deposition (ALD) technique, changing the thickness between bilayers (0.1, 0.5, 1, 2, 5 and 10 nm). Through this technique it is possible to obtain control of the thickness of layers during the growth, making this a self-limiting and self-controlling process to coating surfaces, which allows high aspect ratio. Optical properties such as refractive index (n), extinction coefficient (k), broad bandgap (Eg) and dielectric function (e) of each nanolaminate, were studied via spectroscopic ellipsometry, and spectral reflectance UV – vis. The optical and electronic properties of nanolaminates are strongly determined by its dielectric constant and therefore it is an important parameter to consider in order to improve performance of electronic devices such as high - K dielectric constant capacitors. In order to obtain information about the surface morphology and roughness parameters for the nanolaminates, Atomic Force Microscopy (AFM) was used. Finally, we studied by X-Ray Photoelectron Spectroscopy (XPS) to determine the chemical composition of the surface of each of the samples. These kind of systems are considered materials with interesting technological applications in nanotechnology, because it is expected that the combination of different dielectric materials in the form of mixed oxides or nanolaminates, exhibit optical properties that enhance its dielectric response. This behavior has great interest in nanoelectronics and optoelectronics. Keywords: Nanolaminates films, Atomic Layer deposition, Dielectric Constant, high- K oxide films, Optical properties. Acknowledgements This work was supported by research project PAPIIT - IN105114 and IN107715. J. López thanks DGAPA for the postdoctoral fellowship position. 57 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ ALD-253 ] Design, assembly and control of an atomic layer deposition system (ALD) Hugo Leos Méndez ([email protected]) 1 , Pierre Giovanni Mani González ([email protected]) 1 , Mario Eduardo Ruelas Corral 1 , Juan Francisco Hernández Paz 1 , Jose Trinidad Elizalde Galindo 1 , Jose Rurik Farias Mancilla 1 1 Departamento de Física y Matemáticas, Instituto de Ingeniería y Tecnología, Universidad Autónoma de Ciudad Juárez, Ave. Del Charro 450, Cd. Juárez. C.P. 32310, Chihuahua, México. The atomic layer deposition (ALD) is a technique of layer-by-layer growth at nano-metric level in a controlled and highly accurate form. The purpose of this work is to describe the basic features of the ALD system that is being built. The specific design of key parts of the system allows to obtain certain fundamental properties during the cycle. The reactor is the element that holds the growth process, also is the main stronghold of the structure. Made of stainless steel, it features a design that allows optimize tasks that facilitate the accumulation of cycles in the process. This has an input duct for the precursors and another for the output. The growth zone of the films is at the center with a gap depth to prevent movement of the product during the process. Just below the growth zone is found a hole which will hold a flat circular resistance responsible to provide the required heat to the system. An important feature to consider is the system protection against leakage during the cycle. This ALD system has an O-ring in the reactor that provides a pressure seal that isolates the system of large leaks. The skeletal of the system consists of pipe and stainless steel connectors with standardized measures. To provide the low vacuum and purge required to the reactor during the process is used a vacuum pump of medium power capable of providing a maximum vacuum of 1 x 10 -4 tor. The use of electro-pneumatic valves 2/2 to control the flow of precursors during the cycle. To control the system is used an embedded system Arduino UNO. With a low cost and flexibility this controller uses a high-level language for creating routines and subroutines with a specific purpose in the process. Capable of handling digital inputs and outputs, also has a section aimed to analog inputs which allows to introduce important variables for optimal control of the system such as temperature, pressure, flow, etc. The ability to communicate with a platform of design and graphic control, such as Labview, allows us to optimize and extend the control/monitoring of the ALD system. 58 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ ALD-270 ] Electrical characterization of Al2O3/ZrO2 nanolaminates Jesús Martínez ([email protected]) 1 , Javier Lopez 1 , Roberto Machorro 1 , David Domínguez 1 , Eduardo Murillo 1 , Mario Curiel 2 , Nikola Radnev 2 , Mario Farías 1 , Hugo Tiznado 1 1 Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México, Apdo. Postal 14, C.P. 22800, Ensenada, México 2 Instituto de Ingeniería, Universidad Autónoma de Baja California, Blvd. Benito Juárez y calle de la Normal s/n Col. Insurgentes Este. CP. 21280 Mexicali, Baja California. México Abstract: With the density increase and the minimum feature size of dynamic random access memory (DRAM), high-k dielectric materials in metal–insulator–metal (MIM) capacitor have been investigated to obtain sufficient capacitance for refresh requirements. MetalInsulator-Metal capacitors, with ZrO2/Al2O3/ZrO2 (ZAZ) - nanolaminate thin-films as a dielectric layer, exhibit reduced leakage currents compared to capacitors based on pure ZrO2 respectively. These systems providing a high dielectric constant suitable for DRAM applications. ZAZ dielectric laminate grown by atomic layer deposition (ALD) has a mixture of both crystalline and amorphous phases caused by the presence of ZrO2 and Al2O3 oxides in order to coordinate the balance between capacitance and leakage current in the capacitor performance. Although the crystallization of ZrO2 may induce the presence the leakage current in the thin films, the dielectric constant of ZrO2 can be significantly enhanced, when ZrO2 film it is remains in tetragonal phase (k=47), but the combination with another dielectric that has higher bandgap as amorphous Al2O3 could avoid the leakage current in the material. in addition, Al2O3 layer will produce capacitance loss due to its relatively lower dielectric constant (∼9). In this work, we studied the electrical properties in ultrathin nanolaminate films based on bilayers of Al2O3/ZrO2 deposited on Si (100) by thermal atomic layer deposition (ALD) technique, changing the thickness between bilayers (0.1, 0.5, 1, 2, 5 y 10 nm). Deposited films were electrically characterized through measurements of the capacitance as a voltage function. Also we made studies of current vs. voltage in order to obtain the electrical properties of the material. Finally, the dielectric constant, equivalent oxide thickness (EOT) and charge density were calculated by these measurements. Keywords: High-K oxide, ALD, electrical properties, thin films. Acknowledgments 59 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla This work was supported by research project PAPIIT - IN105114, PAPIIT - IN107715 and CONACyT - 238402. The authors would like to thank Alex Tiznado, Enrique Medina, Margot Sainz, Juan Peralta and Pedro Casillas. References 1. Ming-Yen Li, Bin-Siang Tsai, Pei-Chuen Jiang, Hsiao-Che Wu, Yung-Hsien Wu, Yu-Jen Lin, Thin Solid Films 518 (2010) 5272–5277 2. Dominik Martin, Matthias Grube, Wenke Weinreich, Johannes Müller, Walter M.Weber, Uwe Schröder, Henning Riechert, and Thomas Mikolajick, JOURNAL OF APPLIED PHYSICS 113, 194103 (2013) 3. D. Vanderbilt, X. Zhao, D. Ceresoli, Thin Solid Films 486 (2005) 125. 4. D.S. Kil, H.S. Song, K.J. Lee, K. Hong, J.H. Kim, K.S. Park, S.J. Yeom, J.S. Roh, N.J. Kwak, H.C. Sohn, J.W. Kim, S.W. Park, Development of New TiN/ZrO2/Al2O3/ZrO2/TiN Capacitors Extendable to 45nm Generation DRAMs Replacing HfO2 Based Dielectrics, Honolulu, U.S.A., June 13–15, 2006, Symposium on VLSI Technology, Digest of Technical Papers, , 2006, p. 38. [ ALD-275 ] Electrical characterization of Y2O3/ZrO2 nanolaminates Jesús Martínez ([email protected]) 1 , Javier Lopez 1 , Roberto Machorro 1 , David Domínguez 1 , Eduardo Murillo 1 , Mario Curiel 2 , Nikola Radnev 2 , Mario Farías ([email protected]) 1 , Hugo Tiznado 1 1 Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México, Apdo. Postal 14, C.P. 22800, Ensenada, México 2 Instituto de Ingeniería, Universidad Autónoma de Baja California, Blvd. Benito Juárez y calle de la Normal s/n Col. Insurgentes Este. CP. 21280 Mexicali, Baja California. México Abstract: Silicon dioxide (SiO2) has been used as the primary gate dielectric material in field-effect devices since the advent of the first integrated circuit. However, this kind of material has limitations when applied as gate dielectrics due to the exponential increase in tunneling current with decreasing its thickness. Currently, different investigations carried to improve the limitations caused for the silicon oxide thickness, have suggested the use of several materials that can replace the SiO2. For example, gate dielectrics, such as Ta2O5, TiO2, Y2O3, and ZrO2 can be used. Unfortunately, most of these materials are not thermally stable on silicon. However, often occurs the possible formation of SiO2 or metal silicides when these materials are deposited on silicon or during subsequent annealing. It is known 60 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla that SiO2 has a lower dielectric constant; therefore an underlying SiO2 layer can reduce the effective capacitance of the film. Yittria-stabilized zirconia oxide (YSZ, with dielectric constant 25–29.7), It is a material with interesting dielectric properties that can be used as alternative gate dielectrics due to it is considered as one of the few materials that can be thermodynamically stable in contact with silicon at 1000 K. In this work, we studied the electrical properties in ultrathin nanolaminate films based on bilayers of Y2O3/ZrO2 deposited on Si (100) by thermal atomic layer deposition (ALD) technique, changing the thickness between bilayers (0.1, 0.5, 1, 2, 5 y 10 nm). Deposited films were electrically characterized through measurements of the capacitance as a voltage function. Also we made studies of current vs. voltage in order to obtain the electrical properties of the material. Finally, the dielectric constant, equivalent oxide thickness (EOT) and charge density were calculated by these measurements. Keywords: High-K oxide, ALD, electrical properties, thin films. Acknowledgments This work was supported by research project PAPIIT - IN105114, PAPIIT - IN107715 and CONACyT 238402. The authors would like to thank Alex Tiznado, Enrique Medina, Margot Sainz, Juan Peralta and Pedro Casillas. References 1. Roy P K and Kizilyalli I C 1998 Appl. Phys. Lett. 72 2835. 2. Campbell S A, Kim H S, Gilmer D C, He B,Ma T and GladfelterWL 1999 IBM J. Res. Dev. 43 383. 3. Choi S C, Cho M H, Whangho SW, Whang C N, Kang S B, Lee S I and LeeMY 1997 Appl. Phys. Lett. 71 903. 4. Copel M, Gribelyyuk Mand Gusev E 2000 Appl. Phys. Lett. 76 436. 5. SJ Wang, Semicond. Sci. Technol. 16 (2001) L13–L16. 61 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ ALD-276 ] Study of the optical, electrical and physicochemical properties in dielectric nanolaminate thin films based on Al2O3/ ZrO2 prepared by Atomic Layer Deposition Javier A. López Medina ([email protected]) 1 , Jesús Martínez 1 , Noemí Abundiz 1 , David Domínguez 1 , Felipe Castillón 1 , Roberto Machorro 1 , Mario H. Farías 1 , Hugo Tiznado ([email protected]) 1 1 Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México Nanolaminates of different mixed oxides bilayers, exhibit high-K dielectrics constants that makes them interesting materials for applications in microelectronics and optoelectronics. In this work, we studied the optical, electrical, morphological and physicochemical properties in ultrathin nanolaminate films based on bilayers of Al2O3 – ZrO2 (AZ) deposited on Si (100) by thermal atomic layer deposition (ALD) technique, changing the thickness between layers 0.1 to 10 nm). Through this technique it is possible to obtain the thickness control of the atomic layers during the growth, making this a self-limiting and self-controlling process to coating surfaces which allows high aspect ratio. Optical properties such as refractive index (n), the extinction coefficient (k), bandgap (Eg) and the dielectric function (e) of each nanolaminates, were studied via spectroscopic ellipsometry, and spectral reflectance UV – vis. The optical and electronic properties of nanolaminates are strongly determined by its dielectric constant and therefore it is an important parameter to consider in order to improve performance of electronic devices such as high - K dielectric constant capacitors. In order to obtain information about the surface morphology and roughness parameters for the nanolaminates, Atomic Force Microscopy (AFM) was used. Finally, we studied by X-Ray Photoelectron Spectroscopy (XPS) to determine the chemical composition of the surface of each of the samples. These kinds of systems are considered materials with interesting technological applications in nanotechnology, due it is expected that the combination of different dielectric materials in form to nanolaminates exhibit optical properties that enhance its dielectric response, this behavior have great interest in nanoelectronics. Keywords: Nanolaminates films, Atomic Layer deposition, Dielectric Constant, high- K oxide films, Optical properties. Acknowledgements This work was supported by research project PAPIIT - IN105114 and IN107715. J. López thanks DGAPA for the postdoctoral fellowship position. 62 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ ALD-383 ] STUDY OF THE DIELECTRIC CONSTANT OF HfO2 GROW BY ALD DETERMINED IN Ni/HfO2/c-Si MOS STRUCTURES Jorge Alejandro Torres-Ochoa ([email protected]) 1 , Zeus MontielGonzalez 1 , Yuri Lizbeth Chipatecua-Godoy 1 , Gustavo Gomez-Sosa 1 , Gabriela Molar-Velazquez 1 , David Salvador Garcia-Saleta 1 , Andres De Luna-Bugallo 1 , Alberto Herrera-Gomez 1 1 CINVESTAV-QUERETARO Hafnium oxide (HfO2) is nowadays widely employed in metal-oxide-semiconductor (MOS) devices. Since the independent characterization of the interface layer is difficult, the precise quantitative correlation between the structure of the device and the effective dielectric constant still represent an open problem. In this work we evaluate the behavior of HfO2 films grown on crystalline silicon (c-Si), both hydrogen-terminated and with a thin thermal oxide. Nickel was employed as gate metal. Hafnia films of different thicknesses (2, 4, 8 and 16 nm) were grown at 250 °C by atomic layer deposition (ALD) using tetrakisdimethylamido hafnium and water as precursors. Metallic Ni (200 nm) contacts are deposited using a sublimation system with base pressure of ~5x10-8 Torr and working pressure of ~5x10-3 Torr. Angle resolved X-ray photoelectron spectroscopy (ARXPS) measurements were carried out to determine chemical and structural composition. Finally, MOS electrical properties were measured through C-V characteristics to correlate the electric, structural and chemical properties of the Ni/HfO2/c-Si films. Keyword: Hafnium, MOS device, dielectric constant. [ ALD-401 ] Manufacture of a Growth Chamber for a ALD equipment María Magdalena Montsserrat Contreras Turrubiartes ([email protected]) 1 , José Nieto Navarro 1 , Edgar López Luna 1 1 Coordinación para la Innovación y Aplicación de la Ciencia y la Tecnología, Universidad Autónoma de San Luis Potosí, Av. Sierra Leona #550, Col. Lomas 2a. Sección 63 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla In this work we present the fabrication for an ALD growth chamber. The design, selection of the right materials and the subsequent manufacture of the necessary connections for proper operation. The corresponding images of the process and the results are presented. [ ALD-444 ] Crystallographic study of vertically aligned and doped ZnO nanorods growth using textured ZnO films produced by ALD José Luis Cervantes 2 , Ricardo Rangel 2 , Eduardo Martínez-Guerra ([email protected]) 1 1 Centro de Investigación en Materiales Avanzados, S.C., Parque de Investigación e Innovación Tecnológica (PIIT), Apodaca, Nuevo León, México. 2 Facultad de Ingeniería Química, Universidad Michoacana de S.N.H., Morelia, Michoacán, México. The synthesis of one-dimensional single crystalline ZnO nanostructures has been of increasing interest due to their promising applications in nanoscale devices. Doped and vertically aligned ZnO nanorod arrays with different aspect ratios were synthesized by hybrid wet chemical route. In this study, it was possible to obtain vertically aligned ZnO nanorods using a method that consists in two steps: i) the growing of a textured ALD film to grow a ZnO seeded surface on glass and silicon single crystals ii) and the nanorod array growth by hydrothermal synthesis. ZnO thin films are firstly produced by means of ALD deposited on glass substrates. Subsequently a hydrothermal method is employed to grow vertical-aligned doped-ZnO nanorod arrays on ZnO films. A textured ZnO layer with preferential direction in the normal c-axes is formed on substrates by the decomposition of diethylzinc (DEZn) to provide nucleation sites for vertical nanorod growth. Doped ZnO nanorods (ZnO-NRs) growth over the substrates was performed by wet chemical procedure in which Zn(NO3)2 and hexamethylenetetramine were used as the main precursors. C6H9O6In, Ru3(CO)12 and Ce(C2H3O2)3 • 1.5H2O compounds were used for doping. Crystallographic orientation of doped ZnO nanorods and ZnO-ALD films was determined by X-ray diffraction analysis. XRD results indicate that the nanorods are high-quality single crystals growing along [0001] direction with a high consistent orientation perpendicular to the substrate which is quantified through the texture coefficient. Composition, morphologies, length, size and diameter of the nanorods were studied using a scanning electron microscope, energy dispersive x-ray spectroscopy (EDS) analyses and atomic force microscopy (AFM). Length and thickness of the ZnO-NRs ranged between 40 and 90 nm and 300 and 600 nm, respectively. It is demonstrated that crystallinity of the ZnO-ALD films plays an important role on the verticalaligned doped ZnO nanorod growth. SEM images in plane and tilted view show that the 64 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla nanorods have smaller average diameters when compared with conventional hydrothermal synthesis. The possible growth mechanism concerning the growth of the different doped ZnO nanorods morphologies through the hybrid method is also discussed. The nanorod arrays synthesized in solution had a diameter, length, density, and orientation desirable for a potential application as nanostructured sensor devices and solar cells. [ ALD-448 ] Fabrication of a flexible dye sensitized solar cell using Atomic Layer Deposition Manuel Meléndrez 2 , Francisco Solís-Pomar 4 , Miguel José Yacamán 3 , Eduardo Pérez-Tijerina 4 , Eduardo Martinez-Guerra ([email protected]) 1 1 Centro de investigación en Materiales Avanzados (CIMAV), Unidad Monterrey-PIIT, Apodaca, Nuevo León, México 66600. 2 Department of Materials Engineering (DIMAT), Faculty of Engineering, University of Concepcion, 270 Edmundo Larenas, Casilla 160-C, Concepcion, Chile 4070409. 3 International Center for Nanotechnology and Advanced Materials (ICNAM), Department of Physics & Astronomy, University of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249, USA. 4 Universidad Autónoma de Nuevo León, Facultad de Ciencias Físico-Matemáticas, San Nicolás de los Garza, Nuevo León 66451, México. Flexible and rigid dye sensitized solar cells (flex-DSSCs) were built using hexagonal-shaped small ZnO nanorods synthesized on PET (Polyethylene terephthalate)/ITO and Glass/FTO substrates. In the synthesis, Atomic Layer Deposition (ALD) was used to deposit a textured ZnO film which acts as seed layer. ZnO nanorods growth was carried out by a chemical method assisted by ultrasound using Zn(NO3)2 and hexamethylenetetramine (HMT) as precursors. The reaction was carried out in two steps: i) ZnO textured film deposition and ii) ultrasound-assisted growth. After, synthesis, aligned ZnO nanorods (ZnO-NRs) with lengths and thicknesses between (240-350 nm) and (25-80 nm) on substrates were obtained and characterized by HRTEM, SAED, EF-SEM, UV-Vis and Raman spectroscopy. Structural analysis revealed that the ZnO nanorods are well crystalline, possessing a perfect hexagonal structure characteristic of Wurtzite zinc oxide with preferential growth in [0001] direction. ZnO-NRs/(PET/ITO) and ZnO-NRs(Glass/FTO) transmittance ranged between 50% and 80%, this variation depended on the synthesis conditions. Optical band-gap of the synthesized materials was approximately 3.3 eV and this value was independent of the nanorods dimensions. Through EF-SEM, it is evidenced that the nanorods grew on ZnO seed layer of 200 nm, which allowed good contact with the conducting surface of the substrate. 65 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla Analyses on the effect of synthesis parameters on NRs growth, fabrication of solar cell prototype using working electrode and collector electrode were formed by (Glass/FTO/ZnOfilm/ZnO-NRs/ruthenium-dye) and (Glass/FTO/Pt-layer) respectively. Experimental details, structural, electrical and optical characterization details are discussed.It is confirmed that these nanorods synthesized by hybrid methods are single crystals of ZnO hexagonal wurtzite type (also seen in the XRD). The observed planes have an inter-planar distance of 0.26 nm corresponding to the (0002) plane. Atomistic models correspond to ZnONRs which are seen from different zone axes. The UV–Vis spectra of glass/FTO/ZnO-ALD-film and glass/FTO/ZnO-ALD-film/ZnO-NRs substrates were recorded. From the UV–Vis spectra, it is observed that when the reaction times increased the percentage of transmittance decreased owing to ZnO-NRs size (diameter and length) increase as well as the ZnO-film on glass/FTO substrates. Higher reaction times both the nanorods size and the protective ZnO-ALD film are greater, this leads to decrease the substrates transmittance and also loss on linearity at energy values near the optical absorption due to increase in the light scattering phenomena. Optical absorption edges of the films did not showed blue shift due to quantum size effect. In addition, experimental results confirmed that the optical absorption depends mainly on the ZnO-NRs deposited on the electrode more than the ZnO-ALD film absorption. Electrical performance for flexible and rigid dye sensitized solar cells (flex-DSSCs) were developed and it will be discussed through presentation. 66 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ ALD-497 ] Synthesis and characterization of TiO2 and HfO2 nanofilm compounds by ALD Heber Hernández-Arriaga ([email protected]) 1 , Eliseo GarciaRamirez 1 , Pierre Giovanni Mani-Gonzalez ([email protected]) 4 , Joel Molina-Reyes 3 , Eduardo Martinez-Guerra 2 , Edgar Lopez-Luna 1 , Miguel Angel Vidal-Borbolla 1 1 Centro de Aplicación de la Radiación Infrarroja, Energías Alternativas y Materiales, Coordinación para la Innovación y Aplicación de la Ciencia y la Tecnología, Sierra Leona 550, Lomas 2a. Sección, San Luis Potosí, C.P. 78210, San Luis Potosí, México 2 Centro de Investigación en Materiales Avanzados Monterrey, Alianza Norte 202. Parque de Investigación e Innovación Tecnológica. Apodaca, C.P. 66600, Nuevo León, México. 3 Instituto Nacional de Astrofísica, Óptica y Electrónica, Luis Enrique Erro 1, Tonantzintla, C.P. 72840, Puebla, México. 4 Instituto de Ingeniería y Tecnología, Departamento de Física y Matemáticas, Universidad Autónoma de Ciudad Juárez, Ave. Del Charro 450, Cd. Juárez. C.P. 32310, Chihuahua, México. Hafnium Oxide (HfO2) and Titanium oxide (TiO2) films are being studied for their high-k constant in CMOS applications. Atomic layer deposition (ALD) is a novel technique used to deposit oxides, metals and nitrides with high quality and control thickness. Some applications for HfO2 and TiO2 are optical coatings, sensors and MOSFETs. The HfO2-TiO2 nanofilm compounds were synthetized through Tetrakis(dimethylamido)hafnium(IV) and Tetrakis(dimethylamido)titanium(IV) as precursors and H2O as oxidant-agent varying substrate temperature (120 °C, 200 °C and 250 °C). X-Ray Reflectivity (XRR) and Spectroscopic Ellipsometry (SE) were used to determine HfO2 and TiO2 compound thickness and dielectric function respectively. Stoichiometric films were studied with X-Ray Photoelectron Spectroscopy (XPS). Leakage current and dielectric constant were studied through I-V, C-V measurements respectively. 67 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla ADVANCED AND MULTIFUNCTIONAL CERAMICS (AMC) Chairman: Jesus Heiras Aguirre (CNYN-UNAM) Sesión Oral [ AMC-81 ] Synthesis and characterization of ferroelectric films polymer- ceramic composite (PMMA PZT, BZT,BNT) Tonatiuh Escamilla Díaz ([email protected]) 1 , José Martín Yáñez Limón ([email protected]) 1 , Rafael Ramírez Bon 1 1 CINVESTAV Unidad Querétaro There is currently a great interest in organic and inorganic hybrid materials due they present very interesting structural, optical and electrical properties. Other materials of great interest are the piezo – composites based in ferroelectrics, which consists of two phases: a matrix and other dispersed. The effective properties depend on a variety of factors such as chemical composition, distribution, microstructure, etc. and they are a function of the constituent phases. In this work we synthesized hybrid materials films of PMMA – TiO2 - PZT, by sol-gel, which is a quite convenient method to prepare this class of materials. It is possible obtain a high control of the chemical composition of the hybrid at low temperatures and a large area. The films were deposited on glass for optical characterization, and ITO-glass for electrical measurements. Methods for depositing the hybrid materials were spin coating and dip coating. In case of spin – coating the speed was 1500rpm during 1 minute, on the other hand the speed for dip coating was 6cm/min. Similarly composite thin films were synthesized with a matrix of PMMA - TiO2 plus an aggregate of PZT particles at different concentrations. Structural characterization, optical and electrical were also performed using different techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-VIS spectroscopy, etc. The purpose of this study was to evaluate the optical and dielectric properties at different concentrations in volume in the case of hybrid materials. That at low concentrations resulting 68 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla PZT, between 10 and 30%, they have poor optical properties, whereas at high (50 to 60%) concentrations improve their properties. In the case of composite material PMMA – TiO2 with PZT particles the aim it is to evaluate its ferroelectric and dielectric properties, between dielectric and ferroelectric phase with different PZT concentrations: 0, 2.5, 5, 7.5 and 10% by weight . Best results have been observed in films deposited by dip-coating in both uniformity and dispersion of the particles with size between 80 and 90nm. Also interesting results have been observed in the hysteresis loops measured at different electric fields and polarization increases according increases the field due to the influence of PZT´s particles. [ AMC-214 ] Effect of CdO in the structure and optical properties of germanate-tellurite glasses Carlos Guadalupe Pérez-Hernández 3 , María Elena Zayas 4 , Josefina Alvarado-Rivera ([email protected]) 2 , David Alejandro Rodríguez-Carvajal 3 , María Betsabé Manzanares-Martínez 3 , Mario Enrique Álvarez 3 , Rosendo Lozada-Morales 1 1 Benemérita Universidad Autónoma de Puebla, Postgrado en Física Aplicada, Facultad de Ciencias Físico-Matemáticas, Av. San Claudio y Av. 18 Sur, Col. San Manuel, Ciudad Universitaria, Puebla, Pue C. P. 72570, México. 2 Cátedras Conacyt, Departamento de Investigación en Física, Universidad de Sonora, Blvd. Encinas y Rosales S/N, Col. Centro, C. P. 83000, Hermosillo, Sonora, México. 3 Departamento de Física, Universidad de Sonora, Blvd. Encinas y Rosales S/N, Col. Centro, C. P. 83000, Hermosillo, Sonora, México 4 Departamento de Investigación en Física, Universidad de Sonora, Blvd. Encinas y Rosales S/N, Col. Centro, C. P. 83000, Hermosillo, Sonora, México. Germanate and tellurite glasses are widely known materials for its applications in telecommunications and mid-infrared fibers. These oxides display properties like high linear and nonlinear index, broad band transmission from the visible into the infrared, low phonon energy, high refractive index, which are very desirable for IR technologies, non-linear optics and design of laser devices. In this work, glasses from the novel CdO-TeO2-GeO2 ternary system are investigated. A set of samples varying the cadmium oxide content from 10 to 80% wt was fabricated by conventional melt-quenching method at 1350°C. Glasses of different colorations from yellowish to brilliant orange were obtained, the later corresponded to the glass with the highest content of cadmium oxide. X-ray diffraction results demonstrated the 69 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla amorphous nature of the samples and evidenced that only two glasses presented partial crystallization of CdTeO3 and Cd3 Al2 (GeO4)3 phases. Infrared spectra analysis shows the characteristic absorption peaks of GeO6 (520-470 cm -1) and Cd-O (440-420 cm-1) bonds vibration; and in the range of 800-600 cm-1 a broad and weak band related to Te-O-Te bonds vibration. Raman spectra displays two main bands at 980-670 cm-1 and 640-370 cm-1, which are related to stretching vibrations Te-O of TeO4 units and Ge-O-Ge bonds in 4- and 3membered GeO4 rings, respectively. CdO is a modifier oxide that will influence structural changes in the glass matrix, this effect is noticed in the shift to lower wavenumber values of the band at 980-670 cm-1 corresponding to TeO3/TeO3+1 units. For a more thorough analysis of the structural changes, X-ray photoelectron spectroscopy of the glasses with the lowest and highest contents of cadmium oxide was performed. High resolution analysis of the O 1s, Ge 3d, Cd 3d and Te 3d photoelectron lines was realized to determined changes in coordination and oxidation states of the cations. Moreover, non-bonding and bonding oxygen ratio of the glasses was estimated. Finally, optical absorption spectra of the glasses and estimation of the energy band gap of all samples were carried out. Results show that as the content of CdO increase the energy band gap of the glasses decrease. [ AMC-269 ] Influence in luminescence of type of doped in perovskite. María Dolores Durruthy-Rodriguez ([email protected]) 1 1 CINVESTAV-Querétaro, IPN, Libramiento Norponiente 2000, Fracc. Real de Juriquilla, CP 76230, Santiago de Querétaro, Querétaro, México. Applied Physic Department, Cybernetic, Mathematics and Physics Institute, CITMA, 15 # 551, Vedado, La Habana, Cuba, The ferroelectric materials have been recognized by their multifunctional physical properties; inside them, their optic properties are investigation object due to their possible applications, the photoluminescence is a very interesting phenomenon that appears in these materials. In this work interesting results are presented from the luminescent emission to room temperature of perovskitas ABO3, in the systems doped PZT and KNN, in A and B site of the structure. The main emission bands in PZT appear around 1.73, 1.87, 2.5, 2.66 and 3.03 and at 1.86, 2.19, 2.31 and 2.5 eV for the system KNN, the excitement bands in all the cases were 373, 457, 500 and 680 nm. The so much voltages of the lamp were measured like of the samples to the different longitudes of excitement wave. The perovskitas free of lead presents a promissory increment of the luminescent emission. 70 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ AMC-292 ] Nanostructured cerium oxide thin films deposited by ultrasonic spray pyrolysis. Mario Fidel García Sánchez ([email protected]) 2 , Ismael Ponce Rosas 1 , Guillermo Santana Rodríguez 1 , Betsabée Marel Monroy Peláez 1 1 Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México. A.P. 70-360, Coyoacán, C.P. 04510, México D.F. 2 Unidad Profesional Interdisciplinaria de Ingeniería y Tecnologías Avanzadas, Instituto Politécnico Nacional, Av. IPN No 2580, Gustavo A. Madero, C.P. 07340, México D.F. Nanostructured thin films of cerium oxide have been prepared on single-crystalline silicon substrates by ultrasonic spray pyrolysis using cerium acetylacetonate as metallo-organic precursors dissolved in anhydrous methanol. The morphology, structure and electrical properties were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), ellipsometry, and impedance spectroscopy (IS). The substrate temperature was optimized for obtaining smooth, dense and homogeneous nanocrystalline films with grains sizes as small as 10 nm. XPS measurements shows a mix of Ce4+ and Ce3+ into the as grown samples, regardless of the substrate temperature. The influence of thermal annealing on structural properties of films was evaluated. The small grain size decrease the activation energy and the conductivity of these obtained materials. Acknowledgements This work has been partially supported by IPN with research project 201500044. The authors want to thank to C. Flores, O. Novelo, J. Romero, L. Lartundo and J. A. Andraca for technical assistance. Keywords: ceria thin films, nanostructure, ultrasonic spray deposition. 71 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ AMC-329 ] Synthesis of lanthanum nickelite based perovskite by mechanosynthesis and urea combustion methods Luis Alberto Mendoza de la Rosa ([email protected]) 2 , Antonia Martínez Luévanos ([email protected]) 2 , Martín A. Hernández Landaverde 1 , Sergio J. Jiménez-Sandoval 1 , Brenda R. Cruz Ortiz 2 1 2 Cinvestav-IPN; Unidad Querétaro Materiales Cerámicos; Universidad Autónoma de Coahuila; Blvd. V. Carranza s/n, Rep. Ote., Saltillo, Coah. México. CP 25280 In this work the synthesis of lanthanum nickelite (La1-xMxNiO3±δ) by the methods of mechanosynthesis and urea combustion was investigated. The characterization technique of X-ray diffraction was used to evaluate the effect of temperature and thermal treatment time on perovskite formation and on its purity. According to the XRD patterns of the samples obtained by mechanosynthesis, the better result was obtained at 900 ° C, using a time of 10 hours; in the other hand, by combustion method it found that the perovskite phase was obtained at 900 °C, but using a time of 5 hours. The best result was obtained by the urea combustion method. 72 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ AMC-335 ] Evaluation of Corrosion on Borided and Non-borided alloy Co-Cr-Mo ASTM F75 immersed in Hanks’ solution. Maria Guadalupe Rosas Becerra ([email protected]) 1 , Ivvone Mejía Caballero 1 , Jose Martinez Trinidad ([email protected]) 1 , Manuel Palomar Pardave 2 , Ivan Enrique Campos Silva 1 1 Instituto Politécnico Nacional, Grupo Ingeniería de Superficies, SEPI-ESIME, U.P. Adolfo López Mateos, Zacatenco, 07738 México, DF, México 2 Universidad Autónoma Metropolitana, Av. San Pablo No. 180, Azcapotzalco, 02200 México, DF, México The corrosion resistances of borided and non-borided cobalt alloy immersed in a simulated body fluid were evaluated in this study. The boriding process was performed using the powder-pack method at a 1223 K with 6 h of exposure. The corrosion tests were assessed using Potentiodynamic Polarization technique, in which the samples were evaluated during 10 days of inmersed in the Hanks’ solution. After the tests, borided and non-borided samples were analyzed by Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray Spectrometry (EDS) to determine the corrosion mechanisms and the chemical composition over the surfaces, respectively. According to the polarization resistance curves, the boride cobalt alloy provided a reasonable corrosion resistance notwithstanding, the non-borided cobalt alloy exhibited higher resistance value. The main corrosion mechanism was pitting corrosion observed on the borided cobalt alloy by SEM technique and the principal of alloy elements of boronized samples from surface was determined using EDS. It was concluded that the decrease of corrosion resistance of boride cobalt alloy was caused by presence of sulfates and phosphates over the materials surface, which were contained in provides the Hanks’ solution. 73 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla INVITED TALK [ AMC-484 ] Second harmonic generation in Lithium Niobate nanoparticles Oswaldo Sanchez Dena 1 , Emma García-Ramírez 1 , Jose Trinidad Elizalde-Galindo 3 , Pierre Giovanni Mani-Gonzalez 3 , Enrique ViguerasSantiago 2 , Jorge Alejandro Reyes-Esqueda 1 , Rurik Farías ([email protected]) 3 1 Instituto de Física, Universidad Nacional Autónoma de México, 04510, México, D. F., México 2 Laboratorio de Investigación y Desarrollo de Materiales Avanzados, Universidad Autónoma del Estado de México, Paseo Colón esquina Paseo Tollocan, Toluca, Estado de México, 50000, México 3 Universidad Autónoma de Ciudad Juárez, Av. Del Charro 450 Norte, Ciudad Juárez, Chihuahua, 32310, México We study second harmonic generation (SHG) in lithium niobate (LiNbO3) nanoparticles as a function of the fundamental wavelength (800-1300 nm) and polarization angle. LiNbO3 nanocrystals were synthesized by means of a mechanochemical reaction using lithium carbonate and niobium oxide; three different samples were obtained by this method. Structure as well as composition of all the samples was verified by means of non-destructive characterization techniques such as X-Ray Diffraction (XRD) and Raman spectroscopy. Results of SHG show a maximum conversion efficiency of 1.37%, which corresponds to the harmonic intensity at a fundamental wavelength of 1070 nm, also was not found a clear dependency upon polarization angle of the incident light. 74 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla Sesión Poster [ AMC-37 ] Hot corrosion analysis of NiCoCrAlY/7YSZ coatings deposited by air plasma spray (APS) on a nickel based superalloy Nathalia Diaz Vallejo ([email protected]) 2 , Oscar Sanchez 2 , Julio Cesar Caicedo 3 , William Aperador 1 , Gustavo Zambrano 2 1 Departament of Engineering, Universidad Militar Nueva Granada, Bogotá-Colombia 2 Thin Films Group, Department of Physics, Universidad del Valle, Cali-Colombia 3 Tribology, Powder Metallurgy and Processing of Solid Recycling Research Group, Universidad del Valle, Cali-Colombia In this study, hot corrosion performance and the damage mechanism of air plasma-sprayed (APS) yttria-stabilized zirconia (YSZ) in contact with corrosive salts (vanadium pentoxide V2O5 and sodium sulfate Na2SO4) were investigated at 700°C evaluated using electrochemical impedance spectroscopy (EIS) and Tafel analysis. The EIS data were interpreted based on proposed equivalent electrical circuits using a suitable fitting procedure elaborated by Echem Analyst™ Software. The EIS spectra were fit to the traditional model for metal coated with a porous, non-conductive coating where the capacitors were replaced with constant-phase elements. The impedance measurement of YSZ ceramic at 700°C in this test gives impedance spectra with a single semicircle. The resistance of YSZ coat comes from the contribution of the YSZ grain. Phase transformations and microstructural development were examined using X-ray diffraction (XRD), with Rietveld refinement for quantitative phase analysis, and scanning electron microscopy (SEM) that indicated that the reaction between sodium vanadate (NaVO3) and yttrium oxide (Y2O3) produces yttrium vanadate (YVO4) and leads to the transformation of tetragonal to monoclinic zirconia phase. 75 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ AMC-88 ] Effect of thermal treatment on the luminiscence of Eu3+ doped ZnO-CdO-TeO2 glasses Iveth Viridiana García Amaya ([email protected]) 3 , María Elena Zayas Saucedo 4 , Josefina Alvarado Rivera 2 , Mario Enrique Álvarez Ramos 3 , Rosendo Lozada Morales 1 1 Benemerita Universidad Autónoma de Puebla, Postgrado en Física Aplicada, Facultad de Ciencias Físico-Matemáticas, Avenida San Claudio y Avenida 18 Sur, Colonia San Manuel, Ciudad Universitaria, 72570 Puebla, PUE, México 2 Cátedras Conacyt, Departamento de Física, Universidad de Sonora, 83000 Hermosillo, SON, México 3 Departamento de Física, Universidad de Sonora, 83000 Hermosillo, SON, México 4 Departamento de Investigación en Física, Universidad de Sonora, 83000 Hermosillo, SON, México A series of europium doped glasses in the ternary system 10ZnO·30CdO·60TeO2 have been synthetized by the conventional melt-quenching method at 1000°C by 30 minutes, varying the concentration of europium nitrate (Eu(NO3)3.6H2O) from 0.3 to 1.5 % mol. In this work a study of the optical and structural differences of the as-cast and heat-treated glasses is presented. The structural studies reveal the presence of amorphous phase for both set of samples detected by DRX. FT-IR spectra of the as-cast glasses shows the decomposition of TeO4 units in TeO3+1/TeO3, while in the heat-treated glasses the TeO4, units are reconstituted. This effect can be probably caused by the reincorporation of O2 molecules trapped in the interstices into the glass matrix. The intensity of the band localized around 1556 cm-1 in Raman spectra decrease considerably after the thermal treatment.. Photoluminescence spectra of both set of glasses exhibit emissions from the transition of Eu3+ ion: 5D2→7F0 (468 nm), 5D2→7F2 (490 nm), 5D2→7F3 (511 nm), 5D1→7F1 (536 nm), 5 D1→7F2 (554 nm), 5D0→7F0 (579.5 nm), 5D0→7F1 (592 nm), 5D0→7F2 (613 nm), 5D0→7F3 (652 nm), y 5D0→7F4 (490 nm). It is noticeable, the presence of the band associated with the 5 D0→7F0 transitions, which it is only permitted when Eu3+ ions are occupying positions of low symmetry. This, together with the fact that the band corresponding to the transitions 5 D0→7F2 dominated the emission spectra, excludes the possibility that it Eu3+ ions are in a position of high symmetry. 76 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ AMC-228 ] STRUCTURAL STUDY AND PHOTOLUMINESCENCE OF Cd3Al2Ge3O12 PHASE IN GLASSES OF CdO-TeO2-GeO2 SYSTEM Carlos Guadalupe Pérez Hernández ([email protected]) 1 , Josefina Alvarado Rivera ([email protected]) 1 1 Unison A series of glasses of the CdO-TeO2-GeO2 system varying CdO and GeO2 composition were fabricated. Reagent grade oxide powders of high purity were used for glass preparation by melt-quenching method in high alumina crucibles at 1350°C. Some of the obtained glasses presented crystallization of a white phase identified by XRD as a cadmium-aluminum germanate (Cd3Al2Ge3O12). The formation of this compound is attributed to the crucible corrosion during fusion leading to an incorporation of aluminum in the melt. It was previously reported that the cadmium-aluminum germinate doped with Dysprosium displayed phosphorescence under UV light excitation. In this work, a structural study and luminescence properties of the cadmium-aluminum germanate were studied by means of Xray diffraction (XRD), Raman spectroscopy and photoluminescence. XRD confirmed the formation of this phase in the samples with higher contents of cadmium oxide. Raman spectroscopy was performed with both 488 and 632 nm laser lines, it revealed that the material is excited with the red laser and shows a wide emission band in the infrared region. Photoluminescence measurements were carried using a UV excitation light of 254 nm. Results show that the emission chromatic coordinates are located near the white light region in the CIELAB chromaticity diagram. This material has potential applications as white-light emitting diodes. 77 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ AMC-305 ] Influence of La doping in multiferroic properties of LiNbO3 nanoparticles Carlos Alejandro Diaz Moreno ([email protected]) 2 , Abel HurtadoMacias 1 , Jorge Portelles 3 , Jesús Heiras 4 , Enrique Ramirez 2 , Jorge Lopez 2 1 Centro de Investigación en Materiales Avanzados S.C., Laboratorio Nacional de Nanotecnología, Miguel de Cervantes 120, Complejo Industrial Chihuahua, Chihuahua, Apdo. Postal 31109 México 2 Department of Physics of University of Texas at El Paso, 500 W. University Ave, El Paso TX 79968 3 Facultad de Física, Universidad de La Habana, San lázaro y L, 10400, Cuba 4 Universidad Nacional Autónoma de México, Centro de Nanociencias y Nanotecnología, Km 107 Carretera Tijuana-Ensenada, Ensenada, B.C. 22860 In this work we reported an enhancement of the ferroelectric and ferromagnetic properties when LiNbO3 doped with lanthanum. Lithium niobate doped with lanthanum (La0.05Li0.85NbO3) was prepared by mechanical milling method using lithium carbonate, niobium oxide and lanthanum oxide as precursors [1]. After 12 hours of alloying, the sample was calcinated at 900ºC in order to remove carbonate residues. A second milling of 8 hours was done to reduced particle size obtaining an average size of 70±5 nm. Result from X-ray diffraction indicates the formation of ferroelectric phase obtained in air atmosphere with spherical shape as confirmed by TEM micrographs. Raman and X-ray fluorescence spectroscopy were performed in order to indicate new vibrations modes and elemental analysis quantification respectively. To investigate the ferroelectric properties, the nanoparticles were binded with PVA and pressed at 105 kg/cm2 to conform pills with a diameter of 11.7 mm and a distance between plates of h=1 mm. The ferroelectric properties were obtained at room temperature using a RADIANT RT-66ª equipment. The hysteresis loops show a Ps= 0.235 μC/cm2, Pr= 0.141 μC/cm2 and Ec= 1.35 kV/cm values for La0.05Li0.85NbO3 sample. And the values for Ps= 0.0701 μC/cm2, Pr= 0.0382 μC/cm2 and Ec= 391 kV/cm when compared to pure lithium niobate. The ferromagentic curves, measured in a 9T Quantum Design VSM PPMS at room temperature. The measured mass sample was of 24.3 mg for both samples. The values for saturation magnetic moment are of 2.5 × 10−3 emu for La0.05Li0.85NbO3 and 1.4 × 10−3 emu when compared to pure lithium Niobate. [1] Díaz-Moreno, C.; Farias, R.; Hurtado-Macias, A.; Elizalde-Galindo, J.; Hernandez-Paz, J. Multiferroic response of nanocrystalline lithium niobate. J. Appl. Phys. 2012, 111, doi:10.1063/ 1.3673434. 78 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ AMC-341 ] Thermal Stability and Sinterability of Ce0.8Sm0.2O2- δ, Ce0.8Sm0.15Ca0.05O2-δ and Ce0.8Sm0.19Cu0.01O2-δ ionic conductors César Gustavo Mendoza Serrato ([email protected]) 1 , José Ortiz Landeros 1 , Carlos Gómez Yáñez 1 1 Departamento de Ingeniería en Metalurgia y Materiales Escuela Superior de Ingeniería Química e Industrias Extractivas, IPN, UPALM Av. Instituto Politécnico Nacional S/N CP 04510, México D.F. Ceria-based ceramic oxides are utilized as automotive exhaust catalysts, as catalysts in fuel cells and as cathode, anode, and electrolyte materials in solid oxide fuel cells among others [1-2]. The present work is a detailed study on the preparation and characterization of a series of Ceria-based ceramic materials having ionic conductivity properties at intermediate temperatures between (700-900 ° C). In this sense, materials with chemical formula of Ce0.8Sm0.2O2-δ, Ce0.8Sm0.15Ca0.05O2-δ and Ce0.79Sm0.2Cu0.01O2-δ were synthesized by the citrate complex precursor method and then were subjected to thermal and chemical stability tests under CO2 rich atmosphere. The structural and microstructural characterization of the different samples was conducted by X-ray diffraction (XRD), infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and ionic conductivity measurements. The thermal stability study was conducted under a CO2 atmosphere at high temperature (9001300 oC). The results suggest the effectiveness of citrate precursor method to incorporate the dopant (Ca+2, Cu2+) in the fluorite structure of the Ceria. Additionally, results show a remarkable effect of doping on both, the ionic conductivity, and stability properties. For example, it was observed that incorporation of Ca2+ in the material increases the ionic conductivity values and sinterability properties thereof. On the other hand the addition of Cu2+ cation has an effect on the microstructural features of the material by reducing the mean grain size obtained after sintering process. [1] Masatomo Yashima, Some recent developments in the atomic-scale characterization of structural and transport properties of ceria-based catalysts and ionic conductors, Catalysis Today, 253 (2015) 3-19. [2] F. Rahmawati, W. Fajriati, E. Heraldy, D. Gustaman-Syarif, Oxygen Ion-Conductivity and Chemical Stability of Ceria Based-Electrolyte in Composite with Sodium Carbonate as Electrolyte for Direct Biodiesel-Fuel Cells, Procedia Chemistry, 14 ( 2015) 164-170. 79 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ AMC-392 ] CO2 sorption-desorption analyses on different of Li2O-Bi2O3 ceramics Eva Marina Briz Lopez ([email protected]) 1 , Jose Ortiz Landeros 1 , Issis Caudette Romero Ibarra 2 , Cesar Gustavo Mendoza Serrato 1 1. Departamento de Ingeniería en Metalurgia y Materiales, Escuela Superior de Ingeniería Química e Industrias Extractivas, IPN, Av. Instituto Politécnico Nacional s/n, CP 07738 México DF, México 2. Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa, México D.F., México. Av. San Rafael Atlixco # 186 Col. Vicentina C.P. 09340 Ceramic sorbents from the Li2O-Bi2O3 system have been studied as potential CO2 captors. In the present research, ceramic sorbents were synthesized by the conventional solid state reaction method. The different sorbents were synthesized from Bi2O3 and Li2O oxides and completing the reaction between oxides in dry air stream at 700 ° C. The influence of the different experimental conditions, such as temperature and CO2 partial pressure on the CO2 absorption capacity, were studied. The structural and microstructural characterization of materials was conducted by X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. Furthermore, the CO2 absorption capacity and reaction rate as well as thermal stability of the different materials were evaluated by thermogravimetric analysis (TGA). The obtained results showed the obtaining of the pure phase of differents lithium bismuthates Li7BiO6, Li5BiO5, Li3BiO4 and LiBiO3. Specifically, Li7BiO6 shows a theoretical CO2 capture of 9.8 mmolCO2 g-1 in a temperature range of 275 to 575 ° C. Additionally, Li7BiO6 shows the capability to capture CO2 at very low CO2 partial pressure values. [1] M. J. Ramírez-Moreno, I. C. Romero-Ibarra, J. Ortiz-Landeros, H. Pfeiffer, Alkaline and alkaline-earth ceramic oxides for CO2 capture, separation and subsequent catalytic chemical conversion. In: Claudia do Rosario Vaz Morgado and Victor Paulo Pecanha Esteves, editors, CO2 Sequestration and Valorization, InTech Open Acces; 2014. [2] Ke Wang, Pengfei Zhao, Xin Guo, Yimin Li, Dongtai Han, Yang Chao; Enhancement of reactivity in Li4SiO4-based sorbents from the nano-sized rice husk ash for high-temperature CO2 capture; Energy Conversion and Management; 2014. 80 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ AMC-459 ] Structure and optical studies of perovskite Bi2Fe2Ga2O9 V. L. Medina-Llamas ([email protected]) 1 , M. F. JassoJasso 1 , J. J. Ortega-Sigala 1 , F. Puch-Ceballos 1 , A. Puga 1 , L. PérezArrieta ([email protected]) 1 1 Unidad Académica de Física. Universidad Autónoma de Zacatecas. Calz. Solidaridad Esq. Paseo La Bufa s/n. C. P. 98060. Zacatecas, Zac. The phase diagram of system pseudo-ternary (Bi2O3–Fe2O3-Ga2O3) provides condition of composition and temperature for the growth of single crystal such as BiFe1/2Ga1/2O3 and Bi2Fe2Ga2O9. In this work a single crystals of Bi2Fe2Ga2O9 of perovskite structure were grown with dimensions greater than 1 mm from a Bi2O3 flux by Crystal Growth from High-temperature Solutions Method. It is known that Bi2Fe2Ga2O9 mixed oxide crystals have a habit and orthorhombic symmetry (Pbam). However, we obtained crystals of brown-dark color with monoclinic habit in the same conditions reported for other authors. The X-ray diffractometry method was used in this compound in powder form to refine the structure by the Rietveld method. The monoclinic structure parameters obtained are: a = 9.739 Å, b = 11.941 Å, c = 7.122 Å and beta = 93.382o Å, V = 826.80 Å3, and Space grupo P2/m. Structural data already published are compared with our results, also measurement results by means of optical and electron microscopy are presented. 81 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ AMC-465 ] Structural and morphological characteristics of compounds in the partial phases diagram of Bi2O3–Fe2O3–Ga2O3 system B. Villaneda-Saldívar ([email protected]) 2 , J. J. Araiza-Ibarra 2 , A. B. Soto-Gúzman 1 , E. García-Jaramillo 2 , A. Puga 2 , L. Pérez-Arrieta ([email protected]) 2 1 Departamento de Física. CINVESTAV-IPN. Av. Instituto Politecnico Nacional 2508, Delegación Gustavo A. Madero, Col.San Pedro Zacatenco,C. P. 07360 Ciudad de México, D.F. 2 Unidad Académica de Física. Universidad Autónoma de Zacatecas. Calz. Solidaridad Esq. Paseo La Bufa s/n. C. P. 98060. Zacatecas, Zac. Novel ferroelectric materials base on oxides Bi2O3 are specially important due to the electric and magnetic properties they exhibit and make them useful to as a data storages devices. In this work, we search for the powder formation of Bi2(Fe1/2Ga1/2)O3 (BFGO). The typical temperatures, structural and morphological characteristic in Bi2O3–Fe2O3-Ga2O3 pseudoternary phase diagram were evaluated with high-purity starting materials. The synthesis starting from a simple oxides is carrying out by applying the Solid State Chemical Reaction method. We focus in partial region of mole composition from 90:5:5 to 50:25:25. The X-ray diffraction of samples demonstrated the presence of different phases based in Bi2O3 ( and ) and perovskites structures analogous to BiFeO3 (113) y Bi2Fe4O9 (249) when are doped with Ga+3, Bi(Fe1/2Ga1/2)O3 y Bi2Fe2Ga2O9. Differential thermal and thermo-gravimetry analysis (DTA-TGA) data makes it possible to present phase changes in the sample when the temperature and chemical compositions is changed. Finally scanning electron microscopy shows the morphological changes in the crystals. The sintered specimen with 11.5 mol % Fe2O3 and 11.5 mol % Ga2O3 in the Bi2O3-Fe2O3-Ga2O3 system showed a 113-phase in its as-sintered specimen. 82 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ AMC-473 ] CeO2-based mixed oxides for the catalytic soot combustion for diesel engines Wendy Téllez-Salazar ([email protected]) 1 , José Ortiz-Landeros ([email protected]) 1 , César Mendoza-Serrato 1 , Carmen Mertínez-Mancilla 1 , Heriberto Pfeiffer 1 1 Departamento de Ingeniería en Metalurgia y Materiales Escuela Superior de Ingeniería Química e Industrias Extractivas, IPN, UPALM Av. Instituto Politécnico Nacional S/N CP 04510, México D.F Diesel engines have high energy efficiency, but emit particulate carbonaceous material commonly known as soot, which is responsible for severe issues of environmental pollution and health damage. For example, such a material may be causing the development of cancer, cardiovascular and respiratory effects as well as air, water and soil pollution [1]. The technology of particle filters, in combination with oxidation catalysts appears to be one of the most efficient techniques for treating this issue. The challenge is to find a catalyst in which soot combustion takes place at a lower oxidation temperature. Several types of catalysts for soot combustion have been extensively studied. Catalysts containing precious metals, alkali metal oxides, perovskites and most recently ceria-based catalyst are examples of the aforesaid. In fact, the metal oxides based on ceria have been widely used as oxidation catalysts due to its oxygen storage capacity [2]. In the present research work, a series of CeO2-based oxides were synthesized and proposed as possible catalysts for soot combustion. Binary and ternary mixed oxides with composition Ce/Zr, and Ce/Zr/Y with different proportions were obtained via the citrate precursor method. Prepared materials were characterized by X-Ray Diffraction (DRX), BET and Infrared spectroscopy (FT-IR) and TPD techniques. Additionally the oxidation ability of these materials for soot combustions was evaluated by thermogravimetric analyses (TGA). [1] R. Prasad, V. Rao, A Review on Diesel Soot Emission, its Effect and Control, Bulletin of Chemical Reaction Engineering & Catalysis, 5 [2] (2010) 69 – 86. [2] Y. Wei and Z. Zhao, Preparation of ultrafine Ce-Based oxide nanoparticles and their catalytic performances for diesel soot combustion, Journal of Rare Earths, 32 [2] (2014) 124130. 83 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ AMC-479 ] Ultrasonic Spray Pyrolysis Deposition of BiFe1-xCrxO3 Thin Films César Gustavo Mendoza Serrato ([email protected]) 1 , Alexis Esteban López López 1 , José Ortiz Landeros 1 , Carlos Gómez Yáñez 1 1 Departamento de Ingeniería en Metalurgia y Materiales Escuela Superior de Ingeniería Química e Industrias Extractivas, IPN, UPALM Av. Instituto Politécnico Nacional S/N CP 04510, México D.F. Multiferroic materials have a great potential to the design of electronic devices. The more interesting features of a multiferroic material is the ability to shows parallel several properties such as ferromagnetism, ferroelectricity, ferroelasticity etc.[1] Recently, there are exhaustive research studies regarding the bismuth ferrite (BiFeO3), which is a multiferroic material showing magnetic behavior. These interesting properties are able to be improved through the structural and microstructural control of the material. An example of the aforesaid is the material´s doping with different metal cations such as Cr, Ni and Co among others. [2]. Several synthesis pathways have been reported to obtain both powders and thin films made of the pure phase of bismuth ferrite such as sol-gel, sputtering, Pechinni and hydrothermal crystallization methods [34]. The present work shows a systematic study regarding the fabrication of BiFeO3 thin films via Spray Pyrolysis method. A series of homogeneous, crystalline and submicrometric films of bismuth ferrite with general formula BiFe1-xCrxO3 were prepared with 0.02<x< 0.1 values. The effect of different processing variables such as precursor concentration, temperature of deposition, precursor concentration, flow rate of the carrier gas and spray to substrate length on the film characteristics were studies by applying a Taguchi robust design. The obtained thin films were characterized by DRX, SEM and AFM techniques among others. Results suggest the potential of this simple and affordable spray pyrolysis technique to the fabrication of good quality BiFeO3 thin films. [1] Samar Layek, H. C. Verma, Magnetic and dielectric properties of multiferroic BiFeO3 nanoparticles synthesized by a novel citrate combustion method, Adv. Mat. Lett., 3 [6] (2012) 533538. [2] Amit Kumar, K.L. Yadav,Magnetic, magnetocapacitance and dielectric properties of Cr doped bismuth ferrite nanoceramics, Materials Science and Engineering: B, 176 [3] (2011) 227–230. [3] D. Wang, M. Wang, F. Liu, Y. Cui, Q. Zhao, H. Sun, H. Jin, M. Cao, Sol–gel synthesis of Nddoped BiFeO3 multiferroic and its characterization, Ceramics International, 41 [7] (2015) 8768– 8772. [4] Chao Chen, Hydrothermal synthesis of perovskite bismuth ferrite crystallites, Journal of Crystal Growth, 291 [1] (2006) 135–139. 84 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ AMC-511 ] Studies on the thermal stability of Ce0.85Sm0.15O2-Sm0.6Sr0.4Al0.3Fe0.7O3- carbonate composites for possible use in the fabrication of ceramiccarbonate dual phase membranes Oscar Ovalle ([email protected]) 2 , José Ortiz-Landeros 1 , Heriberto Pfeiffer 3 1 ESIQIE, IPN IIM, UNAM 3 IIM,UNAM 2 Emissions of greenhouse gases, mainly carbon dioxide (CO2), have increased excessively in recent years mainly due to the burning of fossil fuels causing climate change. Some studies are oriented to implement strategies to mitigate CO2 emissions to the atmosphere [1-2]. For example, a novel mechanism that has been developed in recent years is based on the use of a dual phase ceramiccarbonates membranes. These composite membranes have high CO2 selectivity and high temperature stability. Briefly, the CO2 diffusion through the membranes involves the transportation of O2- ions through the crystalline ceramic phase where the O2- ions react with the CO2 to form CO32- ions; parallely, the CO32- ions will be transported through molten carbonates of the ceramic-carbonate composite. The main issues to design this kind of membranes are the thermal stability and low ionic conductivity of the ceramic phase. Actually, oxygen ionic conductivity is the limiting process for the CO2 permability [3]. Based on the above, the aim of this work is to study the chemical and thermal stability in CO2 atmosphere at high temperature as well as the ionic conductivity properties of the Ce0.85Sm0.15O2-Sm0.6Sr0.4Al0.3Fe0.7O3-Carbonate composite. Recent studies involving this composite have shown that it is a good ionic conductor at high temperatures making it an excellent candidate to prepare dual phase membranes for high temperature CO2 permeation. Composites materials were prepared via citrate precursor method and subsequently characterized by XRD, SEM and Thermogravimetric (TGA) analyses. Thermal stability and sinterability of the material in the temperature range of 700-1300 ºC was studied. Additionally, the prepared material was subject to a long-term stability test under CO2 atmosphere. The obtained results suggest the high potential of the proposed composite material to be used for the preparation of dual phase membranes. [1] C. W. Jones et al. ChemSusChem (2009), 2, 796 – 854 [2] Pfeiffer, H., 2010. Advances on alkaline ceramics as possible CO captors. In: YunHang, H. (Ed.), Advances in CO2 Conversion and Utilization. ACS Symposium Series, vol. 1056. American Chemical Society, Washington DC, USA. [3] J. Ortiz-Landeros et al. Chemical Engineering Science 104 (2013) 891–898 85 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ AMC-517 ] New Approach To The Synthesis of Lithium Niobate Nanoparticles Isis Maria Cota-Martínez 2 , Karina Patricia De La Torre Saenz 2 , Oswaldo Sanchez-Dena 1 , José Trinidad Elizalde-Galindo 2 , Pierre Giovanni ManiGonzalez 2 , Rurik Farías ([email protected]) 2 1 Instituto de Física, Universidad Nacional Autónoma de México, 04510, México, D. F., México 2 Universidad Autónoma de Ciudad Juárez, Av. Del Charro 450 Norte, Ciudad Juárez, Chihuahua, 32310, México A facile hybrid physical/chemical approach is reported to synthetizing lithium niobate nanoparticles (LNNs). The approach involves mechanic activation of each precursor (Lithium Carbonate and Niobium Oxide) until amorphization; followed by a chemical dissolution in H2O at 90°C of amorphized precursors. The resulting solution was evaporated obtaining a dry and amorphous powder that was annealed at 850°C for 2 h in room atmosphere. The crystallization process from the amorphous state to the crystalline LiNbO3 was followed by thermal analysis. The amorphus and annealed powders were characterized by Raman spectroscopy, X-ray diffraction (XRD) and their morphology examined by high-resolution transmission electron microscopy (HRTEM). XRD and Raman confirmed that calcined powders are pure LiNbO3. 86 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ AMC-523 ] Optical and magnetic properties of LiNbO3:Fe Cesar D. Fierro Ruiz ([email protected]) 1 , Eva Maria Cabral Larquier 1 , Jose Trinidad Elizalde Galindo 1 , Jose Rurik Farias Mancilla 1 1 Departamento de Física y Matemáticas, Universidad Autónoma de Ciudad Juárez, Av. Charro 450 Nte. Col. Partido Romero CP 32310 Powders of LiNbO3:Fe were obtained by mechanosynthesis with different concentration of Fe2O3. The process was realize in two steps. First, was mechano-active the Li2CO3 and Nb2O5 in high energy ball milling to obtain LiNbO3. Then the powder was calcined whit a ramp of 1.4 C per minute until 850 C, and it remained in isotherm for 2 hours. Second, mixed the LiNbO3 obtained and Fe2O3 for 30 minutes in the high energy ball milling. Later, calcined for 60 hours to 850 C for diffuse Fe atoms into the structure. The powders was characterization for XRD, Raman spectroscopy, FT-IR spectroscopy and Vibration sample magnetometer. Diffraction pattern show that LiNbO3 structure remains with the doped, also, relative intensity of peaks related with [0 1 2] and [1 1 0] planes changes in function of doping concentration. FT-IR spectrums did not show significant changes in the vibrational mode related with Niobium and Oxygen octahedron. Raman spectrums present a change in the area under curve corresponded to the regions between 210-295 cm-1 and 500-700 cm-1, this vibrational modes are the lithium ions displacement and extension Nb-O, respectively. Absorption edge, exhibit a change in function to the concentration of dopant. Powders had a ferromagnetic behavior, and the magnetic moment net increases quadratically as a function of doping concentration. 87 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ AMC-525 ] Synthesis and characterization of polycaprolactone fibers with LiNbO3 nanoparticles Eva Maria Cabral Larquier ([email protected]) 2 , Simon Yobanny Reyes Lopez 1 , Cesar David Fierro Ruiz 2 , Jose Trinidad Elizalde Galindo 2 , Pierre Giovanni Mani Gonzalez 2 , Jose Rurik Farias Mancilla 2 1 Departamento de Ciencias Químico Biológicas, Universidad Autónoma de Ciudad Juárez, Av. Benjamin Franklin 4650 Zona PRONAF CP 32315 2 Departamento de Física y Matemáticas, Universidad Autónoma de Ciudad Juárez, Av. Charro 450 Nte. Col. Partido Romero CP 32310 The electrospinning technique is one of the most technique used for fabrication of nanofibers, these fibers are made from a conductor polymer, as polycaprolactone (PCL). The LiNbO3 nanoparticles are mixed with PCL to achieve dispersion of nanoparticles. Actually, there are no bibliography of fibers based on LiNbO3 nanoparticles embedded in PCL. For this reason we are developing a research, with a possible applications in the development of waveguide. The nanofibers structure and chemistry were characterized with x-ray diffraction (XRD), Raman and FT-IR spectroscopies, and SEM. 88 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ AMC-561 ] Structural effects on sandy soils by adding functionalized resins Delia Cristina Altamirano-Juárez ([email protected]) 3 , Pedro Montes-García 1 , Margarito Ortiz-Guzmán 1 , José Ernesto DomínguezHerrera 3 , Efraín Rubio-Rosas 2 1 Centro Interdisciplinario de Investigación para el Desarrollo Integral Regional, Unidad Oaxaca. Instituto Politécnico Nacional. Calle Hornos Núm. 1003. Col. Nochebuena, Santa Cruz Xoxocotlán, Oaxaca, México. C. P. 71230 2 Centro Universitario de Vinculación y Transferencia de Tecnología; Prolongación de la 24 Sur y Av. San Claudio, Ciudad Universitaria, Col. San Manuel, Puebla, Puebla, México. C. P. 72570 3 EP Nanotecnología, Universidad Tecnológica del Centro de Veracruz. Av. Universidad Núm. 350, Localidad Dos Caminos, Cuitláhuac, Veracruz, México. C. P. 94910 Novel composites were obtained from two types of soils with high silica content (> 60%) using as agglutinants different dosages of fatty acids and natural resins in both low and high density. Both, the variations in the signal of X-Ray diffraction patterns analyzed and changes observed by scanning electronic microscopy for the different relationships of the agglutinants, reveal that it is possible to induce the formation of compounds that it favors the mechanical resistance of adobe compacted blocks in absence of cementing admixtures. The low cost of production and the environmental benefit of not adding commercial cements allow recommending it as an appropriate material for the residential construction industry, which fulfills the corresponding standards. 89 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla BIOMATERIALS AND POLYMERS (BIO) Chairman: Roberto Olayo (UAM-IZTAPALAPA) Oral Session [Invited-Talk] Development of Hybrid Biomaterials to Be Implanted in Living Organisms to Fulfill Different Functions Rogelio Rodríguez Centro de Física Aplicada y Tecnología Avanzada Campus UNAM, Juriquilla Biomaterials of different types were designed in our lab to be implanted to fulfill different functions. Some of them were implanted for bone ingrowth in cases of traumatism; they have the morphology of real bone. Others were designed as bio-package to protect sensor devices that, once implanted, can provide valuable information of some conditions of the host; this allows detecting, prematurely, some illness conditions to be treated from the early stage, increasing the probability of success; in this case the morphology depends of the implantation place. Finally, other biomaterials were designed for controlled drug release; in this case the pore size should be small and the pore volume fraction as large as possible to storage the large amount possible of medicament; this device was specifically designed as biomarker to provide the position of the cancerous tumor and to release, in a controlled way the medicament near the position of the tumor; the selected medicament was cis-platinum. 90 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ BIO-68 ] A composite made with a metakaolin based geopolymer and rice husks in high proportions as an alternative to concrete and wood José de Jesús Pérez Bueno ([email protected]) 1 , Coraquetzali Magdaleno Lopez 1 1 Centro de Investigación y Desarrollo Tecnológico en Electroquímica, S.C. Parque Tecnológico Querétaro s/n Sanfandila, Pedro Escobedo, Qro., México. 76703. The alkaline activation of aluminosilicates is a technology called geopolymerization, which has no direct CO2 emissions. Geopolymers exhibit good physical porosity, at micro- and nano-scale, low shrinkage, high mechanical strength, good thermal stability, durability, surface hardness, chemical resistance and fire resistance. In this work, a geopolymer composite is presented based on metakaolin as a matrix with aggregates of agro-industrial waste in high ratio (with around 80-85% of rice husk – not carbonized). The geopolymeric matrix covered the rice husks, which were found attached to the matrix. The analysis of Confocal Laser Scanning Microscopy and SEM helped to identify husks distribution within the matrix without being observed segregation or even distribution of any component. The materials obtained had values similar to those of the concrete resistance, which are specifications searched in construction issues. Heat treating these materials become very lightweight, without incorporate a lightweight aggregate or a chemical foaming agent. Their strength properties did not change significantly when exposed to ambient or elevated temperatures. The heat treatment given to these materials allowed obtaining a porous structure and not soluble in water. The high rates of rice husk in these materials, with compressive strengths similar to concrete, particularly exceeded expectations and potentially become an alternative to concrete providing an option to solve their disposal problem. 91 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ BIO-73 ] Preparation of polyallylamine as a drug carrier for spinal cord lesions Maribel González-Torres 1 , Maribel González-Torres 4 , Ma. Guadalupe Olayo González ([email protected]) 2 , Guillermo J. Cruz Cruz 2 , Lidia Ma. Gómez Jiménez 2 , Lidia Ma. Gómez Jiménez 4 , Francisco González-Salgado 2 , Francisco González-Salgado 3 , Rodrigo Mondragón Lozano 2 1 Departamento de Física, Instituto Nacional de Investigaciones Nucleares, Carr. MéxicoToluca Km 36.5, Ocoyoacac, Edo. Mex., CP 52750, Mexico. 2 Departamento de Física, Instituto Nacional de Investigaciones Nucleares, Carr. MéxicoToluca Km 36.5, Ocoyoacac, Edo. Mex., CP 52750, México. 3 Departamento de Posgrado, Instituto Tecnológico de Toluca, Av. Tecnológico s/n, Col. La Virgen, Metepec, Edo. Mex., CP 52140, México. 4 Posgrado en Ciencia de Materiales, Facultad de Química, Universidad Autónoma del Estado de México, Paseo Tollocan y Colón, Toluca, Edo. Mex., CP 52000, México. Polyallylamine (PAl) synthesized by plasma was prepared as a drug carrier of dapsone to be used as an implant in the spinal cord after a severe injury. PAl has been studied in the central nervous system in areas with severe injuries to reduce secondary destruction of healthy tissue. Dapsone on its part has been used subcutaneously with the same objective. In this work they are prepared to be used together as implants directly in the lesion site. Once synthesized, PAl films were lyophilized with water in order to induce porosity and to separate light fractions. The dapsone uptake was done with different mass ratios: 1-1, 1-10, 1-100, by immersing the polymer in dapsone and ethanol solutions with the result that the drug adheres to the polymer forming non-homogeneous core shell structures. The release of dapsone from the polymer was performed in two different solutions: water, and Krebs Ringer, two different models were considered: dynamic and static simulating the similar conditions in the human fluids. The desorption was measured by UV-Vis spectroscopy. Morphology and chemical structures were studied before and after adding the drug. 92 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ BIO-75 ] Electromagnetic absorption and electric interaction in hybrid structures of titanium oxide and thiophene Francisco González-Salgado 1 , Francisco González-Salgado 2 , Guillermo J. Cruz Cruz ([email protected]) 1 , Ma. Guadalupe Olayo González 1 , Genoveva García Rosales 2 , Maribel González-Torres 1 , Maribel González-Torres 4 , Lidia Ma. Gómez Jiménez 1 , Lidia Ma. Gómez Jiménez 3 1 Departamento de Física, Instituto Nacional de Investigaciones Nucleares, Carr. MéxicoToluca Km 36.5, Ocoyoacac, Edo. Mex., CP 52750, México. 2 Departamento de Posgrado, Instituto Tecnológico de Toluca, Av. Tecnológico s/n, Col. La Virgen, Metepec, Edo. Mex., CP 52140, México. 3 Posgrado en Ciencia de Materiales, Facultad de Química, Universidad Autónoma del Estado de México, Paseo Tollocan y Colón, Toluca, Edo. Mex., CP 52000, México. 4 Posgrado en Ciencia de Materiales, Universidad Autónoma del Estado de México, Paseo Tollocan y Colón, Toluca, Edo. Mex., CP 52000, México. Organometallic hybrid structures of titanium oxide and thiophene (TiOx-Th) were synthesized by plasma with the objective to design a photo-collector capable to absorb electromagnetic energy in the visible solar irradiation interval. Titanium tetrapropoxide (TTP) and thiophene (Th) were used as precursors with a 1:1 mass ratio, which chemically reacted in a vacuum tubular glass chamber under rf resistive electrical glow discharges of water vapor plasmas. Films and particles were formed with diameter in the 220-470 nm interval, decreasing as the power of synthesis increased. The synthesized TiOx-Th compounds absorbed electromagnetic radiation in two regions, 270-370 and 370-850 nm, which could be related with the TiO and thiophene fractions respectively. The electrical conductivity increased as a function of temperature as a volumetric effect sensitive to incident beams on the surface. The activation energies of the electromagnetic absorption and the transference of charges was calculated between 0.11 and 7.4 eV and compared. The presence of particles on the surface is related with the absorption process and their capacity to transfer electrical charges. 93 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ BIO-116 ] Particle size effect on thermal and mechanical properties of PP filled with nano CaCO3 from eggshell. Diana Samantha Villarreal Lucio ([email protected]) 1 , José Luis Rivera Armenta 1 , Ana Luara Martínez Hernández 2 , Ivan Alziri Estrada Moreno 3 , Ulises Páramo García 1 , Ana María Mendoza Martínez 1 1 Departamento de Estudios de Posgrado e Investigación, Instituto Tecnológico de Cd. Madero, Juventino Rosas S/N, Los Mangos, 89440 Cd Madero, Tamps., 2 Departamento de Estudios de Posgrado e Investigación, Instituto Tecnológico de Querétaro, Av. Tecnologico S/N, Centro, 76000 Santiago De Queretaro, QRO 3 División de Ingeniería y Química de Materiales, Centro de Investigación de Materiales Avanzados, Ave. Miguel de Cervantes 120, Industrial Chihuahua, 31109 Chihuahua, CHIH Thermal and mechanical properties of a PP reinforced with three different particle sizes of CaCO3 from eggshell were evaluated. Nanoparticles were obtained using two mechanical attrition technics and an ultrasonic treatment: the eggshell was ground in a blender, the second grinding was made in ball mill and finally the particles were subjected to an ultrasonic treatment using three different sonication media. The particle size diminished in every step, obtaining nanosized particles during the ultrasonic treatment, using liquid media with different vapor pressures it is possible to get distinct nano-sizes. Compounding was carried out in a mixer chamber. The optimal PP-CaCO3 formulation according to particle size was investigated. Thermogravimetric behavior, dynamic mechanical analysis and morphology of resulted composites were analyzed. 94 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ BIO-129 ] Implantation of composite scaffold of pla-ha coated with polypyrrole for the generation of bone neotissue in rabbit: biological and mechanical evaluation. María Guadalupe Flores Sánchez ([email protected]) 1 , Roberto Olayo González 1 , Juan Morales Corona ([email protected]) 1 , Atlántida Raya Rivera 2 , Ricardo Esquiliano Rendón 2 , Raquel González Pérez 2 1 Departamento de Física, Área de Polímeros, Universidad Autónoma Metropolitana, Unidad Iztapalapa 2 Tissue Engineering Laboratory, Infantile Hospital of Mexico, Federico Gómez Bone tumors such as osteosarcoma are the seventh leading cause of cancer death in Mexico. Osteosarcoma originates in bone cells and occurs primarily in the metaphysis of long bones like the distal femur, the proximal end of the tibia and humerus. Osteosarcoma affects people between 2 and 60 years old and is more common in males. Generally, a graft or bone substitute to help repair a skeletal deficiency due to this type of disease is required. Tissue Engineering is an alternative to generate synthetic bone tissue, using the combination of biomaterials, cells and biological factors, in order to give the patient preservation in gait, functional recovery and mobilization. Biomaterials that can be used as bone substitutes should possess biocompatibility, biodegradability, and have to be osteoinductive, with proper mechanical properties. The combination of polymers with ceramic materials meets most of the properties of bone. In this work, the electrospinning technique was used to produce porous scaffolds of poly(lactic acid) (PLA) and hydroxyapatite (HA), which serve as support for the growth of bone cells, osteocytes. To induce cell adhesion and stimulation, a thin film of polypyrrole (PPy-I) doped with iodine is deposited by plasma polymerization on the scaffolds. The scaffold made of PLA-HA-PPy/I underwent in vivo cell culture in rabbits for 30 days. The newly formed tissue was characterized by scanning electron microscopy, histology studies and mechanical stress tests. 95 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ BIO-147 ] Plasma polimeized semiconductor polymers as cell growth materials Roberto Olayo ([email protected]) 1 , Nancy Cecilia Islas-Arteaga 3 , Juan Morales-Corona 1 , Odín Ramírez-Fernández 3 , Rafael GodinezFernández 2 1 Departamento de Física, Área de Polímeros, Universidad Autónoma Metropolitana, Unidad Iztapalapa. 2 Departamento de Ingeniería Eléctrica, Lab. de Ingeniería de Tejidos, Universidad Autónoma Metropolitana, Unidad Iztapalapa. 3 Posgrado en Ingeniería Biomedica, Universidad Autónoma Metropolitana, Unidad Iztapalapa. Polymers such as polyaniline, PAn, polypyrrole, PPy, the polyallylamine, PAlly, and polythiophene, PTh, may have semiconductor properties when are plasma polymerized and on the surface have functional groups as amines or sulfurs of the thiophene ring. This makes them suitable for testing in cell culture. Glass substrates coated with the four materials, PAn, PPy, PAlly, and PTh, were prepared Through the plasma polymerization technique, at powers of 15W, 30W and 50W and polymerization times of 15 min and 30 min. These materials were characterized by contact angle, SEM, FT-IR-ATR and Raman spectroscopy. Human hepatocyte cells, HepG2, were cultured on the substrates, with approximately 1x106 cells per material. The cell culture was followed for 11 days and photomicrographs of each sample were taken. The evolution of cell growth was followed in all materials (anchorage, reproduction and monolayer formation). 96 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ BIO-284 ] Surface characterization of titanium surfaces before and after exposition to an hydrogen peroxide ambient Abril Fonseca García ([email protected]) 3 , Abril Fonseca García 4 , Jonatan Peréz Alvaréz 3 , Mauro Giorcelli 1 , Argelia Almaguer Flores 2 , Sandra Elizabeth Rodil Posada ([email protected]) 3 1 Department of Applied Science and Technology, Politecnico di Torino, Corso Duca degli Abruzzi 24, Torino 10129, Italy. 2 División de estudios de posgrado e investigación, Facultad de Odontología, Universidad Nacional Autónoma de México, Circuito exterior s/n, Ciudad Universitaria, 04510 México D. F. Mexico. 3 Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Circuito Exterior s/n, CU, México D.F. 04510, Mexico 4 Posgrado en Ciencia e Ingeniería de Materiales, Universidad Nacional Autónoma de México. The most important property of materials used for fabricating implants is the biocompatibility, followed by corrosion resistance. In implantology and orthopedics, the metal more used is titanium (Ti) due to its excellent osseointegration properties which lead to a successful recovery and improvement in quality of life of patients. Nevertheless, from the fundamental point of view, it is not clear why Ti is the most suitable metal for biomedical applications. In this work, we studied the behavior of Ti surfaces in inflammatory environmental. For this aim, we created an environment rich of oxidizing species that simulate a body inflammatory response after the implantation of a foreign body. The response of the Ti surfaces is compared to medical grade stainless steel (AISI316L) and titanium oxide thin films deposited on Ti substrates. The films were deposited by magnetron sputtering using a pure Ti target and an argon-oxygen environment. The three materials; Ti, AISI316 and TiOx films, were immersed in a physiological solution (Hartman) with the addition of 50 mM of hydrogen peroxide to simulate the foreign body reaction environment. The surfaces were kept in immersion for 7 days, refreshing solution every 24 hours in order to keep the hydrogen peroxide in reactive conditions. The surfaces were characterized before and after 7 days of immersion by X ray diffraction, atomic force microscopy to study roughness and topography, X-ray photoelectron spectroscopy for studying the chemical composition, contact angle to evaluate the surface energy and finally, potentiometric titration to obtain the surface charge. Acknowledgements: To CONACyT for the PhD scholarship and economical support to both and PAPIIT-UNAM IN118814, IN118914, IG100113 grants. 97 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ BIO-454 ] Effects of cooling rate, morphological and structural propierties of BIO-HAP from bovine bone Cristian Felipe Ramirez Gutierrez 1 , Anderzon Felipe Palechor Ocampo 1 , Sandra Milena Londoño Restrepo 1 , Beatriz Millan Malo 1 , Mario Enrique Rodriguez Garcia ([email protected]) 1 1 Centro de Física Aplicada y Tecnología Avanzada, Universidad Nacional Autónoma de Mexico Campus Juriquilla, Qro., Mexico Hydroxyapatite (HAp) is a ceramic material with chemical formula: Ca10(PO4)6OH2. Hap is the major mineral component of the vertebrate bone and tooth. Other mineral phases present in the bone are calcium phosphate, dicalcium phosphate, tricalcium phosphate, and others. Further, Hap contains mineral traces, such as, Na, Mn, K, Li, Cr, Mg, Fe, and others, that are important in the bio-mineralization process. The effect of cooling rate after calcined on physicochemical properties of biohydroxyapatite (Bio-Hap) from bovine bone was studied in this investigation. Calcination process was carried out in furnace in air atmosphere to 900 °C at 5 °C/min. The samples studies were: HAP-CW (Hap cooled in water at room temperature), Hap-Fair (Hap cooled into the furnace), Hap-CAir (Hap cooled out furnace), and Hap-N2 (Hap cooled in liquid nitrogen). The samples were characterized thermally by thermogravimetrical analysis (TGA), morphologically by scanning electron microscopy (SEM), and structurally by X-ray diffraction (XRD). The results indicate that low cooling rate for Hap cooled into the furnace produce single crystals with high crystalline quality. Keywords: Bio-hydroxyapatite, cooling rates, crystalline quality. Giraldo-Betancur AL, Espinoza-Arbelaez DG, del Real-Lopez A, Millan-Malo BM, Rivera-Muñoz E, Gutiérrez-Cortez E, Pineda-Gomez P, Jimenez-Sandoval SJ, Rodriguez-Garcia ME. Comparison of physicochemical properties of bio and commercial hydroxyapatite. Curr Appl Phys 2013; 13:1383–1390. 2. Krishna SR, Chaitanya CK, Seshadri SK, Kumar TSS. Fluorinated hydroxyapatite by hydrolysis under microwave irradiation. Trends Bio-matter Artif Organs 2002; 16:15–17. 3. Bahrololoom ME, Javidi M, Javadpour S, Ma J. Characterization of natural hydroxyapatite extracted from bovine cortical bone ash. J Ceram Process Res 2009; 10:129–138. 1. 98 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ BIO-502 ] Growth of silver particles with different morphology on hydroxyapatite Yosemik Arjuna León Nataret 2 , Aarón Israel Díaz cano 2 , Efraín Rubio Rosas 1 , Edith Bravo González ([email protected]) 2 1 2 Benemérita Universidad Autónoma de Puebla, San Manuel, 72570, México Instituto Politécnico Nacional, UPIITA, Gustavo A. Madero, 07340, México The synthetic hydroxyapatite (HA) has a similar mineral phase with the bone and with excellent characteristics of biocompatibility and osseointegration in a biological medium. Although exist problems in connection with bacterial infections when these implants are inserted into the human body; One antibacterial agent proposed is the silver and his alloys, these has been studied extensively, showing that had antibacterial effects through interaction of proteins and enzymes of the bacteria causing structural damage in to the cell wall and in the membrane, the investigations show that at low concentrations of silver is not toxic to mammals, but in high concentrations cans cause argyria and cytotoxicity. In this paper was determined the influence of the growth of silver nanostructures on the surface of structures of bovine hydroxyapatite with different morphology. The silver particles were obtained by chemical reduction, taking as precursors Silver Nitrate (AgNO3), Sodium Citrate (Na3C6H5O7) and ammonium hydroxide (NH4OH). The characterization was performed by scanning electron microscope (SEM), X-ray diffraction (XRD) and Atomic Force Microscope (AFM). The results showed that the bone lamellae are an important factor on the growth and morphology of silver nanoparticles, even when the chemical composition of the substrate is the same. One sample observed by scanning electron microscope showed the growth of nanostructures on the surface of the bone lamellae, also shows that in the surface of this bone has smaller structures with low dimensions in nanometric scale. When it used high concentrations, the silver particles grow up into lamellae boundaries as nucleation centers. 99 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ BIO-539 ] Osteogenic Differentiation of Human Mesenchymal Stem Cells by Porous Bovine Bone Matrix Nayeli Rodríguez Fuentes ([email protected]) 2 , Luz E Alcántara Quintana 1 , Javier R Ambrosio Hernández 3 , Cristina Piña Barba 2 1 Aplicaciones en Terapia Celular, S. A. de C. V., Santa Barbara. Col. Jardines de Santa Rosa. Puebla, México 2 Departamento de Materiales Metálicos y Cerámicos, Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México. Mexico City 04510, Mexico 3 Departamento de Microbiología y Parasitología, Facultad de Medicina-UNAM, Mexico City 04510, Mexico The differentiation of mesenchymal stem cells (MSCs) in vitro, is a processes that depends on the culture conditions. Soluble compounds such as grow factors and numerous reagents, result in a chondrogenic, adipogenic, neurogenic or osteogenic differentiation. Osteogenic differentiation of MSCs in vitro is induced by the presence of dexamethasone, ascorbic acid and β-glycerol phosphate, however, the role of the insoluble compounds such as the biomaterials in regulating the osteogenic differentiation of MSCs are unclear. In this study we delineate the role of the porous bovine bone matrix (NKB) in the osteogenic induction of MSCs in an in vitro model, through the measurement of expression of the gene key markers in the osteogenic differentiation such as transcriptional factor CBFA-1 and Osteocalcin. The results shown that NKB has osteoinductive properties in MSCs cultures, because induce the activation of CBFA-1 and Osteocalcin, without the addition of the soluble inductors. In addition, the NKB promote cell adhesion and proliferation similarly to the positive control, which is a culture of MSCs without NKB but with osteoblastic inductors as ascorbic acid, Bglycerophosphate and dexamethasone. This osteoinductive property of NKB, as well as its full characterization might favour its best use in regenerative medicine. Acknowledgements. The authors acknowledges to DGAPA/UNAM for financial support received as a postdoctoral grant and would like to thank the PAPIIT program for the financial support through the IG100114 project, CONACyT through project 214128. Also to thank the DGAPA IN201510 and DGAPA IXTLI IX200610. 100 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ BIO-554 ] CHEMICAL DERIVATIZATION OF PLASMA POLYMER FILMS FOR QUANTIFICATION OF AMINE, HYDROXYL AND CARBOXYL GROUPS BY HR-XPS Juan-Carlos Ruiz-Bucio ([email protected]) 1 1 División de Ciencias Básicas e Ingeniería, Universidad Autónoma Metropolitana Iztapalapa, Av. San Rafael Atlixco No. 186, 09340 Mexico City, Mexico Plasma-assisted modification- and deposition-processes have been used for creating bioactive polymer surfaces in biomedical and cell-culture applications. Plasma-polymerized Allylamine (pp-AA) or Nitrogen (N)-rich organic thin-deposits are particularly advantageous because N-containing functional groups, specifically primary amines (-NH2), can readily be incorporated [1, 2]. Oxygen-rich plasma films obtained with different precursors, e.g. gas mixtures of oxygen-ethylene or acrylic acid and allylalcohol monomers, are of interest as a biomaterial as well [3]. It is not possible to quantify –NHx and –OH groups in a polymer containing both functionalities when chemical derivatization (CD) with survey-XPS or high resolution X-ray photoelectron spectroscopy (HR-XPS) are performed, but together with CD reactions and HR-XPS. The use of CD and HR-XPS for labeling of the desire functional groups is a powerful tool for quantification of -NHx, -OH and COOH groups, among others [3,4]. The present work describes the use of different derivatization reactions for quantification of -NHx, -OH and COOH groups present in different plasma polymer films deposited by a PECVD method. XPS spectra, before and after derivatization, will be present for discussing their chemical characterization. References: 1. R. Förch, A. N. Chifen, A. Bousquet, H. L. Khor, M. Jungblut, L.-Q. Chu, Z. Zhang, I. Osey-Mensah, E.-K. Sinner, W. Knoll (2007); Chem. Vap. Deposit. 13, 280. 2. J. C. Ruiz, A. St-Georges-Robillard, C. Thérésy, S. Lerouge, M. R. Wertheimer (2010); Plasma Process. Polym. 7, 737. 3. J.-C. Ruiz, P.-L. Girard-Lauriault, M. R. Wertheimer (2015); Plasma Process. Polym. 12, 225. 4. J.-C. Ruiz, S. Taheri, A. Michelmore, D. E. Robinson, R. D. Short, K. Vasilev, R. Förch (2014); Plasma Process. Polym. 11, 888. 101 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ BIO-559 ] Analysis of the biocidal efficacy of Neem oil embedded in nanostructured reservoirs of Titanium Oxide Héctor de Jesús Andrade-Tomas ([email protected]) 2 , Delia Cristina Altamirano-Juárez ([email protected]) 2 , Octavio Maldonado-Saavedra 2 , Efraín Rubio Rosas 1 , Juan Manuel Padilla-Flores 2 1 Centro Universitario de Vinculación y Transferencia de Tecnología; Prolongación de la 24 Sur y Av. San Claudio, Ciudad Universitaria, Col. San Manuel, Puebla, Puebla, México. C. P. 72570 2 PE Nanotecnología, Universidad Tecnológica del Centro de Veracruz. Av. Universidad Núm 350; Localidad Dos Caminos. Cuitláhuac, Veracruz, México. C. P. 94910 In recent years there has been increased the interest in the use of natural extracts as an alternative to the control of microorganisms pathogenic in humans. Neem oil has become important because its active ingredient Azadirachta indica is associated with beneficial effects against infectious diseases. Microparticles of Neem oil were impregnated following a hydrothermal route, over wafers of Titania elaborated from powders previously synthesized by the Sol-Gel Technique. The concentration and degree of diffusion of Neem oil on the surface of the tablets were evaluated using optical and scanning microscopies; two lots of impregnated tablets were randomly selected to develop bacterial cultures of Escherichia Coli both in the surface as immersed in the composite powder of Neem/TiO2. It was observed that the effectiveness of Neem oil was greatest with powdered samples, therefore it is proposed that the intensity of the bactericidal reactivity of Neem oil microparticles is influenced by the increase surface porosity of Titanium Oxide. 102 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla Sesión Poster [ BIO-6 ] Surface roughness and hardness evaluation of some base metal alloys and denture base acrylics used for oral rehabilitation Gabriela Cortés Sandoval ([email protected]) 2 , Juan Pablo Loyola Rodríguez 4 , Rita Elizabeth Martínez Martínez 4 , Pánfilo Raymundo Martínez Rodríguez 3 , Vladimir Alonso Escobar Barrios 1 1 División de Materiales Avanzados, Instituto Potosino de Investigación Científica y Tecnológica, A.C., Camino a la Presa San José # 2055, Lomas 4a. sección, CP 78210, San Luis Potosí, SLP, México 2 Doctorado Institucional en Ingeniería y Ciencia de Materiales, Universidad Autónoma de San Luis Potosí, Av. Dr. Manuel Nava # 6, Zona Universitaria, CP 78290 San Luis Potosi, SLP, México 3 Instituto Tecnológico Superior de Irapuato, carretera Irapuato-Silao km 12.5, Irapuato, Guanajuato, México 4 Master Degree in Advanced Education in General Dentistry, San Luis Potosi University, Av. Dr. Manuel Nava # 2, Zona Universitaria, CP 78290 San Luis Potosi, SLP, México Dental materials for clinical use are considered medical devices that have to meet stringent safety and efficacy requirements. The aim of this study was to evaluate and compare, basal and after polishing, surface roughness, topography, and hardness of some dentures base materials and base metal alloys used in oral rehabilitation by using atomic force microscopy (AFM), scanning electron microscopy (SEM), and Vickers hardness test (VHN), respectively. For each study group, 10 cylindrical specimens measuring 3 mm in diameter and 20 mm thick were prepared following the manufacturer's instructions. All specimens were subjected to basal measurements for subsequent comparisons and then samples were polished by the standard polishing procedure for each material used. To determine the difference between the variables before and after polishing, the Student t test (dependent samples) was used. The comparison between the study groups was performed using ANOVA one-way and Tukey–Kramer test. Significant differences between basal roughness values and after a polishing process were observed. Mainly there appears to be a relationship between the content of the material that confers the hardness and the surface roughness values. The SEM analysis showed significant changes in surface topography of base metal alloys. Thermosetting acrylic presented the lowest roughness value before (93 nm) and after (48 nm) polishing technique, and apparently did not show any visual surface topography change. 103 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ BIO-10 ] Comparison of physical and mechanical properties of three base metal alloys used in restorative dentistry. Gabriela Cortés Sandoval ([email protected]) 2 , Juan Pablo Loyola Rodríguez 3 , Rita Elizabeth Martínez Martínez 3 , Vladimir Alonso Escobar Barrios 1 1 División de Materiales Avanzados, Instituto Potosino de Investigación Científica y Tecnológica, A.C., Camino a la Presa San José # 2055, Lomas 4a. sección, CP 78210, San Luis Potosí, SLP, México 2 Doctorado Institucional en Ingeniería y Ciencia de Materiales, Universidad Autónoma de San Luis Potosí, Av. Dr. Manuel Nava # 6, Zona Universitaria, CP 78290 San Luis Potosi, SLP, México 3 Master Degree in Advanced Education in General Dentistry, San Luis Potosi University, Av. Dr. Manuel Nava # 2, Zona Universitaria, CP 78290, San Luis Potosi, SLP, México The purpose of the present study was to evaluate and compare some physical and mechanical properties of three base metal alloys commonly used in oral rehabilitation: cobalt-chromium (R-800®), nickel-chromium (Verabond®) and copper-aluminum (NPG®). Tests were performed in accordance with the ADA specification no. 14 for dental base casting alloys. Thirty specimens of 40 mm in length and 3 mm diameter were prepared according to the manufacturer’s instructions. The following characteristics were analyzed: flexural strength, flexural modulus, fracture toughness, surface hardness and surface roughness. The mechanical properties were performed using a three-point bending test on a universal testing machine. The span distance between two supports was 32 mm and the crosshead speed during the test was 20 mm/min. Vickers harness test was performed using a microhardness tester with an applied load of 9.8N at 10 seconds dwell time; three Vickers indentations were conducted for each specimen and standard deviation was recorded. All roughness measurements were obtained by atomic force microscopy in contact mode calibrated to 49.5 mm2 sample surface; three measurements were performed for each specimen and the average for Ra values was used for the statistical analysis. The mean and standard deviation are reported. After analyzing the obtained results important features were observed. The alloys containing copper-aluminum exhibited the lower mechanical properties compared to alloys containing chromium. In the case of physical properties, it appears to be a relationship between the content of material that confers the hardness and the surface roughness values. 104 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ BIO-23 ] multiscale polymer composites for aircraft industry, based on functionalized carbon nanotubes: processing and characterization Juan Manuel Hernandez Andrade 1,2 , Carlos Rubio Gonzalez 1 , Carlos Velasco Santos ([email protected]) 2 1 Centro de Ingeniería y Desarrollo Industrial (CIDESI), Av. Playa Pie de la Cuesta No. 702. Desarrollo San Pablo, C.P. 76130, Santiago de Querétaro, Querétaro, México. 2 División de Estudios de Posgrado e Investigación, Maestría en Ingeniería, Instituto Tecnológico de Querétaro, Av. Tecnológico s/n esq. Gral. Mariano Escobedo, Col. Centro Histórico, C.P. 76000, Santiago de Querétaro, Querétaro, México. The use of carbon fiber- reinforced polymers (CFRP) in the aircrafts and automobile industry is well known, these materials possess excellent mechanical properties of high strength and stiffness, in addition to low density in comparison to the metals which lightens the final weight. However, the weakness of these materials is related with the zones where the resin prevails over carbon fiber and the fracture can be propagated there. On the other hand, in the last decade, carbon nanotubes (CNTs) have shown be excellent reinforcement to polymer matrices to develop polymer nanocomposites. Thus, it has been proposed recently, the combination of carbon fiber (micro level) and nanomaterials to processing multiscale composites in order to take advantage of both levels (micro and nano). Therefore, in this research are processed laminated CFRP, these are modified with CNTs to improve the mechanical properties of the final component. Functionalization of CNTs achieved in a microwave generates chemical groups that are useful in the dispersion of the polymer matrix and then in the properties of multiscale composites. Functionalized and unfunctionalized CNTs were dispersed using an epoxy resin between prepreg plies of CFRP and cured in autoclave. Different concentrations (0.1 wt%, 0.3 wt%, and 0.5 wt%) of CNTs were added in epoxy resin matrix. The composite materials were characterized by Dynamical Mechanical Analysis (DMA), tension, flexion and compression tests to evaluate thermal and mechanical properties. The resin employed to disperse nanomaterials presents lower thermal properties and softens the composites. However, it is observed that resin improves dispersion of nanomaterials. Also, the functionalization is useful to improve the mechanical properties in some concentrations. Hence, multiscale polymer composites using functionalized nanotubes could be contributing to diminish the low-impact fracture and improve the thermomechanical properties when a correct resin is used to disperse nanomaterials. 105 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ BIO-74 ] Using plasma to improve adhesion of polyallylamine coatings on metallic implants for the circulatory system Lidia Ma. Gómez Jiménez 1 , Lidia Ma. Gómez Jiménez 3 , Guillermo J. Cruz Cruz ([email protected]) 1 , Ma. Guadalupe Olayo González 1 , Maribel González-Torres 1 , Maribel González-Torres 3 , Francisco González-Salgado 1 , Francisco González-Salgado 2 , Rodrigo Mondragón Lozano 1 1 Departamento de Física, Instituto Nacional de Investigaciones Nucleares, Carr. MéxicoToluca Km 36.5, Ocoyoacac, Edo. Mex., CP 52750, México. 2 Departamento de Posgrado, Instituto Tecnológico de Toluca, Av. Tecnológico s/n, Col. La Virgen, Metepec, Edo. Mex., CP 52140, México. 3 Posgrado en Ciencia de Materiales, Facultad de Química, Universidad Autónoma del Estado de México, Paseo Tollocan y Colón, Toluca, Edo. Mex., CP 52000, México. One major causes of death in the population is the decrease of blood flow in the circulatory system caused by blockage of veins and arteries. An alternative to solve this problem is the implantation of a metallic mesh in the obstructed section to enlarge the diameter of the obstructed duct to partially restore the blood circulation. However, most metallic surfaces cause rejection reactions of different magnitude in the circulatory system which generate clots and obstructions again. Trying to avoid the post-implant reobstruction, the metallic devices have been coated with compatible biomaterials strong enough to resist the forces of the blood flow. In this area, this work presents a study of polyallylamine (PAl) coatings synthesized by plasma on nitinol and stainless steel substrates capable to resist the blood flow forces in Phosphate-Buffered Saline solutions (PBS) similar to the blood. Erosion, oxidation and sensitization with Argon and hydrogen peroxide plasmas were used on the metallic surfaces before and during the synthesis of the polymers. To simulate the conditions of the blood pumping and the heart's chamber contractions, the coatings were placed in tubes at a solution rate of approximately 66.5 cm/s at 37°C. The results showed that the coatings resisted up to two months without apparent degradation. SEM, XPS and contact angle analyses were used to follow the process. 106 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ BIO-80 ] Structural Characterization of Protein Microsensors Array by Mean of Optical Profilometry and AFM Claudia Mendoza-Barrera 1 , Victor Altuzar ([email protected]) 1 , Miguel A. Meléndez-Lira 2 , Julio C. Tinoco-Magaña 1 , Severino MuñozAguirre 3 1 Centro de Investigación en Micro y Nanotecnología, Universidad Veracruzana 2 Departamento de Física, CINVESTAV-IPN 3 Facultad de Ciencias Físico-Matemáticas, BUAP A microarray is a matrix containing from hundreds to thousands of microscopic sensory elements or spots printed on a flat functionalized surface which allows a specific interaction of multiple biomolecules including proteins. Some examples of reading this technology include the surface plasmon resonance and variable wavelength scanners used to determine the superficial density of biomolecules interacting with the microsensors. Nevertheless, none of these techniques provides the information relative to the structure of the interaction of the microsites fabricated for the biosensing. As a result, in this work we propose the combined use of the Atomic Force Microscopy (AFM) and optical profilometry to determine the structure and density of the interaction of microsite lines of bovine serum albumin (0.1, 0.5, 0.75 and 1.0 mg/ml) fabricated on the previously functionalized gold/glass substrate. For this purpose, we utilized solutions of bovine serum albumin (1.0 mg/ml) as the analytes during the protein-protein interaction. The negative control microsites corresponded to a line of white solutions of fibrinogen of human serum (1.0 mg/ml) which proved that the surface density (molecules/area) of the not-washed BSA spots is correlated to their thicknesses: 957.9 nm (1.0 mg/ml), 636.6 nm (0.75 mg/ml), 639.7 nm (0.5 mg/ml), and 490.4 nm (0.1 nm), whereas after the interaction with anti-BSA (1.0 mg/ml) they corresponded to 508.6, 218.0, 170.7, and 130.8 nm, respectively. In this way we proved that, before and after the protein interaction, the average spot roughness decreased with the concentration of the protein used for the fabrication of microsensors. 107 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ BIO-86 ] Synthesis and toxicity of Europium-doped nanohydroxyapatite for biomedical applications Paulina Guadalupe Miranda Meléndez ([email protected]) 1 , Gabriel Alejandro Martínez Castañón 2 , Nuria Patiño Marín 2 , Nereyda Niño Martínez 1 , Norma Verónica Zavala Alonso 2 , Facundo Ruiz 1 1 Doctorado Institucional en Ingeniería y Ciencia de Materiales 2 Doctorado en Ciencias Odontológicas In this study europium- doped nanohydroxyapatite was synthetized using a simple aqueous precipitation method. Calcium nitrate tetrahydrate, Ammonium dihiydrogenphosphate and Europium nitrate, were used, respectively, as Ca, P and Eu precursors with a Ca:P ratio 1.67. The nanohydroxyapatite was doped with 3, 5, 10 and 20 wt% of europium. Powders obtained were studied after they were dried at 70°C and hydrothermal treated at 120°c by 2 hours. The samples were analyzed by (Transmission Electron Microscopy) TEM, (X-ray diffraction) XRD, (Fourier transform infrared spectroscopy) and FT-IR, (Photoluminiscence) PL. The Eu concentration toxicity effects of nano Eu:HAP were studied on human fibroblasts cells in vitro. The sizes of the crystallites were about 10-70 nm with irregular morphology and present the (P63/m space group) phase corresponding to the JCPDS card 9-0432.The Eu-doped samples present photoluminescence lines at 590, 615, and 699 nm. The results of the toxicity experiments indicated that the powders were biocompatible and would not cause toxic reactions. This work provides an interesting view of the role of nanohydroxyapatite as ideal biomedical materials in future biomedical applications. Keywords: nanohydroxyapatite, synthesis, toxicity. References: Carmen Steluta Ciobanu, S. L. (2012). Synthesis, Structure, and Luminescent Properties of Europium- Doped Hydroxyapatite Nanocrystalline Powders. Journal of Nanomaterials, 1-9. Sangeeta Dey, Mitus Das, Vamsi Krishna Balla (2014). Effect of hydroxyapatite particle size, morphology and crystallinity on proliferation of colon cancer HCT116 cells. Materials Science and Engineering C336-339 Presenting author’s email: [email protected] 108 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ BIO-101 ] Determination of Lead Ions Removed from a Flowing Electrolyte in Presence of a Magnetic Field Using Raman Spectroscopy Rogelio Rodriguez Talavera ([email protected]) 1 , Maykel González Torres 1 , Susana Vargas Muñoz 1 , Blanca Huerta 2 , Guadalupe Méndez 2 1 Centro de Física Aplicada y Tecnología Avanzada. Universidad Nacional Autónoma de México. 2 Centro de Investigación en Química Aplicada Purpose: The removal of lead ions in a flowing electrolyte is a difficult problem, mainly because the ions distribute homogeneously in the fluid due to their mutual electrical repulsion. In this work is reported a new and non-invasive method to remove efficiently metal ions in aqueous solution flowing in a tubing, using a magnetic field to deflect the ions trajectories and concentrate these in one side of a specially designed cell; once the ions are concentrated, they can be removed. This technique could be used to remove toxic ions in the interior of arteries and veins in patients intoxicated by the ingestion of these metal ions. Method: Raman spectroscopy was used to prompt determination of removed metal ions. The presence of a magnetic field in an aqueous electrolyte flowing in a rectangular cell, allows an increment in the ions concentration due to the deflection effect of the ions trajectory. Results: It is possible to increase, in a region of the cell, the ions concentration in more than 80% respect to the average concentration; the removed ions are taken from this region. This is a rapid, efficient and non-invasive method for the removal of ions in aqueous solution. Raman spectroscopy was found to be a suitable technique to determine the amount of removed ions. Conclusion: The results indicated that it is possible to increase the ions concentration more than 80% in a region where it is possible to remove them. The increment in ions concentration produced by the deflection due to the magnetic field, together with the use of Raman spectroscopy, allows a rapid analysis of the removed ions without any previous preparation, suggesting that is a useful method for metal ions separation of interest to medical physicists. 109 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ BIO-103 ] Surface modification of poly (3hydroxybutyrate-co-3-hydroxyvalerate) by direct plasma- radiation-induced graft polymerization of hydroxyethyl-acrylamide Maykel González Torres 2 , Rogelio Rodríguez Talavera 2 , Susana Vargas Muñoz 2 , Alicia del Real López 2 , Gabriel López Calzada 2 , Efrain Rubio Rosas 1 , Eric Reyes Cervantes 1 1 Benemérita Universidad Autónoma de Puebla, Prolongación de la 24 Sur y Ave San Claudio. Ciudad Universitaria, Col San Manuel, C.P 72570, Puebla, Pue, México. 2 Centro de Física Aplicada y Tecnología Avanzada. Universidad Nacional Autónoma de México. Campus Juriquilla, Boulevard Juriquilla 3001, Santiago de Querétaro, Querétaro, C.P 76230, México A new type of cell-carrier-scaffold based on the surface modification of poly(3hydroxybutyrate-co-3-hydroxyvalerate) by direct plasma- radiation-induced graft polymerization of N-hydroxyethyl-acrylamide was prepared. Parameters as: membrane position for plasma treatment, delivering power and exposure time were varied. The yields over the films surface, the chemical changes, the morphology and roughness, were surveyed. The results indicate that the tailoring is more favourable at 10 W for 10 minutes because at lower values, low degrees of grafting are obtained, and at higher values, there is an increment of the film degradation. It was found that the use of 30% v/v of HEAA/ethanol (etching agent) leads to the formation of a coral like structure with greater average roughness than the pristine biomaterial. The modified surface slightly increased their hydrophilicity. . 110 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ BIO-127 ] Effects in clinical chemistry and hematology of rats exposed to silver nanoparticles using intraperitoneal administration Diana Peralta Álvarez ([email protected]) 5 , León Francisco Espinosa Cristóbal ([email protected]) 2 , Gabriel Alejandro Martínez Castañón 4 , Maribel Cervantes Flores 3 , Alejandro Donohue Cornejo 1 1 Departamento de Estomatología, Instituto de Ciencias Biomédicas, Universidad Autónoma de Ciudad Juárez 2 Departamento de Estomatología, Instituto de Ciencias Biomédicas, Universidad Autónoma de Ciudad Juárez. 3 Facultad de Ciencias Químicas, Universidad Juárez del Estado de Durango. 4 Laboratorio de Nanobiomateriales, Facultad de Estomatología, Universidad Autónoma de San Luis Potosí 5 Maestría en Ciencias Estomatológicas, Facultad de Odontología, Universidad Juárez del Estado de Durango. The bacterial effect of silver nanoparticles (SNP) has allowed their application in several areas, including the biomedical field; very few studies in the nowadays has evaluated the toxic effect of this nanomaterials using intraperitoneal way in vivo. This study evaluated clinical chemistry and hematology test in Wistar rats exposed al SNP by intraperitoneal way. Were prepared and characterized two sizes of SNP using dynamic light scattering (DLS) and transmission electron microscopy (TEM). Three concentrations of SNP were administrated intraperitoneal way (133.75µg/ml, 535µg/ml, 1070µg/ml) in periods of 96 hours to females Wistar rats for 30 days. Blood samples were collected before of SNP administration (0 days), in the middle of study (15 days) and in the end of exposition (30 days) for clinical chemistry and hematology evaluation. The size, distribution end shape of SNP (7.1 nm and 17.5 nm) was evaluated by DLS and TEM. The clinical chemistry values showed differences in urea nitrogen, uric acid, creatinine and triglycerides in the different sizes of SNP; in hematology monocytes and neutrophils values were found increased in both sizes of SNP used. The alterations found suggest a toxic effect of SNP administrated intraperitoneal way at Wistar rats causing kidney functions and inflammatory responses which can be related with size, shape, concentration and administration way used. 111 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ BIO-128 ] Biocompatible scaffolds based in polyhydroxybutyrate for tissue engineering applications. Emma Cortés Ortiz 2 , Maykel González Torres 1 , Susana Vargas Muñoz 1 , Roberto Olayo-Valles 2 , Juan Morales-Corona ([email protected]) 2 , Rogelio Rodriguez Talavera 1 , Roberto Olayo 2 1 Centro de Física Aplicada y Tecnología Avanzada. Universidad Nacional Autónoma de México. Campus Juriquilla 2 Departamento de Física, Área de Polímeros, Universidad Autónoma Metropolitana, Unidad Iztapalapa An ideal scaffold for tissue engineering must allow for three-dimensional cell culture, have high porosity, and must be biocompatible and biodegradable. The decomposition products should not be toxic to the host, should act as a temporary substitute for the extracellular matrix, and must provide a suitable chemical environment for the proper development of the cells. In this work, the preparation of a scaffold from polyhidroxybutyrate (PHB) is presented. This material is biodegradable and its degradation products can be metabolized by the host through enzymatic processes. PHB polymeric scaffolds were obtained by the electrospinning technique. The scaffolds were characterized by ATR-infrared spectroscopy, small angle X-ray scattering at, confocal Raman-microscopy, differential scanning calorimetry and scanning electron microscopy. 112 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ BIO-131 ] Scaffolds produced by electrospinning and modified by plasma for the regeneration of articular cartilage tissue. Nancy Cecilia Islas-Arteaga ([email protected]) 3 , Xinah Herón Gutiérrez García 3 , Atlántida Raya Rivera 2 , Juan Morales-Corona ([email protected]) 1 , Roberto Olayo 1 1 Departamento de Física, Universidad Autónoma Metropolitana, Unidad Iztapalapa 2 Hospital Infantil de México Federico Gómez, Depto. de Urología, Laboratorio de Ingeniería de tejidos 3 Posgrado Ingeniería Biomédica, Universidad Autónoma Metropolitana, Unidad Iztapalapa In this work scaffolds for tissue engineering were generated by electrospinning poly(lactic acid) (PLA) and polycaprolactone (PCL). The surface of the scaffolds was modified with polypyrrole-iodine (PPy-I) by plasma polymerization. The scaffolds were tested for treatment of chondral generation, showing encouraging results in in vitro cell growth experiments. The results were evaluated by scanning electron microscopy (SEM) showing that the pore size and pore size distribution are suitable for tissue engineering. To improve oxygen diffusion in the scaffolds, aggrecan (AG), an important component of the extracellular matrix of native cartilage, was added. The incorporation of AG in the scaffolds was confirmed by attenuated total reflectance FT-IR and SEM; SEM images show small crystals on the surface of the scaffolds which we attribute to the sugar content of AG. The scaffolds with AG were tested both in in vitro cultures and in vivo. The results show cellular growth and excellent biocompatibility. The mechanical properties of the scaffolds were measured by tensile tests and the results show promising characteristics for treatment of chondral defects or injuries. 113 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ BIO-132 ] Comparison study between two pyrrole polymers synthesized by plasma for biomedical applications Omar Fabela-Sánchez ([email protected]) 6 , L. Medina-Torres 2 , S. Sánchez-Torres 6 , H. Salgado–Ceballos 5 , Axayacatl Morales Guadarrama 1 , Laura Álvarez 6 , Rodrigo Mondragón 6 , Guadalupe Olayo-Gonzalez 4 , Guillermo Cruz-Cruz 4 , Araceli Díaz–Ruiz 3 , Camilo Rios-Castañeda 3 , Juan Morales-Corona ([email protected]) 6 , Roberto Olayo 6 1 Centro Nacional de Investigación en Imagenología e Instrumentación Médica, Universidad Autónoma Metropolitana 2 Depto. Ingeniería Química, Universidad Nacional Autónoma de México 3 Depto. Neuroquímica, Instituto Nacional de Neurología y Neurocirugía Manuel Velazco Suárez S.S.A. 4 Depto. Síntesis y Caracterización, Instituto Nacional en Investigaciones Nucleares 5 Unidad de Investigación Médica en Enfermedades Neurológicas, Hospital de Especialidades, Centro Médico Nacional Siglo XXI 6 Universidad Autónoma Metropolitana, Unidad Iztapalapa A biomaterial is a material designed to interact with tissues and fluid components of a host organism. The surface characteristics of biomaterials are key to establish optimal interactions and to avoid rejection. Our research group has synthesized plasma-polymerized pyrrole doped with iodine (PPy-I); which has shown excellent results of biocompatibility in in vitro and in vivo tests. In this work, we vary the conditions for PPy-I synthesis and analyze the resulting materials measuring contact angle, XPS, SEM, TEM and the rheological behavior of a suspension of the materials in bovine albumin. The results of this characterization are discussed with the perspective of the possible use of the materials as implants. 114 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ BIO-134 ] Scaffolds for artificial skin Graciela Ruiz-Velazco ([email protected]) 2 , Francisco MartínezFlores 1 , Juan Morales-Corona ([email protected]) 2 , Roberto Olayo 2 1 2 Banco de Tejidos y Piel, CENIAQ-Instituto Nacional de Rehabilitación Departamento de Física, Universidad Autónoma Metropolitana, Unidad Iztapalapa Skin injuries may be repaired by treatments that require skin grafts and strict medical care. The development of these treatments has created a high demand for healthy skin to be grafted onto the lesions; there is, however, a very limited availability. Tissue engineering is an alternative that may solve this problem; the combination of polymeric biomaterials and cell cultures that develop skin-like tissue may be used to heal or help recover a damaged area. This work presents the development of poly(lactic acid) scaffolds coated with plasma-polymerized pyrrole doped in situ with iodine. The scaffolds were characterized by a variety of techniques. Biological characterization was made by cell cultures of keratinocytes and human fibroblasts derived from skin. 115 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ BIO-135 ] Biodegradable scaffolds used in endothelial cell culture Mario Ramirez-Baez ([email protected]) 3 , Rafael GodínezFernandez 2 , Juan Morales-Corona ([email protected]) 1 , Roberto Olayo 1 1 Departamento de Física, Universidad Autónoma Metropolitana Departamento de Ingeniería Eléctrica, Universidad Autónoma Metropolitan 3 Posgrado en Ingeniería Biomedica, Universidad Autónoma Metropolitana, Unidad Iztapalapa 2 Aliphatic polyesters such as poly(lactic acid) (PLA) and polycaprolactone (PCL) are used for their biocompatibility and ease of processing in the development of tissue engineering scaffolds. In this work, these biopolymers were electrospun with a device that allows for injection in coaxial configuration. Using this configuration we prepared scaffolds of fibers of PCL and PLA with 50/50 composition. The scaffolds were characterized by scanning electron microscopy, thermogravimetric analysis, differential scanning calorimetry, X-ray diffraction, and confocal-raman microscopy. The scaffolds were also used for growing endothelial cells in a bioreactor. [ BIO-136 ] Polymeric scaffolds for applications into the glandular system Juan Morales-Corona ([email protected]) 1 , Omar Uribe 3 , Rafael Godinez-Fernández 2 , Atlantida Raya-Rivera 4 , Diego Esquilano-Rendon 4 , Roberto Olayo 1 1 Departamento de Física, Área de Polímeros, Universidad Autónoma Metropolitana, Unidad Iztapalapa 2 Departamento de Ingeniería Eléctrica, Universidad Autónoma Metropolitan 3 Posgrado en Ingeniería Biomédica, Universidad Autónoma Metropolitana 4 Tissue Engineering Laboratory, Infantile Hospital of Mexico, Federico Gómez Much of the body's organs and their functions are regulated by the glandular system, is responsible for hormones production. Any alteration in the hormones production 116 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla can alter or compromise the individual health. In this paper the use of scaffolds modified by plasma polymerization for use in the glandular system is presented. Scaffold of polylactic acid and polyglycolic acid coated with a thin film of polypyrrole doped in situ with iodine, PPy-I, and synthesized by plasma polymerization were cultured in vitro with both Leydig and Certoli cells to test the production of characteristic hormone, testosterone. The results indicate that in 1 to 81 days of the experiment, the cells continue to secrete the appropriate hormone. In another experiment, PPy-I nonoparticles were synthetized with atmospheric plasma. Agglomerates of PPy-I nanoparticles were tested in a culture of beta cell in vitro. The results indicate that beta cells are functional and attached to the PPy-I nanoparticles support. [ BIO-137 ] Nanomaterials incorporated into PCL to modify the biocompatibility. Erika Fragoso-Pérez ([email protected]) 1 , Roberto Olayo-Valles 1 , Juan Morales-Corona ([email protected]) 1 , Roberto Olayo 1 1 Departamento de Física, Área de Polímeros, Universidad Autónoma Metropolitana, Unidad Iztapalapa. Polymeric scaffolds electrospinning of polycaprolactone, PCL, allow the growth of different cell types such as hepatocytes, keratinocytes, neurons, etc. To mimic the extracellular matrix appropriate for the specific cell type to be cultivated should be incorporated into scaffolding that the cell must be able to use, such as proteins, magnetic nanoparticles or carbon nanotubes these may give mechanical reinforcement sensibility to electromagnetic signals, a great deal of work has been done in this direction lately. In this work, the addition of nanomaterials (carbon nanotubes and magnetic nanoparticles) into PCL electrospun fibers, for increased the mechanical properties and biocompatibility is presented, samples were characterized by SEM, Xray diffraction (SAXS and WAXS) and DSC. Through of electrospinning technique, polymeric PCL scaffolds were prepared with different concentrations of carbon nanotubes and magnetic nanoparticles embedded in the electrospun fibers. Once these scaffolds prepared were characterized by XRD, infrared spectroscopy in ATR mode, the crystallinity was analyzed by DSC, the Confocal- Raman signal is studied and electron microscopic analysis was performed (SEM). The authors thank the partial support from CONACyT through project CONACyT-15523 and Electron Microscopy Laboratory of the UAM-Iztapalapa. 117 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ BIO-173 ] Composite fibers of PLA-hydroxyapatitecarbon nanotubes for biomedical applications Ramon Román Doval ([email protected]) 2 , Mauricio Ortega López 3 , Juan Morales Corona 1 , Roberto Olayo Gonzalez 1 1 Departamento de Física Universidad Autónoma Metropolitana, Ave. San Rafael Atlixco No 186, Iztapalapa, Vicentina, México D. F. CP 09340, México. 2 Programa de Doctorado en Nanociencias y Nanotecnología. Centro de Investigación y de Estudios Avanzados del IPN. Av. IPN 2508, San Pedro Zacatenco, México D.F. C. P. 07360, México. 3 Sección de Electrónica del Estado Solido-Departamento de Ingeniería Eléctrica. Centro de Investigación y de Estudios Avanzados del IPN. Av. IPN 2508, San Pedro Zacatenco, México D. F. C. P. 07360, México The synthesis of carbon nanotubes (CNT) was made in an experimental reactor by the pyrolysis method. The CNT were purified by oxidation to eliminate the impurities. CNT were then functionalized to integrate carboxyl groups on the surface. Subsequently composite fibers were prepared by electrospinning from a solution containing functionalized CNT, poly (lactic acid) and hydroxyapatite. The composite fibers were characterized by TEM, SEM, FTIR, SAXS, and Raman-Confocal study. The composite fibers that were prepared could be used for biomedical applications. 118 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ BIO-174 ] Compatibilizers Use in Silicone-Ceramic Composites for High Voltage Applications Daniel Mendoza Gonzalez ([email protected]) 1 , Carlos Gómez Yáñez 1 , Fermín Pascual Espino Cortés 2 1 Department of Metallurgical and Materials Engineering, ESIQIE. National Polytechnic Institute, U. P. Adolfo López Mateos, Zacatenco, Mexico City, 07738, Mexico. 2 Graduate Section, Electrical Engineering, ESIME-Zacatenco. National Polytechnic Institute, U. P. Adolfo López Mateos, Zacatenco, Mexico City, 07738, Mexico. Nowadays electrical insulators are made of polymer composites because they offer greater lightness and the processing cost is low, because they not need high energy for the processing, respect made of ceramic for electrical power systems. Simulations about the distribution of electrical field in high permittivity non-ceramic insulator shows an important decreasing of the gradient of electrical field on insulator’s surface, the same that causes the appearance of leakage current and partial discharges, thus causing the dielectric breakdown of the insulator. Commonly BaTiO3 (BT) used as filler in silicone matrix due high dielectric constant and ferroelectric properties. Dispersion of BT particles in silicone and incompatibility of two surfaces of BT and silicone represents obstacle for obtaining high permittivity composite. On the one hand the incompatibility causes electric charge gradient interfase between the filler and the matrix, and their surfaces nature (hydrophilic and hydrophobic respectively) prevent the increasing of the dielectric constant of the composite to higher values, because there is no-connection between the ferroelectric filler and the polymer matrix. The using of Cetyl Trimethyl Ammonium Bromide (CTAB) and Sodium Dodecyl Sulfate (SDS) as compatibilizers can be a solution to create a connection between the ferroelectric particles and the polymer matrix for breaking the antagonist condition between both surfaces. On the other hand maintain a better dispersion of the BT particles can improve the dielectric constant following the Lichteneker´s law of composites. In this work a series of settling experiments were conducted in Water/BT/Surfactant systems; varying the surfactant concentration at fixed values of pH, all according the z potential of the inorganic filler. Results were analyzed and discussed to determinate the optimal process coating of BT particles. Studies with TGA-DTA and IR Spectrometry give information and evidence of the ceramic particles coating with surfactant selected. Furthermore, electrical simulations in COMSOL were performed to prognosticate the composite´s permittivity by effect of integration of a compatibilizer; results were analyzed conducting the composite manufacturing at fixed values of %Vol for BT. Results of electrical characterization was performed properly, showing an increase in composite’s permittivity due surfactant using 119 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla without sacrificing high resistivity that the polymer matrix having pure. SEM micrographs show the perfect integration of the ferroelectric particles in the polymer matrix. Keywords: Compatibilizer, No-ceramic outdoor insulator, Silicone-ceramic composite. [ BIO-180 ] Surface functionalization of magnetic nanoparticles by plasma polymerization Luis E. González-Calderón ([email protected]) 1 , Anilú SaucedoSariñana 3 , Omar E. Uribe-Juárez 2 , Roberto Olayo 1 , Roberto OlayoValles ([email protected]) 1 1 2 Departamento de Física, Universidad Autónoma Metropolitana - Unidad Iztapalapa Posgrado en Ingeniería Biomédica, Universidad Autónoma Metropolitana - Unidad Iztapalapa 3 Universidad Autónoma de Baja California There is wide interest in the use of magnetic nanoparticles for biomedical applications. The interaction of magnetic nanoparticles with tissues and cells can be mediated by modifying the surface of the nanoparticles. Typical methods for surface functionalization of magnetic nanoparticles include ligand grafting (either chemically or physically) and surface-initiated polymerization. In this work we demonstrate the possibility of modifying the surface of magnetic nanoparticles by plasma polymerization. Iron oxide nanoparticles were functionalized in a low-pressure reactor with a variety of monomers to obtain diverse surface functionalities. The interaction between the nanoparticles and cells was studied in vitro. Functionalized magnetic nanoparticles could be used for magnetic separation of cells from complex mixtures such as blood, and for magnetic fluid hyperthermia treatment of malignant tissues such as tumors. 120 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ BIO-183 ] Study of the photobactericide properties of psi layers infiltrated with Ti02 nanoparticles Karla M. Osorio-Alcántara ([email protected]) 2 , E. Gomez Barojas 1 , J. Carlos Benitez Serrano 2 , J. Albino Moreno Rodriguez 2 , E. Sanchez Mora 3 , R. Silva Gonzalez 3 1 CIDS-IC. Ed. 103-C, C.U. BUAP. Puebla, Pue. 72570. Facultad de Ciencias Químicas, BUAP. Puebla, Pue. 72570. 3 Instituto de Física, BUAP. Apdo. Postal J-48, Puebla, Pue. México 72570. 2 Since Sunada et al [1] discovered the photocatalytic destruction of microorganisms by the TiO2 the photocatalytic activity of many semiconductors compounds about the pathogenic micro organisms inhibition effect has been studied. In this work, we studied the photobactericide properties of porous silicon (PSi) layers infiltrated with TiO2 nanoparticles, using the E. coli as a biological model. The TiO2 nanoparticles were prepared by the sol-gel method with a solution that contained 100 mL of 2-propanol (Sigma-Aldrich 99.5%), 10 mL of deionized water and 5 g of polyvinylpyrrolidone (Sigma Aldrich 10-500G). Then, the solution was poured into a glass reactor three-ways and it was heated to T=40°C with constant agitation. Then, the titanium isopropoxide was drop by drop added, heated to 40°C and kept in agitation for 14 h. The solvent was extracted with a rotary vapor under reduced pressure. Then, the TiO2 powder was treated thermally at 45°C for 12 h. Furthermore, the TiO2 powder was grind in a mortar until becoming a fine powder. By SEM the diameter of the TiO2 particles were determined and are of the order of 20 nm. The energy band gap of TiO2 nanoparticles was determined from UV-Vis spectra and the value is of the order of 3.1 eV. To evaluate the antimicrobial activity of PSi infiltrated with TiO2 nanoparticles some bioautography trials were done. In agar Müller-Hinton plates, the matrices of proof were positioned. Later on, the bacterial strain suspension Escherichia coli ATCC 25922 adjusted to 0.5 of the MacFarland standard was added and incubated at 37°C for 24 h then, the halo inhibition zone was observed. Reference [1] Sunada K, Watanabe T, Hashimoto K. Bactericidal activity of copper-deposited TiO2 thin films under UV illumination. J. Environ. Sci. Technol. 37 (2003) 4785-4789. Acknowledgement. This work has been partially supported by VIEP-BUAP, Project GOBEEXC15-I. 121 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ BIO-212 ] Synthesis and characterization of N-doped reduced graphene oxide Rebeca Ortega Amaya ([email protected]) 3 , Yasuhiro Matsumoto 4 , Manuel Alejandro Perez Guzman 2 , Roberto Olayo Gonzalez 1 , Juan Morales Corona 1 , Mauricio Ortega Lopez 3 1 Departamento de Física, Universidad Autónoma Metropolitana Iztapalapa, Apto. Postal 55-534, CP 09340, México D.F., México 2 Programa de Doctorado en Nanociencias y Nanotecnología. CINVESTAV IPN, Av. IPN No. 2508, CP 07360, México D.F., México. 3 Sección de Electrónica del Estado Sólido, Departamento de Ingeniería Eléctrica, CINVESTAV, . Av. IPN No. 2508, CP 07360, México D.F., México 4 Sección de Electrónica del Estado Sólido, Departamento de Ingeniería Eléctrica, CINVESTAV. Av. IPN No. 2508, CP 07360, México D.F., México Now a days, graphene-based materials, including graphene oxide (GO), the oxidized forms of graphene, are under study because of their biocompatibility and unique physicochemical properties [1]. They are currently studied for applications in the technological areas of biomedicine, energy production, electronics and environmental remediation[2]. Reduced GO (rGO) has been applied in bone implants and bone tissue engineering, due their exceptional mechanical properties[3], and recently, nitrogen doped graphene was successfully proven as a useful sensing and electronic biomaterial, particularly, as a glucose biosensor[4]. In this work, we report our results on the synthesis and characterization of nitrogen (N) doped reduced graphene oxide (N-rGO). GO was first obtained by Hummer´s method and the resultant product was treated under a N2(g) plasma at different times. The samples were characterized by Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The XPS spectrum displays characteristics bands corresponding to quaternary N (or graphitic N), pyridinic N, and pyrrolic N. Remarkably, the N2 plasma processing simultaneously promotes the GO reduction and the N-doping. [1] W. Choi, I. Lahiri, R. Seelaboyina, and Y. S. Kang, "Synthesis of Graphene and Its Applications: A Review," Critical Reviews in Solid State and Materials Sciences, vol. 35, pp. 52-71, 2010/02/11 2010. [2] C. Chung, Y.-K. Kim, D. Shin, S.-R. Ryoo, B. H. Hong, and D.-H. Min, "Biomedical Applications of Graphene and Graphene Oxide," Accounts of Chemical Research, vol. 46, pp. 2211-2224, 2013/10/15 2013. [3] L. Bacakova, I. Kopova, L. Stankova, J. Liskova, J. Vacik, V. Lavrentiev, et al., "Bone cells in cultures on nanocarbon-based materials for potential bone tissue engineering: A review," physica status solidi (a), vol. 211, pp. 2688-2702, 2014. 122 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [4] M. M. Barsan, M. David, M. Florescu, L. Ţugulea, and C. M. A. Brett, "A new self-assembled layer-by-layer glucose biosensor based on chitosan biopolymer entrapped enzyme with nitrogen doped graphene," Bioelectrochemistry, vol. 99, pp. 46-52, 10// 2014. [ BIO-213 ] Synthesis and characterization of superparamagnetic cubical magnetite nanoparticles Manuel Alejandro Pérez Guzmán ([email protected]) 3 , Jaime Santoyo Salazar 1 , Enrique Campos Gonzalez 1 , Rebeca Ortega Amaya 4 , Yasuhiro Matusmoto 4 , Omar Felipe Fabela Sanchez 2 , Roberto Olayo Gonzalez 2 , Juan Morales Corona 2 , Mauricio Ortega Lopez 4 1 Departamento de Física, CINVESTAV IPN. Av. IPN No. 2508, CP 07360, México D.F., México. 2 Departamento de Física, Universidad Autónoma Metropolitana Iztapalapa, Apto. Postal 55-534, CP 09340, México D.F., México 3 Programa de Doctorado en Nanociencias y Nanotecnología. CINVESTAV IPN. Av. IPN No. 2508, CP 07360, México D.F., México. 4 Sección de Electrónica del Estado Sólido, Departamento de Ingeniería Eléctrica, CINVESTAV IPN, . Av. IPN No. 2508, CP 07360, México D.F., México Magnetite nanoparticles are under study due their biocompatibility, physicochemical and magnetic properties, they have applications in many technological areas like biomedical, electronics, energy and environmental remediation1. This work presents our recent advances on the synthesis and characterization of oleic-stabilized cubical magnetite nanoparticles prepared via an organic synthetical method. The nanoparticle morphological, structural and magnetic properties were characterized by TEM, XRD, and VSM. TEM revealed wellcrystallized and monodisperse 12 nm in size magnetite nanoparticles. The magnetite phase was corroborated by XRD. The hysteresis loop revealed the superparamagnetic character of our nanomaterial.The nanoparticles are suitable to be used on catalysis, bioremediation and hyperthermia cancer treatment2. 1. Lu, A., Magnetic Nanoparticles: Synthesis, Protection, Functionalization, and Application. Angewandte Chemie, 2007(46): p. 1222-1244. 2. Reiss, G., Magnetic Nanoparticles, in Handbook of Nanophysics: Nanoparticles and Quantum Dots. 2010, CRC Press. p. 2-1-2-13. 123 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ BIO-231 ] Electrospinning process optimization in obtaining nanofibers by response surface methodology (RSM) for applications in tissue engineering skin Josué Jiménez Vázquez ([email protected]) 1 , Eduardo San Martin Martinez 1 1 Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada del Instituto Politécnico Nacional, Legaria 694. Colonia Irrigación, 11500 México D. F. The electrospinning enables the production of polymeric nanofibers with diameters ranging from 3nm to 5um. Potential applications of the nanofibers produced by electrospinning include filtration membranes, catalytic nanofibers, fiber-based biosensors, and scaffolds for tissue engineering. For the study of the factors in the synthesis of nanofibers biopolymer (gelatin type B) through electrospinning, varying the parameters of solution concentration (% w / v), voltage (kV), distance from the tip of the needle to the collector (cm) and flow (ml / h). A central composite design (CCD) was used and diameter nanofibers variation was evaluated in each experiment by means of scanning electron microscopy (SEM). With data obtained a statistically adjusted mathematical model was performed which was used to obtain the surface response via Design Expert 7.0 software. The least significant parameters in the CCD were voltage and distance from the needle tip to collector, so these were held constant to determine nanofibers gelatin diameter response surface. The most significant parameters were solution concentration and biopolymer flow. It was determined through the response surface that the average diameter of the nanofibers increases with rising gelatin concentration to solution. It was found that the smaller diameter of the nanofibers can be obtained at a concentration of 10% (w / v) gelatin and a flow of 4 mL / h. 124 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ BIO-235 ] Experimental and Theoretical Analysis of Cellulose Nanowhiskers/Poly (Butyl Acrylate) Nelly Flores-Ramirez ([email protected]) 2 , Maria Guadalupe PinedaPimentel 2 , Salomon Ramiro Vasquez-Garcia 1 , Lada Domratcheva-Lvova 2 , Leandro García-Gonzalez 3 , Juan Carlos Farías Sanchez 2 1 Department of Chemistry Universidad Michoacana de San Nicolás de Hidalgo, Morelia, Mich. 58060, México 2 Department of Wood Engineering and Technology Universidad Michoacana de San Nicolás de Hidalgo, Morelia, Mich. 58060, México 3 Research Center in Micro and Nanotechnology of the UV Boca del Rio, Veracrúz, 94292, México Cellulose is an abundant polymer that can be obtained via numerous resources like plants, algae. Among various organic materials, cellulose is the most appropriate polymer to prepare various types of nanomaterials, has a nanostructured organization and unique properties; currently cellulose nanowhiskers (CNW) which are the highly ordered crystalline regions had been used as reinforcing material. The aim of this study was to investigate the miscibility between two components in a blend: nanowhiskers of cellulose (CNW) on poly(butyl acrylate) (PBA). These are an analysis of molecular configuration, orientations and intermolecular interactions in order to determine the adhesion and mechanical properties of materials obtained. Using acid hydrolysis CNW were prepared from wood cellulose, while the PBA was synthetized from solution polymerization. Additionally, CNW/PBA integration was carry out by incorporating CNW (0.1 and 0.5 wt%) into a PBA matrix. Then, the products were analyzed through molecular simulation (Accelrys Materials Studio) and a further analysis using (ATR) spectroscopy was for correlating results. The molecular simulation confirmed the existence of intra and intermolecular interactions in the systems analyzed and the cellulose exhibited molecular and flat linearity indicative cellulose crystallinity. Additionally intermolecular hydrogen bonding interactions and van der Waals forces were determined when the PBA was coupled to the Cellulose. 125 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ BIO-236 ] Interfacial Analysis of Chitosan/Bone: Cortical and Cancellous Bone matrices Christian Vianey Paz-Lopez 1 , Salomon Ramiro Vasquez-Garcia 1 , Nelly Flores-Ramirez ([email protected]) 2 1 Department of Chemistry Universidad Michoacana de San Nicolás de Hidalgo, Morelia, Mich. 58060, México 2 Department of Wood Engineering and Technology Universidad Michoacana de San Nicolás de Hidalgo, Morelia, Mich. 58060, México The stability and separation performance of a film can be tune by interfacial compatibility and interactions between the active film and the support. Considering the bioadhesion phenomena and principles, chitosan was used directly as the active layer in this study due to its superior film forming property and multiple interactions with bone. There were analyzed two types of bone substrates: cancellous and cortical bones. Thus, chitosan/bone samples were prepared by controllable dip-coating method under mild conditions. Experimental investigation was utilized to probe the interfacial compatibility and interaction of the chitosan with the bone substrates. Fourier transform infrared spectroscopy data revealed the strong interaction between the chitosan molecules and the substrate. Scanning electron microscope and microhardness analysis showed a moderate interfacial compatibility, while analysis by X-ray diffraction were used to identify the chitosan spatially structure, which increased their order on bone as a result of the increased acidity. 126 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ BIO-278 ] Evaluation of reactive resin on adhesive formulation of pressure sensitive adhesives Tzeitel Hernández Martínez ([email protected]) 1 , José Luis Rivera Armenta ([email protected]) 1 , Beatriz Adriana Salazar Cruz 1 , María Yolanda Chávez Cinco 1 , Ulises Paramo-García 1 1 División de Estudios de Posgrado e Investigación, Instituto Tecnológico de Ciudad Madero In developing adhesives it has been interest in incorporation or replace materials in the formulations to improve the performance thereof in accordance with the requirements of application, being more acceptable environmentally friendly materials. The adhesive performance is affected by the adhesive and cohesive properties that can be optimized by suitable selection of polymer, the nature or amount of adhesive resin and additive presences. In the present research, two styrenebutadiene-styrene (SBS) copolymer, one linear and one radial structure, in formulation of solvent-based contact adhesive were studied. The aim of use SBS copolymer, is to avoid the use of halogenated polymers in adhesive formulations due environmental regulations. Solubility tests in different solvents combination and suitable combination was selected according with hildebrand solubility parameter. To prevent precipitation of additives in adhesive formulation, an ultrasonic agitation was carried out before mixing the whole formulation. brookfield viscosity of adhesive formulation was determinated to identify the optimal polymer chains diffusion in the system and the adequate reactive resin amount. Rheological measurements were carried out to evaluate elastic modulus. Finally all characterization results were compared with commercial adhesive in order to assess the performance. 127 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ BIO-283 ] Thermal behavior effect of mix asphalt modified with radial SBS-Nanoclay composite Daniel Anzures 2 , Beatriz Adriana Salazar Cruz ([email protected]) 1 , José Luis Rivera Armenta ([email protected]) 1 , Nancy Patricia Díaz Zavala 1 , Ana María Mendoza Martínez 1 1 División de Estudios de Posgrado e Investigación, Instituto Tecnológico de Ciudad Madero 2 Instituto Tecnológico de Ciudad Madero The aim of present work was to evaluate the effect of adding of a nanocomposite obtained from an elastomeric matrix (radial styrene-butadiene-styrene copolymer, sbs) and a montmorillonite clay modified with a quaternary ammonium salt (cloisite 15a), to a virgin asphalt. the modifier (sbs-cloisite 15 a nanocomposite) was added in different amounts (up to 6% ) to asphalt. The asphalt properties such as viscosity and the thermal stability which influences the improvement of the failures as cracking and fatigue ressistence, increases with modifier addition. The obtained results of asphalt mixtures, show improvements in conventional properties such as penetration, softening point and thermal susceptibility. The thermal stability results shows that high temperature storage is stable when modifier is present in 4%. The rheological properties of asphalt-modifier mixtures were evaluated using a dynamic shear rheometer. The results show an improve in rheological properties compared with virgin asphalt, such as increasing elastic response (increase in complex modulus and decrease in the phase angle) evaluated at high temperature. The failure temperature was determinated by means on the guidelines of shrp standard getting higher values than virgin asphalt, proving therefore be a viable option to add the modifier to virgin asphalt. 128 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ BIO-316 ] Roll of solution and parameters deposition on PVP diameter nanofibers by electrospinning. Nadia Cruz Gonzalez ([email protected]) 1 , Jorge Roque de la Puente 2 , Miguel Angel Meléndez Lira 1 1 Department of Physics, CINVESTAV-IPN, Av. Instituto Politécnico Nacional 2508, col. San Pedro Zacatenco, Delegación Gustavo A. Madero, México D.F. C.P. 07360 2 Laboratorio Avanzado de Nanoscopía Electrónica – LANE-CINVESTAV, Av. Instituto Politécnico Nacional 2508, col. San Pedro Zacatenco, Delegación Gustavo A. Madero, México D.F. C.P. 07360 Electrospinning is a simple technique that has gained much attention because of its capability and feasibility in the fabrication of large quantities of fibers from polymer with diameters ranging in nanomicroscale [1,2]. These fibers provided high surface area to volume ratios, and it was of considerable interest for many applications, such as nanoparticle carriers in controlled release, scaffolds in tissue engineering, wound dressings, military wear with chemical and biological toxin-resistance, nanofibrous membranes or filters, and electronic sensors [3]. In a typical process, a polymer solution or melt is injected from a small nozzle under the influence of an electric field as strong as several kV/cm. The build up of electrostatic charges on the surface of a liquid droplet induces the formation of a jet, which is subsequently stretched to form a continuous ultrathin fiber. In the continuous-feeding mode, numerous copies of fibers can be formed within a period of time as short as a few seconds. characteristics such as fiber diameter, fiber morphology and the density of beads are strongly depending on the solution concentration, viscosity, surface tension and conductivity and process variables, such as applied voltage, needle diameter, flow rate and needle-to-collector distance. PVP exhibits unique properties, including solubility in water or in organic solvent. It has also very low toxicity, high complexing ability, good film forming characteristics and adhesive properties. Therefore PVP are widely used as polymer solution in to TiO2 and MoS2 nanofiber because is compatible with several Titanium and Molybdenum precursors. In the present work, PVP fibers with 8, 11 and 15 % weight using ethanol and DFM as solvent were prepared. Parameter deposition such as distance, high voltage needle diameter and flow rate were varied. Nanofibers obtained were characterized by Scanning Electron Microscopy. This work was financed by CONACYT project number CB2010-154857 and CONACYT postdoctoral fellow second call 2014, Referencia: CVU No.218308. [1]J. Doshi, D.H. Reneker, Electrospinning process and applications of electrospun fibers, J. Electrostat. 35 (1995) 151–160. [2] D.H. Reneker, I. Chun, Nanometre diameter fibres of polymer, produced by electrospinning, Nanotechnology 7 (1996) 216–223. [3] T. Kongkhlang, K. Tashiro, M. Kotaki, S. Chirachanchai, Electrospinning as a new technique to control the crystal morphology and molecular orientation of polyoxymethylene nanofibers, J. Am. Chem. Soc. 130 (2008) 15460–15466. 129 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ BIO-320 ] Characterization of the behavior of PPy-I in solutions of albumin and its application in a model of traumatic spinal cord injury. Omar Felipe Fabela-Sanchez ([email protected]) 4 , Luis MedinaTorres 5 , Stephania Sánchez-Torres 2 , Hermelinda Salgado–Ceballos 8 , Hermelinda Salgado–Ceballos 1 , Ana Laura Alvarez 4 , Rodrigo Mondragon 7 , M Guadalupe Olayo 7 , Guillermo J Cruz 7 , Juan Morales 3 , Araceli Díaz-Ruiz 6 , Camilo Rios 6 , Roberto Olayo 3 1 Centro de Investigación del Proyecto CAMINA A.C., México. Depto. Biología Celular, Universidad Autónoma Metropolitana, México. 3 Depto. Física. Universidad Autónoma Metropolitana, México. 4 Depto. Ingeniería Eléctrica. Universidad Autónoma Metropolitana, México. 5 Depto. Ingeniería Química, Universidad Nacional Autónoma de México, México. 6 Depto. Neuroquímica, Instituto Nacional de Neurología y Neurocirugía Manuel Velazco Suárez S.S.A. México. 7 Depto. Síntesis y Caracterización, Instituto Nacional en Investigaciones Nucleares, México. 8 Unidad de Investigación Médica en Enfermedades Neurológicas, Hospital de Especialidades, Centro Médico Nacional Siglo XXI, México. 2 Pyrrole is one of the most widely used monomers due to their easy availability, chemical stability and polarizability. It is therefore easy to obtain pyrrole derivatives by polymerization by synthetic methods such as: chemical, electrochemical and plasma energy; whereby it is possible to obtain surface coverages that have a wide variety of functional groups that make polypyrrole a good candidate for immobilization and / or coupling of biomolecules of interest in biomedical applications. In this study, we focused on presenting the characterization of iodine-doped polypyrrole (PPy-I) synthesized by plasma energy using techniques of study as XPS, SEM and TEM; as well as their rheological behavior as particles suspended in solutions of albumin (ALB) at different concentrations and two test temperatures. With the data obtained was possible to establish the PPy-I/ALB relationship to be supplied in a model of traumatic spinal cord injury in Long Evans rats strain in which functional recovery was evaluated by the Basso, Beattie, Bresnahan (BBB) scale. 130 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ BIO-332 ] Structure and interaction mechanism of a polyelectrolyte complex using dissipative particle dynamics. Efrain Meneses-Juárez ([email protected]) 1 , César MárquezBeltrán 1 , Juan Francisco Rivas-Silva 1 , Umapada Pal 1 , Minerva González-Melchor 1 1 Instituto de Fisica de la Benemerita Universidad Autonoma de Puebla. Av. San Claudio y Blvd. 18 sur. Col. San Manuel. Ciudad Universitaria. C.P. 72570 The mechanism of complex formation from tow oppositely charged linear polyelectrolytes dispersed in a solvent is investigated by using dissipative particle dynamics simulation. In the polyelectrolyte solution the size of the cationic polyelectrolyte remains constant while the size of the anionic chain increases. We analyze the influence of the anionic polyelectrolyte size and salt effect on the conformational changes of the chains when the complex is forming. The behavior of the radial distribution function, the end-to-end distance and the radius of gyration of each polyelectrolyte is examined. These results showed that the effectiveness of the complex formation is strongly influenced by the process of counterion release from the polyelectrolyte chains. Depending on the ratio of chain lengths, we have found that the formation of a compact complex or a lengthened structure can occur. 131 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ BIO-353 ] Behaviour of the compressive strength in modified mortars elaborated with recycled materials (aggregates and PET resin) Jose Ramon Orduño Apodaca ([email protected]) 2 , Jose Manuel Gomez Soberon 1 , Ramon Corral Higuera 2 , Susana Paola Arredondo Rea 2 , Andres Castro Beltran 2 , Ramon Alvaro Vargas Ortiz 2 , Jorge Luis Almaral Sanchez ([email protected]) 2 1 Departamento de Construcciones Arquitectónicas II Av. Doctor Marañón 44-50, 08028. Barcelona. España 2 Universidad Autónoma de Sinaloa Facultad de Ingeniería Mochis Fuente de Poseidón y Prol. Ángel Flores S/N Fracc. Las Fuentes Los Mochis, Sinaloa, México The problem of recycling waste materials of various kinds, is, and will be, undoubtedly, one of the problems that will most affect the society in the future and that we must address and resolve in all possible ways. Soft drink and mineral water bottles are all made of polyethylene terephthalate (PET) and constitute the third largest food packaging consumed. The production of such a large amount of PET bottles has created an environmental problem of gigantic proportions, since these bottles not reused become as plastic waste, which do not decompose readily in nature. To solve this problem is possible to recycle these post-consumer PET bottles. The demolished concrete to serve as a source as quality aggregate feed stock in a variety of applications. Such recycling operations have the added benefit of reducing landfill disposal, while conserving primary resources and reducing transport costs. Recycled demolition aggregate used to replace newly quarried limestone aggregate, usually used in coarse (6 mm) and fine (4 mm-to-dust) grading. This research focused on explaining the mechanical effects caused by addition of unsaturated polyester resin made from post-consumer bottles of PET (R-PET), cement-R- PET pastas and polymer modified mortars (PMM) with total or partial substitution of the recycled fine aggregate (RA) and additions of R-PET. The TGA and XRD results show that there is less development of the hydration products to a higher content of R-PET, causing reduction in the compressive strength of the PMM. 132 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ BIO-390 ] Thin films of polyaniline-TiO2 using synthesis by plasma Cuauhtémoc González Palacios ([email protected]) 3 , Elena Colín Orozco 3 , Guillermo Cruz Cruz 1 , Guadalupe Olayo González 1 , Juan Morales Corona 2 , Iván Martínez Cienfuegos 4 1 2 Departamento de Física, Instituto Nacional de Investigaciones Núcleares, ININ Departamento de Física, Universidad Autónoma Metropolitana,UAM-IZTAPALAPA 3 Facultad de Ingeniería, Universidad Autónoma del Estado de México, UAEMex 4 Facultad de Ingeniería, Universidad Autónoma del Estado de México,UAEMex Is currently seeking new materials with higher efficiency in absorption of solar energy for application in solar cells, an example of these are the matrix composite polymersemiconductor for the application. Polymer conjugates with a full load balancing only will be a semiconductor, i.e. it must have a gap of energy between the valence band and the conduction, however breaks the energy balance through oxidation or reduction of electron, increases the number of carriers and the electrical conductivity is favored by several orders of magnitude. This paper reports the synthesis and characterization of films composed of polyaniline-TiO2 (PAn/TiO2) using the technique of synthesis by plasma, and the analysis of their morphological properties, through scanning electronic microscopy and optical, functional groups present on the surface with an analysis of infrared spectroscopy, and electrical conductivity as a function of temperature. The results show films with agglomerate formation and the incorporation of TiO2on the surface of the polymer. The electrical conductivity was favoured by an order of magnitude that is due to the presence of functional groups in the surface. 133 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ BIO-391 ] Activation energy of thin films of doped fullerenes polypyrrol (PPy/C60-C70) Elena Colín Orozco ([email protected]) 3 , Cuauhtémoc Palacios González 3 , María Guadalupe Olayo González 1 , Guillermo Cruz Cruz 1 , Juan Morales Corona 2 , Miriam Sánchez Pozos 3 1 2 Departamento de Física, Instituto Nacional de Investigaciones Núcleares, ININ Departamento de Física, Universidad Autónoma metropolitana, UAM-IZTAPALAPA 3 Facultad de Ingenieria, Universidad Autónoma del Estado de México, UAEMex Recently, polymers have been used as matrix for the development of composite materials due to the good adhesion with other elements, resistance to corrosive environments and electrical conductivity. When joins them to the polymer chain any other material in this case Fullerenes are structural, electronic and spectroscopic properties that can be studied in the obtaining of composites and thin films that improve efficiency. The objective of this work is to study the activation energy of compounds of PPy /C60 -C70 synthesized by polymerization technique by plasma to different power values. We report the synthesis and characterization of thin films, the study of the electrical properties, structural composition using the electronic microscopy: scanning and optics, as well as thermogravimetric analysis. The results show the formation of films with crowds on the surface. The electrical conductivity was favoured up to orders of magnitude, while de activation energy was 0.34 - 0.54 eV for each the compounds synthesized. 134 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ BIO-417 ] Modifying the surface of the macroporous silicon for use in biosensors. Xairo León Valiente ([email protected]) 1 , Ana Maria Gennaro 2 , Edith Osorio de la Rosa 1 , Hector Juárez Santiesteban 1 , Mauricio Pacio Castillo 1 , Roberto Roman Koropecki 2 1 Centro de Investigación en Dispositivos Semiconductores, Universidad Autónoma de Puebla CIDS-ICUAP 2 Grupo de Semiconductores Nanoestructurados, Instituto de Física del Litoral (CONICETUNL) In this paper the results of surface functionalization of macroporous silicon substrates are presented. It is intended to introduce lipids in the form of liposomes, lipid bilayers to build on the inner surface of the pores, for which the surface should be hydrophilic. It seeks to achieve this by oxidizing the surface so incorporated in the form of HO- hydroxyl radicals. Initially the macro-porous silicon is obtained from the anodising a silicon wafer monocrystalline p-type with (100) orientation and resistivity of 30-50 Ω-cm, in a solution of HF (50%) and dimethylformamide (DMF) by volume (1: 9). A current density of 10 mA/cm2 was used, anodization time was 1500 s. After anodising the surface of the sample was subjected to functionalization, four methods, (1) a solution of tetrabutylammonium hydroxide (HTBA) 1% was used, (2) the sample was placed in a solution of hydrogen peroxide (H2O2) 30% w / V, (3) the functionalization was performed using rapid thermal annealing (RTA) and (4) in a solution of 1% KOH for 60 seconds. Functionalization posttreatment samples were characterized by infrared Fourier transform spectroscopy (FTIR). The FTIR spectra of all the samples show the characteristic peak of hydroxyl groups (OH) 3000 cm-1. The introduction of liposomes was verified by FTIR spectroscopy, which proves hydrophilicity. A systematic study varying the conditions and methods of oxidation was performed. EPR spectroscopy and theoretical-experimental settings the amount of lipids forming lipid bilayers at the surface of the pores and the amount of lipids remained in the form of unilamellar liposomes were obtained. Keywords: Silicon macroporous, Lipids, functionalization 135 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ BIO-434 ] Biosensor development using gold nanoparticles and lectins Angel Netzahual Lopantzi 1 , Jose Francisco Sanchez Ramirez 1 , Orlando Zaca Moran 1 , Abdu Orduña Diaz 1 , Marlon Rojas Lopez 1 , Raul Delgado Macui 1 , Valentin Lopez Gayou ([email protected]) 1 , Julio Reyes Leyva 2 1 2 CIBA-IPN, Tlaxcala, 90700, Mexico CIBIOR-IMSS Metepec, Puebla, Méx. A biosensor is a device integrated of a biological recognition element and transductor that provide qualitative or quantitative information, between they there are biosensors optics that provide information spectroscopy such as fluorescence, absorption, scattering and reflection. These biosensors have been applied in areas such as security food, environmental and biomedical. These biosensors used different molecules (biological recognition element) that have ability to detect of mode specifically and high sensitivity other molecules. So that the assembly of these biosensors is critical to get optimal results; in this work we develop an experimental protocol for assembly a biosensor integrated of gold nanoparticles (transductor) coupled to lectins (biological recognition element). Gold nanoparticles were obtained by reduction method in presence ions metals and using chitosan as agent reductant and stabilizer, this polymer has capacity of functionalized surface nanoparticles with group’s hydroxyls which allow us to bind the lectin. The assembly between the nanoparticle and the lectin was realized to pH 7. Each stage including the synthesis, the conditioning and the assembly of lectin was analyzed by applying UV/Vis and Infrared spectroscopy, together with Transmission Electron Microscopy (TEM). 136 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ BIO-453 ] Methodology to obtain hydroxyapatite with different crystalline quality of pork bone Andrea Yáñez ([email protected]) 2 , Mario Enrique Rodriguez Garcia ([email protected]) 1 1 Centro de Física Aplicada y Tecnología Avanzada, Universidad Nacional Autónoma de Mexico Campus Juriquilla, Qro., Mexico 2 Ingenieria Física, Faculta de Ingeniería, Universidad Autónoma de Queretaro Bio-ceramics are biomaterials whose main characteristic is that can be use in medicine, for example, in prosthesis. Hydroxyapatite is a bio-ceramic composed by calcium, hydrogen, oxygen and phosphorus, which chemical formula is (Ca10[PO4]6[OH]2). In nature it could be find in bones of vertebral animals, dentin and exoskeletons. In this project crystal hydroxyapatite will be obtain using cortical pork bone found in the femur. The methodology that was used to obtain hydroxyapatite consist in a hydrothermal and calcination process, the objective is that no chemicals will be used in the process. The steps to obtain hydroxyapatite will be separated in four sections, each one with a description. 1. First clean o Cook the cortical pork bone with distilled water using a pressure cooker, it will be easier to take off the meat that the bone may have. o When the bones doesn’t have meat, put them to dry in an oven for 6 days, with constant temperature 90°C. o Take out the bones and cook them with distilled water using a pressure cooker. o After 1 hour of being in the pressure cooker, put them to dry in an oven for 1 day at 90°C. 2. Pulverization Using a metal mortar hit the bones until they have a size of 5 mm. With a rock miller the bones are milling in order to obtain powder. Homogenize the powder of bone using an 80 mesh sieve. 3. second clean When the powder is already homogeneous it will have a second clean. Cook the powder with distilled water at 1:10 in a pressure cooker, for 6 minutes, trying to lost the smallest amount of powder. 137 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla Dry the powder in an oven with a temperature of 90°C, for 1 day. 4.Incineration In this step two variables are controlled: incineration time and heating rate, following the next steps: Increase the temperature with a velocity of 5°C per minute until it reach 600°C. Incinerate for 3 hours at this temperature, them change the velocity of heating rate to 2.5 , 5.0, and 7.7 °C/min up to 700, 800, 900, and 1000 °C. In this work we obtained hydroxyapatite without any chemical reaction and different crystalline qualities just controlling the time of calcination and the velocity of the ramp of heating. [ BIO-456 ] Granular formation’s kinetic of BIO-HAP in function of temperature Sandra Milena Londoño Restrepo 1 , Mario Enrique Rodriguez Garcia ([email protected]) 1 1 Centro de Física Aplicada y Tecnología Avanzada, Universidad Nacional Autónoma de Mexico Campus Juriquilla, Qro., Mexico Hydroxyapatite (Hap) is a stoichiometric material with formula: Ca10(PO4)6OH2, while, biohydroxyapatite (Bio-Hap) is a non-stoichiometric ceramic that contain mineral traces, such as, Na, K, Cr, Fe, Mg, Mn, and others. The importance of Bio-Hap is growing due to medical applications, like, maxillofacial surgery, coating metallic implants, dental fillings, and others. In addition, HAp is employed in chromatography, catalysis, and genomic medicine. In this work, the effect of heating rate on granular formation’s kinetics of BioHAp was studied. To determine the effects on physicochemical properties, the biologic material (bovine bone powder) was calcined at 600, 700, 800, 900, 1000, and 1100°C, employing two different heating rates (2.5 and 5 °C/min), and a characterization point to point was performed. The HAp sample taken from bovine bone was obtained by hydrothermal process and calcination. Physicochemical properties characterization was realized by different methods like X-ray diffraction (XRD), Raman spectroscopy, Scanning Electron Microscopy (SEM), Thermogravimetric analysis (TG) and Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). XRD was used to study the structural behavior as well as the crystalline quality. Raman was carried out in order to identify the 138 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla functional groups of HAp and monitor the removal of organic material. The surface morphology was analyzed by SEM. Thermal degradation was established by TG and ICPOES was used in order to establish the elemental composition. We found that high temperatures and slow heating rates produce a single crystal of Bio-Hap with high crystalline quality of hydroxyapatite. Keywords: Hydroxyapatite, heating rate, crystalline quality, kinetic. References Akram M., Ahmed R., Shakir I., Wan Ibrahim W.A., Hussain R. (2014). Extracting hydroxyapatite and its precursors from natural resources. Journal of Material Science, 49, 1461–1475. Campa Molina J., Ulloa Godínez G.S., Bucio Galindo L., Belío I.A., Velazquez R., Rivera Muñoz E.M. (2007). Biomateriales: Fundamentos, técnicas y aplicaciones. Universidad de Guadalajara, México. Kusrini E., Sontang M. (2012). Characterization of x-ray diffraction and electron spin resonance: Effects of sintering time and temperature on bovine hydroxyapatite. Radiation Physics and Chemistry, 81, 118–125. Sofronia A.M., Baies R., Anghel E.M., Marinescu C.A., Tanasescu S. (2014). Thermal and structural characterization of synthetic and natural nanocrystalline hydroxyapatite. Materials Science and Engineering C, 43, 153–163. 139 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ BIO-474 ] manufacture of membranes of a-SiC:H for biosensor applications Oscar Mauricio Gelvez Lizarazo ([email protected]) 2 , José Herrera-Celis ([email protected]) 2 , Claudia Reyes-Betanzo 2 , Abdu Orduña-Díaz 1 1 Centro de Investigación en Biotecnología Aplicada del Instituto Politécnico Nacional, ExHacienda San JuanMolino Carretera Estatal Tecuexcomac-Tepetitla Km 1.5, C.P. 90700, Tlaxcala-México 2 Electronics Department, National Institute of Astrophysics, Optics and Electronics INAOE, Luis Enrique Erro 1, Santa María Tonatzintla, 72840 Pue In order to develop biosensors based on membranes, a-SiC:H films has been deposited by PECVD on silicon substrate, the residual stress of the films has been reduced through a annealing, and wet and dry etching of silicon has been made. Characterization of the residual stress and roughness of the deposited films was performed using surface profilometry and atomic force microscopy, respectively. By the annealing at 450 °C under nitrogen atmosphere, residual stress was reduced by 75%, improving the structural stability of the membranes. The etch rates of silicon with hydrofluoric acid, potassium hydroxide and HNA solutions (HF+HNO3+CH3COOH) were obtained, resulting in a etch rate as high as 18.6 μm/min. The dry etching was made using SF6 as precursor gas and a etch rate of 5.44 μm/min was achieved in this case. Finally, the a-SiC:H biocompatibility was assessed by testing the bacterial attachment of gram negative bacillus using Enterotoxigenic Escherichia coli (ETEC), proving the nontoxicity and the good adhesion of the biological agent with the material. Acknowledgment The authors are thankful to Mayra Gonzalez Quintero and Dra. Elsa Iracena Castañeda Roldán by for their cooperation and support in the process of fixing bacteria developed in Laboratorio de patogenicidad microbiana del Departamento de Investigaciones Microbiológicas en el Instituto de ciencias de la Universidad Autónoma de Puebla (ICUAP). 140 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ BIO-513 ] Chitosan films composites with the sistem hydroxyapatite/ silver phosphate. Gerardo Pozos Sanchez ([email protected]) 3 , Efraín Rubio Rosas ([email protected]) 1 , Erick Reyes Cervantes 2 1 Centro Uiversitario de Vinculación y Transferencia de Tecnología Prolongación de la 24 Sur y Av. San Claudio, Ciudad Universitaria, Col. San Manuel, 72570 Heróica Puebla de Zaragoza, Pue. 2 Centro Universitario de Vinculación y Transferencia de Tecnología Prolongación de la 24 Sur y Av. San Claudio, Ciudad Universitaria, Col. San Manuel, 72570 Heróica Puebla de Zaragoza, Pue. 3 Facultad de Ingeniería Química BUAP, Edificio 105 H, Prolongación 14 Sur s/n, Ciudad Universitaria, 72570 Heróica Puebla de Zaragoza, Pue. Chitosan and hydroxyapatite are materials that be found inside of the human body, but it doesn’t have a good antimicrobial activity, if silver phosphates is added it can be inhibit growth of some kind of bacteria, proposing a possible application as a material for bone filling or bags for sterilization of material for laboratory. The aim of this work was the synthesis and characterization of composite films of chitosan with hydroxyapatite and silver phosphate system. The first step was the synthesis of hydroxyapatite (Hap) by the precipitation method, the second step was the precipitation of silver phosphate Ag3PO4, once they obtained the system chitosan films were made with this ceramic material, to different concentrations of Hap/Ag3PO4 (0, 50 y 70%), for comparison therebetween. The preparation of the films was by varying the pH, thereby achieving obtain firm and flexible films. XRD to characterize the films was performed to confirm the presence of crystals of Ag3PO4, SEM to observe the morphology of the film, FTIR to detect the presence of hydroxyl group (OH)1 and the phosphate group(PO)-3. The results of the characterizations suggested that the ceramic material maintained its structure unmodified chitosan film. 141 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ BIO-514 ] Mechanical behavior of PCL and PLA blends used for biomedical applications. J. Dominguez 2 , G. Martinez 2 , E. Reyes-Alcocer 2 , J. Vazquez-Coello 2 , J. A. Solís-Ruíz 1 , A. May-Pat 3 , G.M. Alonzo-Medina ([email protected]) 1 1 División de Ingeniería, Universidad Anáhuac-Mayab 2 Emot Ingeniería S.A. de C.V 3 Unidad de materiales, Centro de Investigación Científica de Yucatán, A.C In the last years, the use of biodegradable polymers have been of great importance in biomedical field. The biopolymers are widely used in traditional applications, such as matrices for long-term drug delivery [1-2], short-term fixation devices in the orthopedic field [2] and surgical sutures [3]. Polylactic acid (PLA) and Polycaprolactone (PCL) are aliphatic polyesters more used due to their excellent biodegradability, biocompatibility and bioresorbability [4]. This work is aimed to study of blends of Polylactic acid (PLA) and Polycaprolactone (PCL) and their mechanical behavior. Five formulations of these blends were proposed (PCL/PLA), 90/10, 85/15, 80/20 and 70/30. The formulations were prepared through a mixed chamber. The samples were studied by tensile test with a Shimadzu universal testing machine. In addition the samples were characterized by mean of FTIR and contact angle technique in order to study the organization of chains of the blends and the wettability of surface of blends (a way to quantify the hydrophilic behavior of the material) respectively. The objetive of this study is obtain a polymeric biomaterial, combining the properties of PLA (high strength and low elongation at break value) and the thermoplastic behavior of PCL, and that can be used to multiple biomedical applications. References [1] Jinhui Zhang, Jia Xu , Hongyan Wang , Weiqun Jin and Junfeng Li Materials Science and Engineering C 29 (2009) 889–893 [2] J. Heller, J. Control. Release 2 (1985) 167. [3] B. Jeong, Y.H. Bae, D.S. Lee, S.W. Kim, Nature 388 (1997) 860. [4] D. Kobayashi, S. Tsubuku, H. Yamanaka, M. Asano, M. Miyajima, M. Yoshida, Drug Dev. Ind. Pharm. 24 (9) (1998) 819. 142 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ BIO-515 ] Residual Cellulose Films Karla de lázaro gasca ([email protected]) 2 , Heriberto Hernandez Cocoletzi ([email protected]) 2 , Eva Águila Almanza 2 , Efrain Rubio Rosas 1 1 Centro Universitario de Vinculación y Transferencia Tecnológica, Prolongación de la 24 Sur y Av. San claudio, Ciudad Universitaria, Col. San Manuel 2 Facultad de Ingeniería Química, BUAP, Av. San Claudio y 18 sur S/N CU, San Manuel Edif. 106H Cellulose is the most abundant organic biomolecule as it forms the most of the Earth's biomass [1]. It is characterized by its high availability. For example, it contained in the corn leaf, that most of society is a common waste producing damage to the environment; therefore, it obliges us to reuse these waste for some benefit of our society. It has now been studied for creating new materials [2]. In this work the production of cellulose film intended by corn leaves is performed. Residual leaves are collected, subsequently spraying them with a conventional coffee mill until pulverization and sift 200 and 250 mesh; after that the samples were characterized by X-ray diffraction, optical microscopy and infrared spectroscopy. Then, cellulose films were obtained by using two different particle sizes. For the preparation of the films was used: Corn leaf spray (0.10 y 0.15 g), glycerol monostearate :( 2 y 3.5 mL), 3.5 mL of sorbitol, 3.5 mL starch. Each of the materials was added under vigorous stirring and heating from about 50 ° C for 30 minutes. It was allowed to cool to room temperature then left in a drying oven for 24 hours at 60 °C. The films were characterized by X-ray diffraction, Infrared spectroscopy and scanning electron microscopy. References [1] Tatsuya H. Glyn O.P., New Fibers (Chapter 8; Cellulosic Fibers), Woodhead Publishing Limited, Cambridge England, 2da. Ed, 1997, 181-208. [2] Averous, L., Boquillon, N. (2004) Carbohydrate Polymers, 50, 111 Acknowledgements: This work has been partially supported by VIEP- BUAP. 143 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ BIO-571 ] Optical performance of thermochromic inks modified with TiO2 nanoparticles Marcelo Martínez-Puente ([email protected]) 1 , Francisco Servando Aguirre-Tostado ([email protected]) 1 , Eduardo Martínez-Guerra 1 1 CIMAV-Monterrey, Alianza Norte 202, Parque PIIT, Apodaca, N.L., México 66628. Color changing compounds have become increasingly important in recent years in the study and the production of thermochromics coatings, changing reversibly their color from darker to lighter tones as temperatures rises. The transition is achieved by a thermally reversible transformation of the molecular structure of the pigments that produces a spectral change of visible color. Thermochromic organic inks are being attractive for some industrial applications however UV degradation is a main problem that must be solved to protect the optical coating quality. Inorganic UV blockers are usually semiconductor oxides such us TiO2. TiO2 has good ultraviolet blocking power and is very attractive because of such as advantages as nontoxicity, chemical stability at high temperature, and permanent stability under UV exposure. The mechanism of UV-blocking of TiO2 is so far not very clear. Given the mixed and often conflicting views, it appears desirable for a thorough investigation on the problem. Coatings have been produced on glass substrates using available organic thermochromics pigments incorporated into an appropriate binder system to develop a blue thermochromic ink. In order to examine the behavior of a blue thermochromic pigment two groups of samples were prepared: the first group consisted of the blue thermochromic pigment and the binder for different concentrations, and the second comprised of the blue thermochromic pigment, the binder and titanium dioxide nanoparticles (TiO2 Nps). The aim of this investigation was to study systematically the influence of different additions of TiO2 nanoparticles as a UV-blocking additive for thermochromic coatings. Thermochromic inks with nanoparticles were prepared through ultrasonic dispersions and adding them into solvent with the adequate rheology to be applied by gravity-feed spray gun on glass substrates. Visible images were taken at different temperatures from 25 °C up to 45 °C to determine the thermochromic transition (TT) using a stereoscopic microscope equipped with a camera with a constant aperture of the lens in order to take pictures with the same color and intensity reference. The glass substrates were heated from ambient temperature to 40 °C taking pictures with ΔT of 1 °C and processing them by computer taking samples of color in a specific zone and plotting the RGB coordinates. UV/VIS/NIR spectrophotometer (Varian Cary 5000) was used for measuring the absorbance spectra of the samples. Coatings without TiO2 are translucent on glass; meanwhile the presence of TiO2 gives hiding power to the coating which means that TiO2 Nps give the ability to lighten the surface over the intrinsic color of blue thermochromic. Thermochromic coatings are presented at their colored phase for temperatures lower than 30 °C, while their color starts to fade and they are becoming 144 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla colorless as their temperature overpasses the TT. A slight displacement of TT is observed for high loads of TiO2 Nps. The absorption spectra were collected for all samples, blue thermochromic coatings without TiO2 Nps and blue thermochromic coatings with different additions of TiO2 Nps. Because of its stronger UV absorptance, nanoscale TiO2 exhibits better UVblocking capacity than that of macroscale TiO2, however, it exerts very little influence when embedded in thermochromics matrix because of strong scattering phenomena. [BIO-572]Obtaining the extracellular matrix of the small intestine of a rat J. Reyes-Fernandez1, B. Zenteno-Mateo2, M. López-Fuentes1, M. PortilloSampedroa, M. Cárdenas-García3, J. A. Rivera-Marquez1, M. C. MendozaHerrera1, O. Olivares-Xometl1, Gregorio H. Cocoletzi4 1 Facultad de Ingeniería Química, Benemérita Universidad Autónoma de Puebla. Av. San Claudio y 18 Sur, Edificio FIQ1, C.U., Col. San Manuel, 72570, Puebla, Pue., México. 2 Facultad de Ingeniería, Benemérita Universidad Autónoma de Puebla. Boulevard Valsequillo esquina Av. San Claudio s/n, C.U., Col. San Manuel 72570, Puebla, Pue., México. 3 Facultad de Medicina, Benemérita Universidad Autónoma de Puebla, 13 Sur 2702, 72410, Puebla, Pue., México. 4 Instituto de Física Benemérita Universidad Autónoma de Puebla. Av. San Claudio y 18 Sur, C.U., Col. San Manuel, 72570, Puebla, Pue., México. The objective of this study is to obtain a shaped support decellularized three-dimensional tissue from the intestine of a rat using enzymatic treatments, ionic and nonionic surfactants. The method of production of an extracellular matrix is described from the intestine of a rat. Results are presented by observation of stained tissue by optical microscopy to check the total sample decellularization, IR spectroscopy to discard the presence of trace amounts of the reagents used and the presence of collagen tissue and scanning electron microscopy to verify scaffolding structure. 1. Longo, D. L. (2012), Harrison: Principios de Medicina Interna (18ª ed.), México: Mc Graw-Hill 2. Maghsoudlou, P., Totonelli, G., Loukogeorgakis, S. P., Eaton, S., De Coppi, P. A. Decellularization Methodology for the Production of a Natural Acellular Intestinal Matrix. J. Vis. Exp. (80), e50658, doi:10.3791/50658 (2013). This work has been partially supported by projects VIEP 2015, Mexico. 145 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla CHARACTERIZATION AND METROLOGY (CHM) Chairman: Roberto Machorro ( CNyN-UNAM) Sesión Oral [ CHM-24 ] Thermoluminescence, Raman and Morphological Studies of Sub-microsized Diamonds Grown in a Homemade HFCVD Reactor Rafael Garcia Gutierrez ([email protected]) 3 , Jorge Montes Gutierrez 2 , Marcelino Barboza Flores 3 , Rodrigo Melendrez Amaviza 3 , Oscar Contreras Lopez 1 1 Centro de Nanociencia y Nanotecnología, Universidad Nacional Autónoma de México, Apdo. Postal 14, C.P. 22800, Ensenada, Baja California, México 2 Departamento de Física, Universidad de Sonora, Apdo. Postal5-088,C.P. 8300, Hermosillo,Sonora, México 3 Departamento de Investigación en Física, Universidad de Sonora, Hermosillo,Sonora,Apdo. Postal5-088, C.P. 8300, México Micro- and nano-diamonds have been studied for their thermoluminiscence properties in dosimetry field and also due to its no-toxic bio-compatibility diamond has been used recently in the industry of biosensors. In this research, a novel and inexpensive method for synthesizing sub-microdiamonds on silicon is presented. The technique involves Chemical Vapor Deposition using a hot filament as activator of hydrogen at relative low pressures (~150 Torr). Using a CH 4:H2 mixture of gases, a thermal decomposition was conducted in a horizontal quartz-tube reactor at 2200 °C filament temperature and 1000 °C substrate temperature, yielding sub-microcrystalline diamonds. The micro-diamonds synthetized by this method have a spherical shape and consists of a mixture of micro- and nano-sized crystallites. The diamonds synthesized in this work showed 146 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla excellent RAMAN and TL signals. Due to these excellent properties, diamonds obtained by this technique could be applied as-synthesized in energy and biomedical industry. [ CHM-41 ] Comparison of microstructural and mechanical properties behavior of recovering cold work tool steel molds by GTAW and HVOF welding process A. Lozano Valle([email protected])1, M. A. Solís Alvarez1 C. Guevara Chávez2 J. L. Acevedo Dávila2 1 861 Steel Solution S. A. de C. V. Calle Paseo de los mirlos 533 Col. Lomas de Lourdes Saltillo Coahuila C.P. 25090 México. 2 Corporación Mexicana de Investigación en Materiales (COMIMSA), Calle ciencia y tecnología No. 790, Col. Saltillo 400, cp. 25290, Coahuila, México. This research studies the influence of the processing parameters on the mechanical and microstructural properties of a Diamalloy 1008 (Fe-Cr-Mo alloy) coating applied with high velocity oxi-fuel (HVOF) and five different electrodes types were applied by Gas tungsten Arc Welding (GTAW) on cold work tool steel mold specimens. The aim of these coatings is commonly used as a protection against corrosion and wear, but they also have the capacity to recover damaged areas as toolbox for automotive stamp. The specimens were characterized by optical and scanning electron microscopy to evaluate the quality of the covering material in the substrate; Vickers microhardness and Pin-ON-Disc were used to quantify the mechanical performance of the coatings. In the results it was observed a clearly better performance of the HVOF coating due the absence of fragile microstructure phases like a martensite and the formation of carbides M23C6 and M6C7. Key Words: HVOF, GTAW, toolbox, Wear. 147 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla INVITED TALK [ CHM-215 ] The satellites in the photoemission spectra of the 2p core level of transition-metals Alberto Herrera Herrera-Gomez ([email protected]) 2 , Dagoberto Cabrera-German 2 , Gustavo Gomez-Sosa 2 , Jorge-Adalberto Huerta-Ruelas 1 , Wencel de la Cruz Hernández 3 , Jorge-Alejandro TorresOchoa 2 , Julio Mata-Salazar 2 , Cynthia-Iveth Negrete-Martinez 2 , Gabriela Molar-Velazquez 2 1 2 CICATA-Queretaro CINVESTAV-Unidad Queretaro 3 CNyN-UNAM The shake-up satellites in XPS spectra are due to intrinsic energy losses as the photoelectron leaves the hosting atom. The first row transition metals, either in the metallic or in the oxide form (and sometimes in both), display clear shake-up features in the corresponding 2p core level. They are difficult to quantify because the shape of the main 2p peaks of these elements are highly asymmetric and the spectra contains a large background contribution. In fact, there is a frequent correlation between the presence of shake-up satellites and a large background intensity and, also, a large peak shape asymmetry. Through newly developed procedures it has been possible to properly fit all these core levels. In addition to those already described in the literature, the procedures allowed for pinpointing previously unreported shake-up satellites. A common feature of the satellites is that their spin-orbit splitting exhibits a remarkable difference with the associated to the main peak, suggesting angular-dependent correlation effects. 148 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ CHM-224 ] Characterization of luminescent samarium doped TiO2 nanocomposites synthesized by microwave using benzyl alcohol route Ranferi Domínguez Domínguez ([email protected]) 1 , Ranferi Domínguez Domínguez ([email protected]) 4 , Miguel Ángel Aguilar Frutis 1 , Gilberto Alarcon Flores 1 , Ciro Falcony 2 , Jorge Luis González Velázquez 4 , Raúl Iván Sánchez Alarcon 1 , Diego Israel Rivas López 3 , Héctor Javier Dorantes Rosales 3 1 Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Calzada Legaria No. 694, Miguel Hidalgo, Irrigación, 11500 Ciudad de México, D.F. 2 Centro de Investigación y de Estudios Avanzados, Av. Instituto Politécnico Nacional No. 2508, Colonia San Pedro Zacatenco, CP 07360, Ciudad de México D.F., México. 3 Escuela Superior de Ingenieria Quimica e Industrias Extractivas, Nueva Industrial Vallejo, Gustavo A. Madero, Ciudad de México, D.F 4 Escuela Superior de Ingenieria Quimica e Industrias Extractivas, Nueva Industrial Vallejo, Gustavo A. Madero, Ciudad de México, D.F The structural and luminescent properties of samarium-doped titanium dioxide hybrid organic-inorganic nanocomposites synthesized by microwave using benzyl alcohol route at several heat treatment temperatures are reported. These nanocomposites are nanocrystalline and present a tetragonal (anatase) crystal structure of the titania as determined by x-ray diffraction. The photo- and cathodoluminescence characteristics of these nanocomposites were studied as a function of the synthesis parameters such as heat treatment and samarium concentration. Excitation with a wavelength of 360 nm resulted in photoluminescent emission peaks located at 584, 613, 621, 664, 670 and 726 nm, associated with the electronic transitions of the Sm3+ ion. That photoluminescence intensity increased as a function of the treatment temperature was observed. Also, with increasing doping concentration, a quenching of the photoluminescence is observed. The chemical composition and surface morphology characteristics of the nanocomposites are also reported. The authors acknowledge the financial aid to carry out this work to Secretaría de Investigación y Posgrado del INSTITUTO POLITECNICO NACIONAL, grant # 20151093. 149 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ CHM-288 ] The Shirley background of the Tougaard background in the photoemission spectra of transition metals Dagoberto Cabrera-German ([email protected]) 1 , Jorge Alejandro Torres-Ochoa 1 , Gabriela Molar-Velazquez 1 , Gustavo GómezSosa 1 , Wencel de la Cruz 2 , Alberto Herrera-Gomez ([email protected]) 1 1 2 CINVESTAV-Unidad Querétaro, Querétaro 76230, México Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México, Km 107 Carretera Tijuana-Ensenada, Ensenada B.C., México The 2p core level photoemission spectra of transition metals present a very intense background contribution that requires an accurate modeling in order to properly use X-ray photoelectron spectroscopy (XPS) as a quantitative technique. We obtained and analyzed XPS data of ultra-thin films of Co, Ni, Cu and Zn. Besides the photoemission lines and the background, the spectra contain satellite peaks and, in some cases, Auger lines that make the fitting procedure even more difficult. We used the full Tougaard1 background approach to determine the scattering contribution to the spectra and subsequently calculated the Shirley background component employing state of the art algorithms.2 We experimentally determine that the Shirley intensity is larger than the Tougaard component and that it depends on the chemical state of each chemical specie measured. It was very interesting to find that an accurate experimental data reproduction is only achieved by incorporating a Shirley component to the Tougaard background. 1. Tougaard, S. & Sigmund, P. Influence of elastic and inelastic scattering on energy spectra of electrons emitted from solids. Phys. Rev. B 25, 4452–4466 (1982). 2. Herrera-Gomez, A., Bravo-Sanchez, M., Ceballos-Sanchez, O. & Vazquez-Lepe, M. O. Practical methods for background subtraction in photoemission spectra. Surf. Interface Anal. (2014). doi:10.1002/sia.5453 150 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla INVITED TALK [ CHM-334 ] Raman scattering and infrared studies of graphite oxide platelets obtained from bamboo for electronic applications Jhon Jairo Prías Barragán ([email protected]) 3 , Jhon Jairo Prías Barragán ([email protected]) 2 , Katherine Gross 1 , Hernando Ariza Calderón 3 , Pedro Prieto Pulido 1 1 Center of Excellence for Novel Materials, Universidad del Valle, PO Box 25157, Cali, Colombia 2 Electronic Instrumentation Technology Program, Universidad del Quindío, PO Box 661, Armenia, Colombia 3 Interdisciplinary Institute of Sciences, Universidad del Quindío, Carrera 15 Calle 12 Norte, Postal Code 630001, Armenia, Colombia Graphite oxide is an interesting candidate for electronic applications; therefore, important efforts are dedicated to both large-scaled and low-cost graphite oxide production as an intermediate in graphene production. At the same time, research efforts are aimed at identifying the role of defects in the magneto-electrical properties of platelets for electronic applications. In this paper, we present a new low-cost fabrication process to obtain graphite oxide platelets of high crystal and thermo-electrical quality. The graphite oxide platelet samples were first obtained from bamboo pyroligneous acid (GO-BPA) by thermal decomposition method using a pyrolysis system for different carbonization temperatures from 673 to 973 K. The GO-BPA samples were characterized by using Raman, FTIR, XRD, and SEM techniques, whose results suggest that increased carbonization temperature increases graphite conversion, boundary defects, desorption of some organic compounds and phonon response, respectively. Finally, we discuss potential applications of the GO-BPA samples involving phonon response that would benefit from a fully scaled technology, advanced electronic sensors and devices 151 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ CHM-349 ] Implementation of the Z-scan technique using NI cRIO 9074 system Rubén Gutiérrez Fuentes ([email protected]) 1 , Rubén Gutiérrez Fuentes ([email protected]) 2 , Miguel Ángel Camacho López 1 1 Laboratorio de Fotomedicina, Biofotónica y Espectroscopia Láser de Pulsos Ultracortos, Facultad de Medicina, Universidad Autónoma del Estado de México, Jesús Carranza y Paseo Tollocan s/n, C.P. 50120, Toluca, México. 2 Universidad Politécnica del Valle de Toluca, Km 5.6 de la Carretera Toluca-Almoloya de Juárez, Santiaguito Tlalcilalcali, C.P. 50904, Almoloya de Juárez, México. In this work we show the implementation of Z-scan technique using NI cRIO 9074 system to characterize different types of nanofluids and films. This technique was mounted in the Facultad de Medicina of the Universidad Autonoma del Estado de Mexico. For this, a chassis NI cRIO9074 of National Instruments, a linear translation stage and a stepper motor controller BSC203, both of Thorlabs were used. Three steps were followed for the implementation of Z-scan technique. First, the connection between NI cRIO9074 and BSC203 controller was made. This connection went through of TTL trigger signals (5 volts). Second, it was the construction of algorithm and program on LabVIEW. Finally, the implementation of all optic part of the z-scan technique was made. This implementation can be used to characterize relatively thin (< 5mm) optical materials. The system testing was done with gold nanoparticles and a radiochromic film. The results show the nonlinear optical properties of these samples. The main advantages of using this system is the precision and spent minor time on measurements. 152 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ CHM-350 ] EFECT OF GEOMETRIC FACTORS IN DIFFERENTIAL CROSS SECTION Julio Heriberto Mata Salazar ([email protected]) 1 , Alberto Herrera Gómez ([email protected]) 1 1 Cinvestav, Unidad Querétaro. One of the main applications of X-ray photoelectron spectroscopy (XPS) is the assessment of the chemical composition of surfaces. In a previous work we discussed the inconsistencies, well beyond the experimental error, that take place when X-ray sources at different angles are employed [1]. That is, the surface composition assessed employing different sources are not consistent with each other. These inconsistencies might be due to a number of issues. We explored 1) the effect of the geometry of X-ray monochromator crystals on the effective differential cross sections, 2) the combined effect of the partial polarization caused by the monochromator [2] with elastic scattering on the effective attenuation length (EAL), and 3) the detailed dependence of the EAL with depth [2]. We concluded that these effect are well below the uncertainty on the peak intensities and that cannot explain the differences. Other options are being explored. Keywords: xps composition calculations, monochromatizer crystal geometry, electron effective attenuation length. References: [1] J.H. Mata-Salazar, A. Herrera-Gómez, “Angular dependence of photoelectric differential Cross Section”, VI International Conference on Surfaces, Materials and Vacuum (2013). [2] A. Herrera-Gomez, “Effect of monochromator X-ray Bragg reflection on photoelectric cross section”, Journal of Electron Spectroscopy and Related Phenomena 182 (2010) 81–83 [3] C.J. Powell, A. Jablonski, “Electron effective attenuation length for applications in Auger electronspectroscopy and x-ray photoelectron spectroscopy”, Surf. Interface Anal. 2002, Vol 33:211-229. 153 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ CHM-363 ] A pilot comparison in México. Determination of mass fraction of four copper gold alloys with EDS and WDS surface analysis techniques-. José Manuel Juárez García ([email protected]) 1 , José Antonio Salas Téllez 1 , Yoshito Mitani Nakanishi 1 , Hugo Rojas Chávez 3 , José Gerardo Cabañas Moreno 2 1 2 Centro Nacional de Metrología Centro de Investigación y de Estudios Avanzados del IPN 3 Instituto Tecnológico de Tláhuac II Has been performed a pilot comparison, having the national metrology center Mexico as organizer, the objective to compare fraction mass measurements with energy dispersive spectrometer (EDS) and wavelength dispersive spectrometer (WDS) for binary metal alloys containing copper and gold, the high energy Cu-K and Au-L lines at about 8 keV and 10 keV, respectively, were used for quantification. The pure copper and gold reference standards were also supplied to all participants in the pilot study. In this pilot comparison involved seventeen different microscopes with the techniques mentioned. The results will allow participating laboratories to know their measurement capabilities and the state of its accuracy, so they can take action to which in each case can improvement or refinement, also they may have information and knowledge to participate in a key comparison, which will be organized soon. 154 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ CHM-414 ] Measurement technique to characterize a MOS photoelectric converter José Guillermo Pérez Luna ([email protected]) 1 , Luis Armando Moreno Coria 1 , Salvador Alcántara Iniesta 2 , Antonio Esteban Jiménez González 3 , Joaquín Alvarado Pulido 2 1 Facultad de Ciencias de la Electrónica, Benemérita Universidad Autónoma de Puebla, Av. 14 sur y Av. Sn Claudio, Ciudad Universitaria, Puebla, Pue., México, CP 72560 2 Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Av. 14 sur y Av. Sn Claudio, Ciudad Universitaria, Puebla, Pue., México, CP 72560 3 Instituto de Energías Renovables, Universidad Nacional Autónoma de México, Priv. Xochicalco S/N, Temixco Mor., México, CP 62580 The development of an analog circuit to characterize a MOS photoelectric converter is presented. A photoelectric converter is a device that transforms light into electrical energy. The converter is a MOS structure that includes a silicon wafer and an aluminum grill. The silicon surface is separated from the grill by several concentric SiO2 circles. The silicon surface is the anode and the grill is the cathode. The grill permits that an external light can be applied on the silicon surface for electron emission. The measurement circuit is designed with two differential configuration made with operational amplifiers. This circuit also includes a voltage source, a load resistor and a capacitor. The load resistor is connected between the voltage source and the photoelectric converter. A specific capacitor is used as a second load for current variation. The voltage data for the I-V plot are obtained at the output of the differential configurations. One is for the current measurement and the other for the voltage measurement between the electrical leads of the photoelectric converter. The results show that it is possible to measure small currents (10 nA) between the leads of the photoelectric converter. A parametric study was made for different light intensities. 155 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ CHM-436 ] The photoemission spectra of fully oxidized Zn Gabriela Molar-Velazquez ([email protected]) 2 , Dagoberto Cabrera-German 2 , Wencel de la Cruz 1 , Gustavo Gomez-Sosa 2 , Julio Mata-Salazar 2 , Alberto Herrera-Gomez ([email protected]) 2 1 2 CNyN, UNAM. Ensenada, B.C, Mexico C.P. 22800 Materials, CINVESTAV-Unidad Queretaro. Queretaro, Mexico C.P. 76230 Most, if not that all, of the X-ray photoelectron Spectroscopy (XPS) analysis of Zn and ZnO reported in the literature are qualitative in nature [1,2,3,4,5]. Quantitative studies are mostly absent due to the difficulties inherent to the analysis of transition metal core levels. We found that a proper analysis requires the simultaneous treatment of both, 3/2 and ½, branches of the 2p core level. However, the complexity of the background prevents this type of analysis with the traditional methods. By employing the double-Lorentzian line-shape and the active background approach, we performed an analysis of the whole Zn 2p core level (both branches) for the fully oxidized case [6,7,8,9,10,11]. Surface and bulk plasmons were identified, at 17 and 18.5 eV from the main peak, in accordance with the data already reported by REELS [5] . The chemical compositions resulted in the stoichiometric expected values of ZnO. References: [1] J.H. Scofield. Hartree-Slater subshell photoionization cross-sections at 1254 and 1487 eV, Journal of Electron Spectroscopy and Related Phenomena, 8 (1976) 129-l 37. [2] Widder, Knupfer, Knauff and Fink. Plasmon behavior of Zn from electron-energy-loss spectroscopy. Physical Review B, 1997. [3] Biesenger, Lao, Gerson and Smart. Resolving surface chemical states in XPS Analysis of first row transition metals, oxides and hydroxides: Sc, Ti, V, Cu and Zn. Applied Surface Science. [4] http://xpssimplified.com/elements/zinc.php [5] “Plasmon excitation energies in ZnO, CdO and MgO”, Hengehold and Pedrotti; Journal of applied physics 47, 287, 1976. [6] A double Lorentzian shape for asymmetric photoelectron peaks. A. Herrera-Gomez. Internal Report. Cinvestav-Querétaro (2011). http://www.qro.cinvestav.mx/~aherrera/reportesInternos/doubleLorentzian.pdf [7] A. Herrera-Gomez M. Bravo-Sanchez O. Ceballos-Sanchez and M.O. Vazquez-Lepe. Practical Methods for Background Subtraction in Photoemission Spectra, Surface and Interface Analysis (on press) 156 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [8] A. Herrera-Gomez, M. Bravo-Sanchez, F.S. Aguirre-Tostado, M.O. Vazquez-Lepe. The slope-background for the near-peak regimen of photo emission spectra, Journal of Electron Spectroscopy and Related Phenomena 189 (2013) 76– 80. [9] Alberto Herrera-Gomez. The active background method in XPS data peak fitting, Internal Report (Created: 3/2011. Last Update: 9/2012). CINVESTAV- Queretaro. [10] Alberto Herrera-Gomez. The Peak-Shirley Background (Shirley background in overlapping peaks), Internal Report (Created: 8/2011. Last Update: 2/2012), CINVESTAVQueretaro. [11] M. Bravo Sanchez, M.O. Vazquez-Lepe, F. Espinosa-Magaña, A. Herrera-Gomez. Analysis of the Fe 2p spectrum employing the double Lorentzian asymmetric line-shape (submitted). [12] http://rdataa.com/aanalyzer/aanaHome.htm [ CHM-447 ] The photoemission spectra of metallic yttrium and its oxide. Víctor Arellano-Arreola ([email protected]) 1 , Gustavo GómezSosa 1 , Zeus Montiel-González 1 , Alberto Herrera-Gómez ([email protected]) 1 1 CINVESTAV Unidad Queretaro, Queretaro-76230, Mexico The traditional methods for peak-fitting X-ray photoelectron spectroscopy (XPS) data of transition metals and their oxides are clearly insufficient. The current methods cannot reproduce the complex plasmon losses, shake-up peaks, and, most importantly, high peakasymmetry present in those spectra. By employing state-of-the-art analysis methods it was possible properly fit the 3d spectra of metallic yttrium and a small amount of native oxide. Sublimation of metallic yttrium on Si (100) wafers was performed under vacuum. The angleresolved high resolution measurements were carried out employing a non-monochromatic Al (1486.7 eV) X-ray source and a hemispherical spectrometer with seven channeltrons. The base pressure of analysis chamber was 10−9 Torr during data acquisition. Peak fitting was performed using AAnalyzer®1 software, employing symmetric (Voigt) and asymmetric (double-Lorentzian2) line-shapes. In addition, a combination of Shirley–Proctor–Sherwood and slope backgrounds were employed using the active approach3. 157 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla The double-Lorentzian asymmetry factor of the Y 3d peak is 3.33 for both the metallic and oxide cases. The Y 3d5/2 component is located at a binding energy of 154.58 eV for the metal and at 157.31 eV for the native oxide. The composition was calculated employing the Multilayer Model, resulting in close agreement with the expected values of Y2O3.This is the first report known to the authors that addresses the composition of yttrium oxide from XPS data. References [1]http://www.rdataa.com/aanalyzer/aanaHome.htm. [2] A. Herrera-Gomez, A double Lorentzian shape for asymmetric photo-electron peaks, Internal Report, Cinvestav-Querétaro, 2011. http://www.qro.cinvestav.mx/∼aherrera/reportesInternos/doubleLorentzian.pdf [3] A. Herrera-Gomez, M. Bravo-Sanchez, F.S. Aguirre-Tostado, M.O.Vazquez-Lepe, J. Electron. Spectrosc. Relat. Phenom. 189 (2013) 76–80. 158 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ CHM-486 ] Study of the microstructural behavior of vanadium pentoxide modified with silver C. Rivera Rodríguez ([email protected]) 2 , F. Gonzalez-Zavala 3 , L. Escobar-Alarcón 3 , D. A. Solís-Casados 1 , E. Haro Poniatowski 4 1 Centro Conjunto de Investigación en Química Sustentable UAEM-UNAM, Carretera Toluca-Atlacomulco Km 14.5, Unidad San Cayetano, Toluca, Estado de México, 50200, México. 2 Departamento de Estudios del Ambiente, Instituto Nacional de Investigaciones Nucleares, Apdo. Postal 18-1027, México DF 11801, México. 3 Departamento de Física, Instituto Nacional de Investigaciones Nucleares, Apdo. Postal 18-1027, México DF 11801, México. 4 Departamento de Física. Universidad Autónoma Metropolitana Iztapalapa. San Rafael Atlixco No. 186, Col. Vicentina, Iztapalapa, 09340, México. Due to their different oxidation states, from V2+ to V5+, Vanadium form a broad variety of impressive structural arrangements as a result of its coordination with oxygen, which provides exceptional physical and chemical surface properties, such as: high thermal stability and high mechanical strength, so it is required in selective oxidation-reduction processes, in the manufacture of certain important chemicals and mainly in reducing environmental pollutants. This work shows results about the structural modifications of V2O5 through the incorporation of different amounts of silver. The synthesis procedure is performed of direct form by combining vanadium pentoxide with silver nitrate (NHAg) powdered; the obtained mixtures were subsequently thermally treated at 500°C during one hour in normal atmosphere. Through measurements carried out by EDS, the obtained materials showed a gradual increase in silver content ranging from 3.6 to 26.8 at. %, while the vanadium present in the mixtures decreases from 37.6 to 7.2 at. %. Studies through XRD and Raman spectroscopy reveal that silver is incorporated into the structure of V2O5 resulting different crystalline phases, Ag0.4V2O5, Ag1.2(V3O8), Ag0.4V2O5, AgVO3, Ag(VO3), reaching the composition of Ag4V2O7, with certain amounts of V2O9 and segregates in the form of silver oxide (AgO) and pure Ag. The obtained compounds could have potential applications as photocatalysis in the degradation of organic compounds dissolved in waste waters. 159 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ CHM-546 ] Analysis of the Formation of Iron Oxides on Surfaces of Gray Iron Cast Applying Diffuse Reflectance Spectroscopy Catalina Melo Piquive ([email protected]) 1 , Oscar Edwin Piamba Tulcan 1 1 Universidad Nacional de Colombia The gray iron cast surfaces are submitted to a high index of corrosion in the exposition with different environmental substances due mainly to the formation of iron oxides such as goethite, hematite, maghemite, and lepidocrocite, causing a deterioration in the mechanical properties of these materials. The characterization of corrosion products on surfaces of materials that are expose to different conditions of operation, demand the development of a technique inexpensive, fast and portable. This work describes the optical reflectance technique that has been developed to the study of this corrosion products. Specially, this technique will allow the identification of the presence of iron oxides in situ, is a fast and inexpensive tool and environmentally friendly procedure that could be an alternative to the conventional surfaces analysis method. The diffuse reflectance spectrum in the visible and infrared regions (Vis/NIR, 400-2500nm) were recorded and studied to assess the spectral dependence of these oxides, predict their relationship and thereby identify it. The agreement with the experimental results show that the diffuse reflectance spectroscopy could be a helpful method of quantifying of iron oxides on surfaces. 160 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla Sesión Poster [ CHM-11 ] Determination of the Parameters of the Bergman´s Model for Diabetic Mice Treated with Ibervillea sonorae Agustín Ignacio Cabrera Llanos ([email protected]) 1 , Artemio Alejandro Sotelo de Ávila 1 , Omar Itzamna Rico Ascensión 1 , Emmanuel Sánchez Velarde 1 , María Guadalupe Ramírez Sotelo 1 , Rodrigo Sánchez González 1 1 UPIBI-IPN In this paper the estimation of model parameters Bergman for glucose-insulin interaction in three states is presented. Besides glucose dynamics in diabetic mice treated with Ibervillea sonorae extracts in a range of 100-400 mg / kg. Likewise, the estimate is shown for healthy mice and different parameter values obtained are compared showing how these influence the dynamics of Bergman´s model. Evolution and variability of the estimate is shown in graphical form, also, the estimation error is quantified by curves of a quadratic performance index. The results indicate that the estimated level was reached. [ CHM-12 ] Portable Measuring System Performance in Athletic Aerobic Phase Synchronization Visual Platform with LabVIEW and ATmega Controllers Emmanuel Sánchez Velarde ([email protected]) 1 , Agustín Ignacio Cabrera Llanos ([email protected]) 1 , Omar Itzamna Rico Ascensión 1 , María Guadalupe Ramirez Sotelo 1 , Artemio Alejandro Sotelo de Ávila 1 1 UPIBI-IPN In this work, a remote monitoring system for measuring heart rate and deployment of an ECG signal is presented. This system uses a pulse sensor plug-and-play type placed on the lobe of the patient to obtain a signal, which is represented by squares; each symmetric pulse width 161 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla is the width of the plethysmographic signal obtained by the sensor. And, an electrocardiograph developed for obtaining a derivative (positive, negative, and reference electrode), a filtering step to obtain the complete signal through the basic vector comprising Eithoven triangle. Both signals were transmitted via a ZigBee protocol radio frequency, using two Xbee modules series S1, data were received through a ATMEGA328P, later, by the LabVIEW platform, and anthropometric data of the individual, to monitor the heart rate, continued deployment of the 2 signals obtained presented along a routine of aerobic exercise and a history of heart and indicator signal obtained this in order to observe their status. A series of measurements of heart rate and ECG signal for individuals undergoing physical activity of different intensity is presented. [ CHM-167 ] Spectroscopic analysis of Er 3+ ion doped sodium chloride crystals Daniel Enrique Huerta Figueroa ([email protected]) 1 , Rebeca Sosa Fonseca 2 1 Physics Departement Universidad Autónoma Metropolitana- Iztapalapa, Distrito Federal, México PO BOX 55-532 2 Physics Departement Universidad Autónoma Metropolitana- Iztapalapa, Distrito Federal, México PO BOX 55-532. Photoluminescence analysis of trivalent erbium ion introduced in NaCl monocrystalline, are presented. NaCl crystals doped with low concentrations of Er3+ ions were grow by Bridgman technique with molar per cent concentrations of 0.005%, 0.05%, 1% and 2%, respectively. Measurements of absorption, emission and excitation spectra of as grown NaCl: Er3+ crystals were made at room temperature, respectively. The optical response of the lower concentrations sample is so weak, but the 1% mol sample was the best. Any case it was possible identify the typical transitions of erbium ion from the base state 4I15/2 to several multiplets due to 4fN configurations. X-Ray pattern show a crystal structure in all the samples. 162 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ CHM-175 ] Design and construction a four-point method system for electrical characterization of thin films with photovoltaic applications Julio César Estrella Rodríguez ([email protected]) 1 , Fabio Chalé Lara 1 , Felipe Caballero Briones 1 , González Prieto Dalia Itzel 2 , Óscar Márquez González 2 , Allan Herrera Eusebio 2 1 Instituto Politécnico Nacional, Laboratorio de Materiales Fotovoltaicos, CICATA Altamira, Km 14,5 Carretera Tampico-Puerto Industrial Altamira, Altamira, México 2 Universidad Tecnológica de Altamira, Blvd. de los Ríos Km. 3+100, Puerto Industrial, 89603 Altamira, Tamaulipas We present a system for measuring the sheet resistance by the four point method in semiconductor thin films. The system includes: a sample holder, a head holder probes, two electrometers Keithley Model 6517B of high impedance, a current source Keithley 6221 and a multimeter Keithley model 2000, all connected to a computer through a GPIB interface.For calculating the sheet resistance of thin films, the Van Der Pauw method was used. Electrical measurements were performed in darkness and light. As a light source of a halogen lamp 50 watts and a wavelength ranging from 300 to 800 nanometers it is used.The measurement involves placing the sample in the sample holder, placed above the tip holder and verify that the tips are in contact with the thin film, the computer program in a sweep current supplied by the power amperage through two points which fence in the ranges for the deposited semiconductor material and obtain a voltage at one end of each electrometer finally measuring the potential difference between both the voltmeter and registering in a database on the computer.IV curves were performed for CdS:Mg and ZnO:Al thin films. Chemical Bath Deposition and Spray Pyrolysis methods were employed to deposit thin films on glass substrates. The behavior of metal and semiconductor junction is present in all thin films, and there is a growing exponential increase in the measured voltage for current applied. For CdS:Mg thin films values of sheet resistance was observed that the tendency of resistance decreasing between 1 GΩ to 100 MΩ applying light on thin films. Resistance in ZnO:Al films was in 1 to 5 MΩ. This work is supported by SIP-IPN 20150599 project. 163 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ CHM-187 ] Photoluminescence and EDS studies of Er3+ ions incorporated in a SiO2 matrix by sol-gel method M. Gómez-Miranda ([email protected]) 1 , C. Velásquez Ordoñez 2 , R. Sosa Fonseca 1 1 Physics Department Universidad Autónoma Metropolitana. Iztapalapa. PO Box 55-532. México, D.F. 2 Research Center of Nanoscience and Nanotechnology at Universidad de Guadalajara Centro Universitario de los Valles. Ameca Jal. México Transparent gels of SiO2 :Er3+ were synthesized and homogeneous sample was obtained by sol-gel method. Absorption, emission spectra and EDS characterized the final monolith. By spectroscopic measurements it was possible identify the typical transitions of erbium ion from the base state 4I15/2 to several multiplets due to 4fn configurations, namely 2H9/2 → 4I15/2, 4F 4 4 4 2 4 2 4 2 4 5/2 → I15/2, S3/2 → I15/2, P3/2 → F9/2, H9/2 → I11/2, P3/2 → S3/2. Some quantities were obtained from absorption and emission spectra to make the diagram level of Er3+ ion in SiO2 matrix. It is adjusted the absorption spectrum data with a deconvolution method in Gaussian bands to find the areas under the curve, for a qualitative analysis of the relative intensities each transition. EDS results give information about the homogeneity and the composition of SiO2:Er3+. The emission spectra show several transitions of Er3+, particularly the 516 nm that is a reabsorption band and that means that there is an optical interaction between the ion-host. In this sense, trivalent erbium ion is used as activator in the host lattice to improve the phosphorescence intensity. 164 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ CHM-219 ] Synthesis of Tm3+:Y2O3 phosphors using benzyl alcohol route by microwave-assisted technique Jose Antonio Luna Guzman ([email protected]) 1 , Gilberto Alarcon Flores 1 , Miguel Angel Aguilar Frutis 1 , Martha Patricia Campos Arias 1 , Salvador Carmona Tellez 2 , Ciro Falcony 2 , Manuel Garcia Hipolito 3 , Raul Ivan Sanchez Alarcon 1 1 Departamento de Fisico Quimica, Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada del Instituto Politécnico Nacional, Legaría 694. Colonia Irrigación, 11500 México DF 2 Departamento de Física, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Av. Instituto Politécnico Nacional 2508, Col. San Pedro Zacatenco, Delegación Gustavo A. Madero CP 0736, México D.F. 3 Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Del. Coyoacán, CP 04150 México DF. In this work we present results about the synthesis and characterization of Tm3+:Y2O3 phosphors prepared by the Microwave-Assisted route, usingbenzyl alcohol. The MicrowaveAssisted technique is able to allow a rapid heating to reach the required temperature of synthesis and it has the advantage to probe the pressure during the reaction. These features makes the Microwave assisted technique a very controllable, reproducible and potential method to synthesize different materials and nanomaterials. In this research, Tm3+:Y2O3benzoate hybrid organic–inorganic nanocomposites were obtained at 270 °C. The nanophosphors as synthesized showed an emission band between 420 nm and 500 nm. In that spectra the most intense peaks were located at wavelengths of 455 nm, which belong to the 1D2→3F4 transition of trivalent Thulium, as well as a complete structural characterization by Electron Microscopy, X-ray Diffraction, and Energy Dispersive Spectroscopy (EDS). The authors acknowledge the financial aid to carry out this work to Secretaría de Investigación y Posgradodel INSTITUTO POLITECNICO NACIONAL, grant # 2015 1155 and 2015-1093 and BEIFI-IPN Program. 165 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ CHM-237 ] Study of the optical properties of porous silicon with different processes Maricela Meneses Meneses ([email protected]) 1 , José Alberto Luna López ([email protected]) 1 , Estela Gómez Barojas 1 , José Francisco Flores Gracia 1 , David Hernández de la Luz 1 , Miguel Ángel Domínguez Jiménez 1 1 CIDS-IC, BUAP. Edf. 103-C, C.U. Puebla, Pue. 72000, Mexico. Porous silicon (PS) shows interesting optical and electrical properties that can be used in devices such as: photodetectors, gas sensors, biosensors, solar cells among others; but is necessary to stabilize the PS to be compatible with the crystalline silicon (c-Si) technology. The objective of this work is to study the influence of the thickness of the PS layers after the application of several processes such as dry oxidation (DO), thermal treatment (TT) and infiltration with organic molecules (FO), specifically sodium fluorescein. PS single layers were obtained by electrochemical etching of silicon wafers ptype with orientation (100) and a resistivity 0.01-0.02 Ω•cm, in an electrochemical cell with two electrodes. The electrolyte solution contains: Ethanol: HF: glycerol, anodization solution was kept constant for all processes. The current density was of J = 22 mA/cm2, anodizing times were: 30, 60, 120, 240 and 1200 s. Process such as TT and/or DO and/or FO with sodium fluorescein at a concentration of 2.4 mM were applied a these PS single layers for comparison . The percentage of porosity (% P) of the first set of PS single layers was realized by the gravimetric technique and the refractive index (n) was calculated by using the effective medium approximation with the Bruggeman´s formula. The optical properties of all PS-layers series were characterized after each process using the spectroscopy techniques: UV-Vis-NIR, fluorescence and μ-Raman. The thicknesses (0.25, 0.50, 1, 2 and 10 µm) of the single layers for the first PS set were measured with a profilometer. The fluorescence of PS single layers with TT, DO and FO increases related with the PS single layers without any process, and there is a shift to lower wavelengths. The reflectance percentage of PS single layers with TT, DO and FO decreases and Raman spectra show a small peak broadening with the same position for the c-Si. Keywords: PS, FS, electrochemical anodization, fluorescence, reflectance. ACKNOWLEDGMENT This work has been partially supported by projects CONACyT-154725, PROFOCIE and VIEPLULJ-EXC15-G. The authors acknowledge IFUAP, INAOE and CIDS laboratory for their help in the samples measurements. email: [email protected] Referencias: [1] L. Pavesi. Revista del Nuovo [2] M.A. Lambert, Rep. Prog. Phys. 27(1964), 329. Cimento. 20, 10(1997), 1-20. 166 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ CHM-243 ] Micromorphology and evaluating mechanical properties of the dentin-resin interface of fluorotic teeth conditioning with different bonding techniques Ana Josefina Monjarás Ávila 1 , Norma Verónica Zavala Alonso 1 , Gabriel Alejandro Martínez Castañón 1 , Nuria Patiño Marín 1 , Facundo Ruíz 2 1 Doctorado en Ciencias Odontológicas, Facultad de Estomatología, UASLP, Av. Dr. Manuel Nava No. 2, Zona Universitaria, San Luis Potosí, S.L.P., México, C.P. 78290 2 Doctorado en Ciencias, Facultad de Ciencias Introduction: In response to the effects of fluorosis in the enamel, dentin shows hypermineralization. Because of this and the composition of dentin, adhesive restorations retention difficult. Recurrent caries in teeth restoration is the main reason for failure. Antibacterial agents uncured adhesive systems, can flow in the dentinal tubules and remove residual bacteria in the tooth cavity, particularly beneficial in the formation of marginal microintervals. Objective: To evaluate the micromorphology and mechanical properties of the dentin-resin interface of fluorotic teeth conditioning with different bonding techniques. Materials and Methods: After dental organs extracted by periodontal disease, healthy and with different degrees of fluorosis, classified according to Dean index were obtained. Bond strength to dentin-resin interface of fluorotic teeth was evaluated by testing microtensile in Universal Testing Machine, applying the conventional technique using an etching system (OptiBond Versa) Deproteinization (5.25% NaOCl for 1 min. ) and silver nanoparticles (NaAg) and then the resin (Filtek Z250 3M) was placed, photocuring 20 seconds in increments of 2mm, subsequently the failure mode (adhesive, cohesive, mixed) through the stereomicroscope was observed, and the resin-dentin interface of fluorotic teeth through Scanning Electron Microscope each study group analyzed the different bonding techniques. Averages, standard deviations and ranges of quantitative variables were calculated. Results: The adhesion in the group of healthy dentin and dentin with mild fluorosis is benefited with conventional adhesion technique unlike the group with moderate fluorois dentin, where the adhesion strength is benefit when was applied deproteinisation technique and NaAg. Adhesive failure was the most presented, followed by cohesive failure. In the microphotographs continuous dentin-resin interface was observed with the three bonding techniques in all study groups. Conclusion: Were obtained adhesives satisfactory results in the three study groups, microscopic signs of the interface, suggesting that the chemical bond with hydroxyapatite crystals remaining in the partially demineralized smear layer, may have a role in the binding mechanism of these adhesives of last generation. 167 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ CHM-251 ] Intermetallic phases of Fe-Al formed in the aluminized steels obtained by hot dip technique Bárbara Hernández-Hidalgo 1 , Cesar Castelán-Acevedo 1 , Bertha S. Zalazar-Ramírez ([email protected]) 1 , Roberto T. Hernández L. ([email protected]) 1 1 Departamento de Materiales, UAM-Azcapotzalco, Av. San Pablo 180, ReynosaTamaulipas, Azcapotzalco, México D.F., C.P. 02200 In various steel applications in corrosive environments, process or treatments are required to reduce or inhibit spoilage. For this purpose, surface layers composed of metals and other materials are been using, among these the aluminized, obtained by hot dip is employee intensively. This process involves immersing the metallic specimen in aluminum at temperatures above its melting temperature. Metals remain in the liquid by certain times. In this paper, hot dip process are used for obtain a aluminum layer on the steels AISI-SAE 1045, 4140 and 8620. The objective is provides a surface hardness more high, good ductility inside and good corrosion resistant. Samples of steel bars of varying diameter and 6cm length slowly immersed in molten Al which is at temperature of 810 ° C and by times of 8 to 40 min of stay. For each steel optic and electronic microscopy photomicrographs are performed. The images show that depending of the steel and the different stay times, in each samples are formed two or three regions of phase different between the steel inner and outer layer of Al. The thickness of the regions depends on the residence time of the steel samples. Studies of chemical composition (EDS) and X-ray diffraction indicated that each of these regions is constituted by a single phase intermetallic Fe-Al. 168 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ CHM-258 ] Characterization of intermetallic compounds in Zn and Zn-18%Cu coatings on the 8620 steel obtained by hot dip Ivan Caballero-Contreras 1 , Bertha S. Zalazar-Ramírez 1 , Roberto T. Hernández L. ([email protected]) 1 1 Departamento de Materiales, UAM-Azcapotzalco, Av. San Pablo 180, ReynosaTamaulipas, Azcapotzalco, México D.F., C.P. 02200 The 8620 steel, besides iron and carbon, contains nickel, chromium and molybdenum. Has high values of surface hardness, good toughness in the core and is corrosion resistant. The steel is classified as machinery grade. In order to increase these properties it is proposed to cover it with a Zn coating or a alloy coating of Zn-18%Cu composition both obtained by the hot dip process. Steel rods of 1inch of diameter and 6cm long, perfectly clean, is slowly immersed in molten zinc at a temperature of 650 ° C and held within of 10 to 40 minutes. The surface area characterization by optical and electronic microscopy shows the formation of two or three layers between Zn and steel depending on the time of stay. Due to immersion in the alloy, two layers between Zn-18%Cu and the steel are observed. In each case the layers correspond to intermetallic compounds Zn-Fe for first case and Zn-Cu-Fe in the second. These layers are result of the diffusion from the surface to steel inwards of the atoms of Zn and Cu and their chemical reactions with Fe. In order to identify these intermetallic phases, chemical composition studies (EDS) and X-ray diffraction Microhardness measurements are made on the obtained surface layer and in each intermetallic area are also presented. [ CHM-259 ] XPS study of the Ag 3d spectrum David Salvador García-Zaleta ([email protected]) 1 , Gustavo Gómez-Sosa 1 , Alberto Herrera-Gómez ([email protected]) 1 1 LPCN, CINVESTAV-U. Querétaro X-ray photoelectron spectroscopy (XPS) is an important technique to analyze and characterize the surface of different types of materials such as metals, semiconductors, polymers, ceramics, etc. However, in many cases the various contributions to the total XPS signal overlap hiding relevant information. On the other hand, the current methods to analyze XPS data of transition metals and their oxides are clearly insufficient due to complex plasmon losses, shake-up peaks, large background intensity and large peak asymmetries. In this work, 169 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla Ag films were growth on Si (100) wafers using the sublimation method inside a high vacuum chamber. The films were characterized by the XPS technique. The data was analyzed considering the branches Ag 3d5/2 and Ag 3d3/2 as well as the (asymmetric) double-Lorentzian line-shape [1] in order to identify all the possible contributions. The asymmetry of the peak was measured, including the uncertainty on its value. References [1] A. Herrera-Gomez. A double Lorentzian shape for asymmetric photoelectron peaks. Internal Report. Cinvestav-Querétaro (2011). http://www.qro.cinvestav.mx/~aherrera/reportesInternos/doubleLorentzian.pdf [ CHM-265 ] Analysis temperature on the tire tread Marco Antonio Vázquez Chávez ([email protected]) 1 , Marco Antono Cruz Gómez ([email protected]) 1 , Edgar Iram Villagrán Arrollo 1 , Enrique Buendia Lozada 1 1 Benemérita Universidad Autónoma de Puebla This research aims to analyze the temperature on the surface of the tire tread in contact with concrete roadways. The characterization of the tread was made with: SEM, EDS, nanoindentation, AFM and thermography. The tests were carried out in trucks of public passenger transport in Puebla México for 12 Km route at average speed of 60 km/h with detail for ascent and descent of passengers. The results shows that the grooves areas had the highest temperature in the tread by presenting thermal cracks and loss of rubber elasticity. Keywords: tire, temperature, tread, thermal cracks 170 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ CHM-268 ] The photoemission spectra of Ru(0) and Ru(IV) nanoparticles Gustavo Gomez-Sosa ([email protected]) 2 , Nidia Garcia-Peña 1 , Rocio Redon 1 , Mariela Bravo-Sanchez 2 , Alberto Herrera-Gomez ([email protected]) 2 1 2 CCADET-UNAM CINVESTAV Queretaro A recent report1 has been published regarding the synthesis of Ru(0) and Ru(IV) nanoparticles employing low amounts of solvents. We performed X-Ray Photoelectron Spectroscopy (XPS) analysis to identify oxidation states of these materials. Ru nanoparticle was prepared by a mechanochemical method consisting of milling RuCl3·nH2O and BH4 in an agate mortar for 5 min, then washed with an small amount of water and ethanol and dried into an oven. The powder was compressed against an indium foil and mounted into a sample holder, all inside a glove box custom-coupled to the XPS load lock chamber. The sample handling was done under a high purity nitrogen atmosphere, as these nanoparticles react violently with ambient oxygen. The high resolution measurements were carried out employing a monochromatic Al K (1486.7 eV) X-ray source and a hemispherical spectrometer with seven channeltrons. Base pressure of analysis chamber was 10−9 Torr for data acquisition. Pass energy was 10 eV for high resolution spectra. Peak fitting was performed using AAnalyzer software, employing a Voigt profile2. The asymmetric peak corresponds to a double-Lorentzian line-shape3. Also, a combination of Shirley–Proctor– Sherwood and slope backgrounds were employed using the active approach4. Since the processing of the nanoparticles was done in the presence of oxygen, it was at expected that the ruthenium was going to be found in an oxidized state. Surprisingly, the XPS data clearly showed the presence of only Ru(0), without any detectable Ru2+ or Ru4+. As an additional test, the nanoparticles were subjected to thermal oxidation, heating at 850 ºC for 20 h in the presence of molecular oxygen to force the presence of oxides. Two evident contributions were observed, a doublet at 279.11 and 283.40 eV corresponding to Ru(0), and a second doublet with a binding energy about 1.7 eV higher, which can be attributed to Ru(IV). This doublet is consistent with the spectra of Ru(IV) nanoparticles processed by colloidal and solvothermal methods, consisting of large amounts of solvents under air atmosphere, alternated with washings and drying under vaccum . A detailed analysis of the Ru(0) and Ru(IV) is presented. References 171 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [1] N.G. Garcia-Peña, R. Redon, A. Herrera-Gomez, A.L. Fernandez-Osorio, M. BravoSanchez, G. Gómez-Sosa, Solventless synthesis of ruthenium nanoparticles, Applied Surface Science (2015) 340, 25-34 [2] http://www.rdataa.com/aanalyzer/aanaHome.htm. [3] A. Herrera-Gomez, A double Lorentzian shape for asymmetric photo-electron peaks, Internal Report, Cinvestav-Querétaro, 2011. http://www.qro.cinvestav.mx/∼aherrera/reportesInternos/doubleLorentzian.pdf [4] A. Herrera-Gomez, M. Bravo-Sanchez, F.S. Aguirre-Tostado, M.O.Vazquez-Lepe, J. Electron. Spectrosc. Relat. Phenom. 189 (2013) 76–80. [ CHM-301 ] Effect of process control agent during highenergy milling: a critical balance between cold welding and fracture H. Rojas-Chávez ([email protected]) 4 , D.A. Mora-Alvarado ([email protected]) 4 , J.A. Andraca-Adame 2 , M.L. Mondragón-Sánchez 3 , J.M. Juárez-García 5 , D. Jaramillo-Vigueras 1 1 2 Centro de Investigación e Innovación Tecnológica - IPN Centro de Nanociencias y Micro y Nanotecnologías - IPN 3 Instituto Tecnológico de Morelia - TecNM 4 Instituto Tecnológico de Tláhuac II - TecNM 5 Laboratorio de Microanálisis - CENAM In the case of Pb–Sn (ductile–ductile) system, it is difficult to use the high-energy milling (HEM) technique owing to stress, strain and recovery may occur almost simultaneously during milling, in other words, an excessive cold welding takes place. In such case, HEMprocess results in agglomeration of the as-milled raw materials, this in turn suppresses the mechanosynthesis. The nature of the ductile–ductile system is strictly related to its nature to store energy, as expected from its ability to generate and annihilate structural defects. During HEM-process heavy plastic deformation induces a high density of crystalline defects, such as: dislocations, stacking faults, grain boundaries effects, vacancies, and so on. All these defects enhance short-range mass transfer (diffusion) between precursors. Owing to the high volatility of CH3-CH2-OH (C2H6O) near to room temperature, it can effectively reduce coarsening and agglomeration during HEM-process. As a liquid, ethanol is embedded and finely distributed among the powders’ surface. However, one should expect that ethanol works as a solid–liquid reaction to helps in alleviating the tendency of ductile powder particles towards powder-to-ball/vial cold welding. 172 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla The Pb–Sn system is susceptible to hydrogen embrittlement. It is expected that the mechanism of hydrogen embrittlement for Pb–Sn system is that the high energy impacts (milling media) on the powders’ surface decompose ethanol embedded. As a consequence, H2 molecule and H atoms are obtained, and then atomic hydrogen diffuses into crystalline defects induced during HEM-process. Ethanol, as a process control agent (PCA), is used to achieve the critical balance between cold welding and fracturing, and enhance the HEM-process efficiency. Thus, a study into the effect of PCA on solid–liquid, solid–solid and solid–gas reactions ball milling is necessary and important. XRD and SEM results indicate that C2H6O as PCA showed anti-adhesive properties during HEM-process. The particle size, powder output and purity of the product depend on the properties of the PCA. Moreover, the PCA is not only able to decrease bonding and agglomeration, but can also accelerate the reaction to some extent. [ CHM-307 ] Monitoring the kinetics of formation of aggregates in ionic solutions by light scattering Oscar Ivan Pérez-San-Martín ([email protected]) 1 , Narcizo Muñoz-Aguirre ([email protected]) 1 1 Instituto Politécnico Nacional, Sección de Estudios de Posgrado e Investigación, Escuela Superior de Ingeniería Mecánica y Eléctrica-UA. Av. Granjas, N° 682, Colonia Santa Catarina. Del. Azcapotzalco, CP. 02250, México, D.F. México In this work the study the scattering of visible light through ionic solutions is presented. One of the specific objectives of this study is to measure particles whose size is below of the micrometer scale. Light transmission spectra as a function of time and using a wavelength range of 400 to 800 nm were considered. Analysis in pure water and solutions such as salt water and water polystyrene particles at different temperatures is presented. For taken into account factors as the solute employed and the temperature at which the measurement is performed, an experimental set up which facilitate the incorporation of the solution and adjusting the optical fibers of components measuring a portable spectrometer was designed. A theoretical model of particle agglomeration based on the Tindall effect is proposed. References 173 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla E. López-Sandoval, C. Vázquez-López, B.E. Zendejas-Leal, G. Ramos, E. San MartínMartínez, N. Muñoz-Aguirre, and E. Reguera “Calcium carbonate scale inhibition using the “allotropic cell” device”, Desalination 217, 85-92 (2007).ISSN: 0011-9164. Work partially supported by Instituto Politécnico Nacional from México with the project number SIP-20151005. [ CHM-309 ] Textural and microstructural properties of SBA-15 for removal of pharmaceuticals from wastewater. Martha Chico Vázquez ([email protected]) 1 , Mónica Rosalía Jaime Fonseca 1 , Patricia Rayo Mayoral 2 1 Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada IPN 2 Instituto Mexicano del Petróleo Recently, pollution of pharmaceuticals in water is an environmental concern. Unknown chronic ecotoxicities effects together with antibiotic resistance issue are making increasingly anxieties due to wide spreads of pharmaceuticals. The current technologies used in water treatment systems are not effective enough to eliminate many pharmaceuticals. Therefore, treatment technologies that achieve effective pharmaceutical removal need to be developed [1]. Among several technologies proposed for the removal of pharmaceuticals from water, for example, nanofiltration, advanced oxidation processes, and adsorption. Adsorption has been receiving special attention owing to its simplicity, low setup and operation cost, and no production of undesirable by products. Several studies have evaluated the adsorption of pharmaceuticals on zeolites, activated carbón, montmorillonite, and mesoporous silica. Among them, mesoporous silica with high surface area, large and uniform pore size, high pore volume, and tailorable surface can be good candidates for the adsorptive removal of pharmaceuticals [2]. In this study, SBA-15 (mesoporous silica), was synthesized using the method reported by Zhao [3]. Whit this method, a reproducible mesoporous material with a surface area of 745 m2/g, pore size of 8.6 nm, particle size 1.2 m, hexagonal structure with symmetry p6mm (confirmed by XRD and TEM) was obtained. 174 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ CHM-310 ] Nonlinear Refractive Index Coefficient of Cadmium Sulfide Nanoparticles Obtained by Z-scan Technique Yolanda Elinor Bravo-García ([email protected]) 2 , Patricia Rodríguez-Fragoso 3 , Edmundo Reynoso-Lara 2 , José Antonio DávilaPintle 2 , José Alberto Andraca-Adame 1 , Gerardo González de la Cruz 3 , Julio Gregorio Mendoza-Álvarez 3 , Orlando Zelaya-Angel 3 1 CNMN-IPN FCE-BUAP 3 Physics Department-CINVESTAV 2 Z-scan technique is a simple method to obtain both refractive and absorption nonlinear coefficients. It consist in to scan a sample in a focused beam to measure the transmittance to far field. In the photodetector there is an aperture to detect only on-axis intensity. The data plotted of transmittance vs position is the so called z-scan curve. There are many models to reproduce these curves, here we used the photoinduced focal length model (PFL). It considers to the sample as a lens with a dependence of beam radius powered to integer number m. Depending of the value of m is the physical phenomenon that determines the nature of the nonlinear optics property. Semiconductor nanoparticles CdS with uniform size were prepared using different passivating agents in aqueous solution with various pH. A cw HeNe laser was used in the wavelength of 632 nm with different powers. The nanoparticles exhibit both positive and negative nonlinearities whose amplitude depends on the pH. 175 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ CHM-312 ] Development of a fiber optic Surface Plasmon Resonance sensor using gold nano-spheroids Víctor Manuel Canchola-Flores ([email protected]) 1 , Narcizo Muñoz-Aguirre ([email protected]) 1 1 Instituto Politécnico Nacional, Sección de Estudios de Posgrado e Investigación, Escuela Superior de Ingeniería Mecánica y Eléctrica-UA. Av. Granjas, N° 682, Colonia Santa Catarina. Del. Azcapotzalco, CP. 02250, México, D.F. México Surface plasmon resonance sensor which employs gold nano-spheroids deposited on a fiber optic cross section was developed. For their structural characterization, gold nano-spheroids were formed from a gold thin film deposited on glass substrates by an electron beam evaporation system after the thermal treatments at 500, 600 and 700 °C. AFM images showed longitudinal axes of average sizes of 40 nm to 80 nm in spheroids geometries showing changes as the annealing temperature increases. The UV-VIS spectra showed surface plasmon resonances shifts when the fiber optic interacts with a fluid as showing by Fabrice Meriaudeau et. al. [1] and N. Muñoz-Aguirre et. al. [2] for gold particles supported on glass. It was also confirmed that the resonances frequency positions depends on the size and shape of the nano-spheroids. References: [1] F. Meriaudeau, A. Wig, A. Passian, T. Downey, M. Buncick, T.L. Ferrell, Gold island fiber optic sensor for refractive index sensing, Sens. Actuators B 69 (2000) 51–57. [2] N. Muñoz-Aguirre, A. Passian, L. Martínez Pérez, E. López-Sandoval, C. VázquezLópez, J. L. Jiménez-Pérez and T.L. Ferrell. The use of the surface plasmons resonance sensor in the study of the influence of “allotropic” cells on water. Sens. Actuators B 2004, 99, 149-155. Work partially supported by Instituto Politécnico Nacional from México with the project number SIP-20151005. 176 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ CHM-339 ] Characterization of amorphous ribbons by magnetoimpedance tecnique. Andrés Rosales ([email protected]) 1 , Diego Gómez 1 , Fabio Saccone 2 1 Universidad Nacional de Colombia Sede Manizales 2 Universidad de Buenos Aires The study of magnetic and electrical properties of materials has influenced the technological development of societies. In this context, properties such as impedance, reactance, susceptance, the quality factor, among others, make these materials be useful to industrial and medical purposes. Soft magnetic materials that exhibit giant magnetoimpedance MIG, have been studied intensively. It has been determined its impedance in the magnetic field for different frequencies, however, other characteristics such as its susceptance and quality factor have not been studied yet, and those are important parameters that characterize them for their technological applications. In this work we adapted a system for measuring the above parameters, which has been applied to study different materials. Also discussed the different characteristics of the developed system to parameters such as frequency and applied magnetic field variations in the samples. [ CHM-343 ] A new satellite found on manganese spectra Cynthia-Iveth Negrete-Martinez ([email protected]) 1 , Gustavo Gomez-Sosa 1 , Julio-Heriberto Mata-Salazar 1 , Dagoberto CabreraGerman 1 , Alberto Herrera-Gomez ([email protected]) 1 1 CINVESTAV -Unidad Querétaro. Queretaro, 76230 Mexico A shake-up satellite was found in manganese spectra obtained by X-ray photoelectron spectroscopy. Manganese was evaporated on a Si (001) wafer in a high vacuum chamber employing a tungsten filament. To discriminate the satellite from an oxide peak, the early stages of oxidation were studied in detail. The oxidation was carried out at room temperature with three oxygen exposures (4L, 44L and 400L). The curve fitting of the main peaks (Mn 2p, Mn 3p, Mn 3s, O 1s and C 1s) was done employing the double-Lorentzian assymmetric line shape [1] and the active background approach [2, 3]. In addition to the novel peak fitting, which resulted in a close reproduction of the experimental data, the analysis revealed the presence of a shake-up satellite which has not been reported in literature. 177 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla Keywords: Shake-up satellite, Double-Lorentzian, Active Background. Acknowledgements: This work was supported in part by CONACyT Projects INFR-201101 #163219 and CB-2012-01 #179304. [1] A double Lorentzian shape for asymmetric photoelectron peaks. A. Herrera- Gomez. Internal Report. Cinvestav-Queretaro (2011). http:// www.qro.cinvestav.mx/ ~aherrera/ reportesInternos/ doubleLorentzian.pdf [2] “Practical Methods for Background Subtraction in Photoemission Spectra.” A. HerreraGomez, M. Bravo-Sanchez, O. Ceballos-Sanchez, and M.O. Vazquez-Lepe. Surf. Interface Anal. 2014, 46, 897–905 DOI 10.1002/sia.5453. [3]“The Slope-Background for the Near-Peak Regimen of Photoemission Spectra.” A. Herrera-Gomez, M. Bravo-Sanchez, F.S. Aguirre-Tostado, M.O. Vazquez-Lepe. Journal of Electron Spectroscopy and Related Phenomena 189 (2013) 76-80. (DOI 10.1016/j.elspec.2013.07.006.) [ CHM-347 ] Optical characterization of materials by Spectral Correlation technique and Time Resolve Spectroscopy. Angel Adalberto Duran Ledezma ([email protected]) 1 , Luis Fernando Rojas Ochoa ([email protected]) 1 , Miguel Garcia Rocha 2 1 2 1Depto. de Física, Cinvestav-IPN. Apartado Postal 14-740. México DF 07000. México 1Depto. de Física, Cinvestav-IPN. Apartado Postal 14-740. México DF 07000. México E-mail: aadurn@fis. We present a novel technique to perform the optical characterization of thin films. The technique of spectral correlation in frequency domain is great tool to obtain the main optical properties in real time in thin film such as the diffusion coefficient and the absorption length via of photons scattered in a random turbid medium. We employed the photon diffusion approximation theory and, using the correlation function fitting, applied the technique to the characterization of Teflon slabs of different thickness. We compare these results with measurements performed with Time-resolved Spectroscopy, considering the photon time of flight and we recovered the results for the spectral correlation. *This work has been partially supported by Conacyt/Mexico. 178 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ CHM-368 ] Development of an AC and DC current Hall effect-based measurement system: Application to magnetic metallic glasses A. Rosales-Rivera ([email protected]) 2 , J.J. Melo-Quintero 2 , J.P. López-Tabares 2 , J. Hincapie-Bedoya 2 , H.A. Giraldo-Daza ([email protected]) 2 , H.A. Giraldo-Daza 3 , J.A. Chavarria-Rubio 2 , A.A. Velásquez-salazar 2 , D.F. Gómez-Montoya 2 , A.A. Velásquez-salazar 1 1 Departamento de Ingeniería Eléctrica, Electrónica y Computación, Facultad de Ingeniería y Arquitectura, Universidad Nacional de Colombia, Sede Manizales, Manizales, Colombia 2 Laboratorio de Magnetismo y Materiales Avanzados, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Colombia, Sede Manizales, Manizales, Colombia 3 Universidad de Manizales-Facultad de Ciencias e Ingenieria-GIDIT In the first part, we describe the design and instrumentation of an AC and DC current Hall effect-based measurement system. This system consists of a Current Source (Model 6221 DC-AC, Keithley Instruments Inc.) coupled to a Nanovoltmeter (Model 2182A, Keithley Instruments Inc.) or a Lock-In Amplifier (Model SR 530, Stanford Research System), and an electromagnet (Phylatex) that provides magnetic fields up to 1 T. This system has several measurement facilities including Hall voltage, Hall coefficient, resistance, resistivity, and I-V curves, and can be operated in both DC and AC current modes. The functioning of this measurement system was verified using both a standard sample of copper and several resistor circuits that correspond to simulated metallic and semiconductor samples. In the second part, we use the previous system to study the magneto-transport properties of several materials at room temperature including Iron- and Cobalt-based metallic glasses. We present also an analysis of these magneto-transport properties. 179 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ CHM-415 ] Optical and electrical characterization of surface states effects of AlGaAs/GaAs heterostructures grown by MBE Irving Eduardo Cortes Mestizo ([email protected]) 1 , Leticia Espinosa Vega 1 , Joel Briones 4 , Ravindranath Droopad 3 , Manuel Perez Caro 3 , Cristo Manuel Yee Rendón 2 , Edgar Briones 1 , Víctor Hugo Méndez García ([email protected]) 1 1 2 CIACyT, Universidad Autónoma de San Luis Potosí, San Luis Potosí, 78210 SLP, México Facultad de Ciencias Físico–Matemáticas, Universidad Autónoma de Sinaloa, Culiacán, 80000 CLN, México 3 Ingram School of Engineering, Texas State University, San Marcos, TX 78666, USA 4 Instituto de Estudios Superiores de Occidente, Guadalajara, 45604 GDL, México Surface physics plays an important role in the description of phenomena that are related with the interruption of the infinite translational symmetry of the idealized crystalline solid. The surface of a semiconductor is a particularly simple type of interface, at which the solid is in contact with the surrounding world, nevertheless at nanometric-scale surface-atoms mean an important percent of the whole device altering their optical and electrical properties. Surface and interface physics thus have an enormous impact on research and technology of nanometric devices. In this work, we analyze and measure the effect of surface properties on two-dimensional electron gas (2DEG)-containing AlGaAs/GaAs heterostructures by Photoreflectance (PR) and Raman (RE) spectroscopy in conjunction with Hall measurement (HM). PR exhibits Franz-Keldysh oscillations (FKO) in the region between 1.45 to 1.8 eV which are depending on the built in surface electric field intensity (ES) and depletion-layer width. In heterostructures where the doped layers are located far below the surface, ES is in the range from 5 to 2.5 x107 V/m. Contrariwise, the PR spectra from samples in which the doping layer is close to the surface, did not exhibit FKO, since the built in depletion-region (DR) is very short. Values from 9 to 55 nm of DR were found in our set of samples by RE using the peak amplitude of the longitudinal optical phonons, and the coupled phonon modes [1]. We determinate that FKO appears only for those samples where DR > 20 nm. High intensities of ES generate a strong conduction band-bending which, combined with large DR can avoid the formation of a 2DEG in the case that the 2DEG quantum well falls within the depletion-zone. HM indicates that samples where the intensity of ES is large exhibit low carrier concentration and mobility in the 2DEG. This study allows us to determinate the charge density, electric field at surface and depletion-layer values which can be introduced to a numerical model in order to understand and avoid the surface-states effects on the carrier distribution and conduction band profile of the samples [2]. 180 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [1] X. Chen et al. J. Electrochem. Soc.Vol. 140, issue 7, 2085-2088 (1993). [2] A. Cisneros-de-la-Rosa et al. J. Vac. Sci. Technol. B 32, 02C110 (2014). Acknowledgments: The author acknowledges the financial support of CONACYT, CeMIE-SOL 22, FRCUASLP, INFR-2015-01: 255489 and PNCPN2014-01: 248071. [ CHM-458 ] Symmetry analysis in Bi2Fe2Ga2O9 single crystals F. P. Reyes-Ixta ([email protected]) 1 , M. C. Muñoz-Ramírez 1 , J. Ortiz-Saavedra 1 , H. Tototzintle-Huitle 1 , A. Puga 1 , L. Pérez-Arrieta ([email protected]) 1 1 Unidad Académica de Física. Universidad Autónoma de Zacatecas. Calz. Solidaridad Esq. Paseo La Bufa s/n. C. P. 98060. Zacatecas, Zac. The Aurivillius phases such as Bi2Ga4O9 and Bi2Fe4O9 changes in the symmetry usually occur at a defined temperature known as the Curie temperature (TC). The most common structural change is the tetragonal-orthorhombic and orthorhombic-monoclinic due to the polarization and the ferroelectric character of these materials. Bi2Fe2Ga2O9 compound can be obtained from any of the above compounds by half substituting Fe+3 or Ga+ 3 ions or Ga +3 Fe+3 respectively. These compounds exhibit antiferromagnetic properties with orthorhombic structures and two formulaic units per unit cell (Z = 2). In this work the symmetry of well constructed single crystal of stoichiometry Bi2Fe2Ga2O9 with monoclinic habit is studied. Some works had previously reported a habit and crystalline structure of orthorhombic symmetry (Pbam). In this work, by X-ray diffraction measurements, we conclude that this material have monoclinic symmetry. The chemical etching process allowed us to assign the point group 2/m to this compound. By the Raman microscopy analysis got only 2 different spectra which confirmed that symmetry is monoclinic. In the case of orthorhombic symmetry 4 different spectra are expected. The number of phonons found is lower than calculated for 2 formulaic units (Z), but corresponds very well with those calculated for Z = 1. 181 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ CHM-516 ] Soft magnetic metallic glasses: application in magnetic field sensors, fluxgates. Abilo Andrés Velásquez Salazar ([email protected]) 1,2 , Andrés Rosales Rivera ([email protected]) 2 , Diego Fernando Gómez Montoya 2 , 1 Departamento de Eléctrica, Electrónica y Computación, Facultad de Ingeniería y Arquitectura, Universidad Nacional de Colombia, Sede Manizales, Manizales, Colombia 2 Laboratorio de Magnetismo y Materiales Avanzados, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Colombia, Sede Manizales, Manizales, Colombia Soft magnetic amorphous ribbons of Fe73.5−xCrxSi13.5B9Nb3Cu1 family have a wide variety of sensor applications and because of its high magnetic permeability and high magnetoimpedance can be used in many magnetic sensors, one of them is fluxgate magnetometers. This type magnetometer is used to measure very weak magnetic fields such as those studied in geomagnetism, mineral exploration and space research. Annealing of these ribbons can improve their magnetic properties due to its nanocrystallization. It has been demonstrated that chromium changes the electrical and magnetic properties as it replaces the iron. Furthermore, the universality class of magnetic phase transitions is changing from Ising to Heisenberg, indicating an increase in the itinerant magnetism. A fluxgate sensor system was emulated using a wave generator, a oscilloscope and a two coils, one to generate an alternating magnetic field and the second to pick up the induction produce by a core of a soft magnetic ribbon of Fe73.5−xCrxSi13.5B9Nb3Cu1 family. Ribbons with 0 to 20% chromium content, "as cast" and annealed at 520 ° C were used as cores of the coils. Measures of weak magnetic fields on the order of Earth's magnetic field were performed with each ribbon to determine how the chromium and annealing influence the behavior of the sensor system. Keywords: Soft magnetic metallic glasses, Fluxgate, Sensors, Magnetism. 182 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ CHM-560 ] Characterization of the structure of TiO2 P25 modified by mechanosynthesis Juan Manuel Padilla Flores ([email protected]) 2 , José Ernesto Domínguez Herrera 2 , Octavio Maldonado Saavedra 2 , Erick Adrian Juarez Arellano 1 , Enrique Castillo Zaragoza ([email protected]) 2 1 2 Dpto. Ciencias Quimicas, Universidad del Papaloapan, Av. Universidad S/N Dpto. Nanotecnología, Universidad Tecnológica del Centro de Veracruz, Av. Universidad No. 350 Structural changes in the modified P25 TiO2 were studied from mechanosynthesis method at 650 rpm at different times in air. These materials were characterized by Raman, XRD and UV-VIS reflectance. X-rays show changes in the crystallinity of TiO2 as new corresponding phases appear to deformation generated by the mechanical stress to which it is subjected, also, decreasing grain size generates a frequency-range which reflected in the widening of the diffraction peaks, this behavior is further confirmed in the results of Raman spectroscopy while the spectra of UV-Vis diffuse reflectance, shows that the milling time changes the electrical conductivity of the material, so that the mechanosynthesis applied on the TiO2 can modify the properties of electrical conductivity of the material, also, it was determined that the electrical properties of the material are a function of particle size. 183 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla MICROELECTRONICS AND MEMS (MEM) Chairman: Wilfrido Calleja (INAOE) Horacio Estrada (CENAM) Sesión Poster [ MEM-38 ] Taking advantage of distributed parasitics of aluminum/cooper interconnects for resonant oscillators implementation Ana Karen Armenta Márquez 1 , Mónico Linares Aranda ([email protected]) 1 , Luis Hernández Martínez 1 1 Instituto Nacional de Astrofísica, Óptica y Electrónica. Área de Electrónica, Luis Enrique Erro No. 1, Santa María Tonantzintla, C.P. 72000, Puebla, México. Currently, have emerged several demands (like reliability, speed, signal integrity, power consumption, among others) in the transfer of signals between the different devices that compose the Metal-Oxide-Semiconductor Integrated Circuits (MOS-IC) made on silicon substrate. The generation and distribution of high quality periodic signals where the characteristics of high frequency, low skew and jitter, low power consumption, among others are required in the signal (clock) that serve to synchronize efficiently complex systems, such as microprocessors, and communication systems are every time more tight. In order to partially address these demands, the technologies of MOS-IC have incorporated in their manufacturing process a greater number of interconnection levels made of aluminum and more recently of copper, in conjunction with the use of new insulating materials such as low-k dielectrics that are used to separate the different levels of metal. All this has given rise to the increment of parasitic resistance, capacitance and inductance between the different metal levels due to vias used to connect them and the design of the interconnection lines and their layout, as well as to changes in the manufacturing process. In this work, resonant ring oscillators based on the inductive and capacitive distributed parasitics from on-chip wiring are presented. The configuration used in these oscillators is a single pair of closely spaced rings, implemented on higher metal layer on a MOS-IC. At one end, these rings are connected in a Mobius fashion, and carefully selecting the perimeter of 184 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla the ring, wire width and spacing, the values of the inductive and capacitive distributed parasitics are such that the ring exhibits extremely high frequency oscillations. In these types of resonant oscillators, charge is recirculated, and therefore these oscillators are highly energy-efficient. The parasitic inductance and capacitance of the rings are fixed once the ring perimeter; wire dimensions, layer and spacing are determined. The oscillation frequency of the resonant oscillators is determined by the total parasitic inductance and capacitance values. The resonant oscillators are implemented using a UMC 180 nm Mixed-Mode, Single-Poly 6-Metal (1P6M), P-Substrate, RFCMOS Technology. [ MEM-79 ] Transport N-S-N, F-S-F characterization for the superconductors Nd[Fe, Co]AsO Ariam Mora-Hernández ([email protected]) 1 , Agustín CondeGallardo 1 1 Departamento de Física, CINVESTAV Metal organic chemical vapor deposition technique (MOCVD) and arsenic diffusion processes have been used for synthesis of Nd[Fe, Co]AsO polycrystalline films. The X-ray diffraction and energy dispersive X-ray microanalysis (EDX) indicate that the films have the structure and composition necessary for a superconducting transition at ~15K. The behavior of the electrical resistance confirms this superconducting transition. By using Photolithography technique we create a 2 microns thick line of Nd[Fe, Co]AsO superconductor material and evaporate Au or Fe electrodes on it, to form normalsuperconducting-normal (SNS) or Ferromagnetic-Superconducting-Ferromagnetic (FSF) junctions. With these junctions we measure current-voltage curves both above and below Tc, to see the response of the electron tunneling to normal and magnetic electrodes. Additionally, we try to measure differential conductance to measure the superconducting gap in this material which has not been stablished before. 185 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ MEM-151 ] Electrical characteristics of capacitors made of high-K dielectrics based on Ti(X)Al(1-X)O(Y) thin films Norberto Hernandez-Como ([email protected]) 2 , Francisco Hernandez-Cuevas ([email protected]) 2 , Jacobo Munguia 2 , Salvador Mendoza 1 , Miguel Aleman 2 , Marco Ramirez-Salinas 1 1 2 Centro de Investigación en Computación, Instituto Politécnico Nacional, México. Centro de Nanociencias y Micro y Nanotecnologías, Instituto Politécnico Nacional, México Dielectric materials exhibiting high dielectric constants play critical roles in a wide range of applications including RF MEMS switches, high-sensitivity capacitive pressure sensors and energy-storage capacitors for piezoelectric energy harvesters. In this work, DC reactive sputtering, using metallic targets (Al and Ti) and oxygen/argon plasma, is used to grow oxide films at 100 oC. A dielectric constant (k) over 20 can be achieved in nanolaminate structures by alternatively depositing nanometric layers of aluminum oxide (Al2O3) and titanium oxide (TiO2) films. We have particular interest in the Ti(x)Al(1-x)O(y) (TAO) films because it combines a high-k material (TiO2 with a k>50) and a high band gap material (Al2O3 with a Eg=8.5 eV) which helps to reduce the leakage current. Capacitors, consisting on Glass/ITO/TAO(100 nm)/Au, were fabricated using one lithography step. Current-voltage and capacitance-voltage characteristics were evaluated in order to determine leakage current, capacitance per area and dielectric constant. It was found that the dielectric constant of TAO films can be tuned from 15 to 25 as the sub-layer thickness of the Al2O3 and TiO2 films is decreased from 20 to 5 nm. A minimum leakage current of 10E-7 A was obtained for all the cases. The effect on the leakage current and the dielectric constant dependency over frequency was also studied for different TAO total thicknesses of 100, 200 and 300 nm. The results obtained are encouraging towards application in MEMS technology. 186 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ MEM-220 ] Manufacturing of cantilevers based on hydrogenated amorphous SiGe films Margarita Galindo-Mentle 1 , Rosa Maria Woo-Garcia 4 , Rodolfo Palomino-Merino 3 , Wilfrido Calleja-Arriaga 5 , Carlos Zuñiga-Islas 5 , Agustín Leobardo Herrera-May 2 , Francisco Lopez-Huerta ([email protected]) 4 1 Av. Universidad Tecnológica 1000, Xicotepec de Juárez, Puebla, Mexico Centro de Investigaciones en Micro y Nanotecnología, Universidad Veracruzana, Calzada Ruiz Cortines 455, 94292, Boca del Río, Veracruz, Mexico 3 Facultad de Ciencias Físico Matemáticas, Benemérita Universidad Autónoma de Puebla, Av. San Claudio y Río Verde, Col. San Manuel, 72570, Puebla, Puebla, Mexico 4 Facultad de Ingeniería, Universidad Veracruzana, Calzada Ruiz Cortines 455, 94292, Boca del Río, Veracruz, Mexico 5 Instituto Nacional de Astrofísica, Óptica y Electrónica, Calle Luis Enrique Erro 1, 72840, Tonazintla, Puebla, Mexico 2 We present a manufacturing process of cantilevers using both boron-doped hydrogenated amorphous silicon and hydrogenated amorphous silicon-germanium (aSiB:H and a-Si0.5Ge0.5B:H) films. The cantilevers are fabricated by plasma enhanced chemical vapor deposition (PECVD), at 573 K, 110 kHz and a low pressure (0.8 e-3 atm). The proposed microstructures have seven different length with a single structural layer of 1 µm thickness and are fabricated using surface micromachining. These microstructures showed a good characteristics for their integration in the production of MEMS. Our manufacturing process with hydrogenated amorphous SiGe films is simple and decreases the residual stress of these microstructures. 187 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ MEM-266 ] Manufacturing Piezoresistive Devices Based on Graphite Films Luiz Antonio Rasia ([email protected]) 1, Graciane Hammes 2 , Marina Geremia 2 , Antonio Carlos Valdiero 1 1 Unijuí / DCEEng - Department of Science and Engineering, Rudi Franke Avenue, 540, Panambi, Brazil 2 Unoesc / University of the West of Santa Catarina, Chapecó, Brazil In this paper are shown results of the characterization of piezoresistive sensor elements based on graphite films. The graphite was deposited through direct friction on polymeric substrates. Using mathematical models were extracted the piezoresistive coefficient, πij, these films. The results are compared with amorphous DLC films produced by magnetron sputtering techniques. In these films were obtained longitudinal piezoresistive coefficient in the order of -3.65x10-10 m2/N transverse piezoresistive coefficient -4.5x10-10 m2/N and shear coefficients -1.02x10-9 m2/N. Tests have shown that the change in resistivity is proportional to the load applied to the structure. The proposed arrangement is an alternative way to produce sensor elements using easier techniques of deposition. The arrangement of graphite piezoresistores on polymeric substrates should become a substitutive alternative for conventional force devices, acceleration and pressure made from silicon. 188 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ MEM-449 ] Development of a Virtual Platform for Piezoresistors Project Rodrigo Couto Moreira 2 , Luiz Antonio Rasia ([email protected]) 2 , Marina Geremia 3 , Sandro Sawicki 2 , Humber Furlan 1 1 FATEC/Centro Paula Souza, Coronel Fernando Prestes,Square, 30,Bom Retiro, São Paulo, Brazil 2 Unijuí / DCEEng - Department of Science and Engineering, Lulu Ingelfritz Street, 480, Ijuí, Brazil 3 Unoesc / University of the West of Santa Catarina, Chapecó, Brazil This work shows the development and implementation of a software project for piezoresistive sensing elements. The program is built in Java and uses the classical mathematical models of literature for piezoresistors project. There are many programs that assist piezoresistors projects, but not all are specifically designed for this purpose. Some are used to simulate stages of the processes of diffusion or implantation of impurities, others are used to produce the effect of physical and mechanical structures. In this paper we present a virtual platform that allows you to cross between the electrical properties, thermal and mechanical semiconductor material chosen for piezoresistance project. The results are important parameters for the final design of piezoresistive sensing devices in the laboratory. Otherwise, the platform serves as a teaching tool designs since the simulation results are shown graphically and can be experimentally reproduced. 189 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ MEM-455 ] Hybrid energy harvester prototype based in three different mechanisms: piezoelectric, photovoltaic and Radio Frequency. Adriana Limón Morín 1 , Mario Moreno Moreno 3 , Víctor González Díaz 2 , Fermi Guerrero Castellanos 2 , Richard Torrealba Meléndez 2 , Aurelio Heredia Jiménez 4 , Roberto Ambrosio Lázaro ([email protected]) 2 1 2 Electrical and computing, UACJ, Av. del Charro 450N, Ciudad Juarez, Chih. Electronics department, BUAP, Edif. 109B. Ciudad Universitaria. 18 Sur y Avenida San Claudio. San Manuel. Puebla, Pue 3 Electronics department, INAOE, Luis Enrique E. 1, Sta. Ma. Tonantzintla, Puebla 4 Mechatronics, UPAEP, Calle 21 Sur.1103, Barrio Santiago, 72410, Puebla, Pue Harvesting energy is the process of scavenging power from the ambient energy resources. This ambient energy is related to green energy sources such as solar, thermal, wind, vibrations and electromagnetic radiation. The amount of energy transformed from the ambient sources can power up sensor nodes, low power electronic devices and to recharge a battery, it is a potential solution to realize handheld electronics with long-term operation and also self-powered electronics, therefore to eliminate the need of changing batteries frequently. The devices that harvest energy from the ambient require specific environmental conditions; for instance, solar cells and piezoelectric generators require sunlight and mechanical vibration, respectively. Since these conditions do not exist all the time, most energy harvesters do not generate a constant stream of electricity. In order to increase the output power to bias the electronic systems and to harvest energy continuously is necessary to combine different types of harvesting mechanisms. In this work is presented the prototype of a hybrid energy harvesting circuit which integrates piezoelectric, photovoltaic and electromagnetic energy harvesting mechanisms. It contains a piezoelectric cantilever based on Lead-Zirconate Titanate piezoelectric transducer (PZT) in order to harvest the ambient vibrations, a solar cell for sunlight and an antenna capable to harvest ambient Radio Frequency (RF) energy. The design and implementation of the circuits: AC to DC for the case of piezoelectric generator, and the antenna and its signal conditioning circuits for RF to DC are presented. The RF harvesting circuit operates in the 2.45 GHz range with obtained voltage of 17mV. The prototype is capable to generate a maximum DC power around 241.3 mW when the piezoelectric, solar cell and RF devices are connected together. Thus, the output power of this hybrid harvesting circuit is very attractive for low power electronic applications. 190 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ MEM-477 ] Characterizing printed antennas at microwave frequencies using two popular coaxial interfaces: a fair comparison Maria de la Luz Garcia Cruz ([email protected]) 2 , Reydezel Torres Torres ([email protected]) 1 , Marco Antonio Ramírez Barrientos 2 1 Coord. Electrónica, INAOE. Luis Enrique Erro No. 1, Tonantzintla, Puebla, México C.P. 72840. 2 Fac. Electrónica, UPAEP. 21 sur 1103 Barrio Santiago, Puebla México, C.P. 72410. Nowadays, printed circuit board (PCB) technology is widely used to implement highspeed electronic platforms for communication purposes. Therefore, it is highly desirable to integrate antennas over PCB substrates to reduce cost and optimize area. For this reason, much research has been carried out to provide designers with methodologies for implementing reliable antennas on PCB. In fact, printed antennas with different structures are implemented these days using metal traces separated from the ground plane by composed dielectrics. These are the well-known microstrip-based antennas, and the pattern for these devices is selected by considering the frequency range of operation, input impedance, and radiation pattern, among other important features. Once the antenna is designed and prototyped, a rigorous verification of its appropriate operation is required to warranty that the requirements specified for a particular application are met. In this regard, one of the most important tests performed to an antenna fabricated on PCB is that carried out to ensure that the frequency of resonance (i.e., the frequency at which the device is required to operate) as well as the input impedance fall at values within the tolerances defined at the beginning of the design process. For this purpose, the standard tool employed to carry out this test is a vector network analyzer (VNA), which applies high frequency signals to the antenna and measures the power that is reflected back at particular frequencies within a band specified by the user. Therefore, for practical reasons, in order to apply and sense signals to a PCB antenna using a VNA, an interface is required. This is due to the fact that the VNA presents a coaxial connector input/output terminal, whereas the antenna is terminated with the form of a microstrip line. Thus, bear in mind that not only the mechanical match of the microstrip with the VNA is necessary, but it is also necessary to optimize the interface to avoid that the electromagnetic fields applied by the measurement equipment leaks away from the device under test (DUT) due to undesirable signal reflections. In a microwave laboratory there are two main forms to practically characterize printed antennas on PCB: directly using coaxial microwave connectors attached to the board, and using a universal test fixture (UTF). Both methods present advantages and disadvantages 191 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla involving several technical aspects; hence, whereas directly using coaxial connectors is a considerably more popular practice due to the easy and direct implementation, using a carefully calibrated UTF allows to greatly reduce the effect of the parasitic introduced by the measurement setup by using a calibration technique that defines the measurement plane at the level of the DUT. Therefore, the research reported here involves a systematic evaluation of the error introduced by employing both techniques, allowing the microwave designer to select the more appropriated approach to characterize a prototype. It is shown that at early design stages, it would be acceptable to use coaxial connectors since approximate values for the characteristic impedance defining the input features of the antenna are obtained; similar results are obtained for the frequency of resonance. Notwithstanding, the acceptable results obtained in this case, using a UTF is highly recommended for validating the operation of an antenna on PCB before incorporating the device within the full system. Carefully performed experiments support these conclusions. [ MEM-481 ] Microfluidic device fabrication on glass substrates with deep channels César Bartolo Pérez ([email protected]) 1 , Claudia Reyes Betanzo 1 1 Electronics Department, National Institute of Astrophysics, Optics and Electronics, Luis Enrique Erro # 1, Santa María Tonatzintla, 72840, Puebla, México In order to fabricate microfluidic devices with deep channels, two masking layers used for wet etching were characterized. The aim is to reduce their residual stress to avoid defects like cracks or peeling off that could reduce the quality of the glass surface and the performance of the device. First, a bilayer Cr/Cu was deposited by evaporation. Through the variation of the Cu layer thickness, the stress is reduced. The second masking layer is amorphous silicon deposited by PECVD. Different deposition conditions were applied, varying the temperature (140-200°C), pressure (600-900 mTorr) and power (15-30 W), followed by a thermal annealing at different times. The stress calculations were made using the Stoney equation and roughness of the films characterized by AFM measurements. With a bilayer of Cr (50 nm)/Cu (250 nm) has been obtained microfluidic devices with channels of 83 m deep, while for the amorphous silicon layer, the depth obtained is 186 m. 192 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ MEM-509 ] Silicon as a MEMS material Rodolfo Briseño Rodríguez ([email protected]) 1 , Perla Itzel Alcántara Llanas 1 , Ana Paulina González Arceo 1 , Manuel Bandala Sánchez 1 1 Microelectronic Systems Department, CIDESI, Av. Playa Pie de la Cuesta 702, Querétaro, México The last decades have seen an ever-increasing use of silicon for the fabrication of miniaturized systems, this development has been driven by the road maps in the microelectronics industry, but during the last few years the focus of the field is shifting toward the use of silicon for fabrication of microelectromechanical systems (MEMS) due to its versatility, its mechanical properties, the wealth of potential silicon-based novel applications and its cost as is one of the most abundant elements on earth, compatible with most batch-processed integrated circuits technologies. This work presents an overview of the reasons why silicon has such an special place in fabrication of MEMS, its advantages, limitations, and its expected routes of new development. [ MEM-526 ] A new method for the micromachining of silicon by a laser-ablation and chemical etching hybridprocess Horacio Estrada ([email protected]) 1 1 Centro Nacional de Metrología, Querétaro, QRO A novel method for the micromachining of silicon wafers will be reported. The purpose in mind is to find a way to speed up the chemical etching process as well as to achieve the chemically etching of (111)-silicon wafers to be able to form membranes or other structures on these substrates. The method includes the ablation with a laser of silicon wafers, followed by traditional etching processes using KOH or TMAH. The ablation process damages the exposed surface resulting on a rather random array of 3D grains. The depth of the damage depends on the power set on the laser. The damaged region can be readily etched out, to yield a relatively smooth surface after few minutes in the etching solution at temperatures below the traditional 90oC, widely used for those alkiline solutions. The attractive results of this hybrid method are the ability to obtain circular membranes on (100)-wafers, which are usually obtained using plasma etching methods; whereas on (111)-wafers, relatively circular 193 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla and rectangular deep (200µm) membranes can be achieved within a few hours of etching at 50oC after the corresponding ablation process. Details and results from this work will be presented, and different perspectives for the use of this hybrid method will be highlighted for the fabrication of nozzles, or to reduce the plasma etching times and costs, often necessary when SOI-wafers are included in a device's protocol. [ MEM-534 ] Design and Fabrication of Touch Mode Capacitive Pressure Sensor for Biomedical applications using a Surface Micromachinig Fabrication Module Daniela Díaz Alonso ([email protected]) 3 , Mario Moreno 3 , Luis Niño de Rivera 2 , Félix Gil 1 , Juan Manuel Álvarez 3 , Ignacio Juárez 3 , Víctor Aca 3 , Armando Hernández 3 , Adrián Itzmoyotl 3 , Wilfrido calleja 3 1 APEC, Hospital Luis Sánchez Bulnes, D.F. México 2 IPN ESIME-Culhuacan, D.F. México 3 LI-MEMS INAOE, Puebla, México This paper presents a new design and fabrication scheme of Touch-Mode Capacitive Pressure Sensor (TMCPS), which can be used in a wireless integrated RLC implant circuit for monitoring pressure in biomedical applications. The work is focused on the design, simulation and fabrication of dynamic capacitors, based on surface micromachining with Poly-Si and Aluminum films as top electrode, both structural materials were covered with a 1.5µm-thick Polyimide film. The capacitive microstructures have been developed using the PolyMEMS-INAOE technology® for surface micromachining. The novelty of the method includes two important aspects: First, the capacitors are designed as a planar cavity within a rigid frame, where two walls contain channels, which allow etching of the sacrificial material and simplifies the complementary sealing process to a fully monolithic fabrication scheme. Second, the electromechanical structures are designed using a composite model, such model includes a Polyimide film capping for precise pressure sensing, giving protection for the internal cavity, and at the same time, providing full biocompatibility. Results show the diaphragms are fully flexible and mechanically stable, the composite model fits perfectly the mechanical behavior, and the PolyMEMS-INAOE technology® is perfectly suited to develop pressure sensor devices with manufacture stages at high (Poly-Si) and low temperatures (Aluminum). In addition, we are presenting a proposal to integrate a telemetric system with this pressure device for a future implantable stage. 194 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ MEM-542 ] Implementation of a Second-Order LowPass Active Time-Varying Filter with a SymbolicModelled Memristor Arturo Sarmiento-Reyes ([email protected]) 1 , Luis HernándezMartinez 1 , Jesús Jiménez León 1 , Gerardo Ulises Díaz Arango 1 , Hector Vázquez-Leal 2 1 INAOE, Electronics Department, Luis Enrique Erro 1, 72840 San Andrés Cholula, Puebla, Mexico 2 Universidad Veracruzana, Faculty of Eectronic Instrumentation Analog filtering plays an important role in the design of front ends in various systems that span from signal processing systems, control systems, telecommunications systems to instrumentation systems. In modern electronics, the requirements for analog filtering systems are no longer exclusively related to implement a given transfer function in the frequency domain that fulfills certain specifications related to the gain in a pass band and attenuation in the reject band, in fact more features have been incorporated to these systems. Adaptability and programmability are some characteristics that are commonly expected in the implementation of analog filters in order to make the designs compatible with high performance electronics. A smart form of incorporating these characteristics to analog filter design is by generating structures whose parameters change with the time, i.e. time-varying filters. This can be done by linking a time-dependent function to the constitutive branch relationships of those elements in the filter structure that define the most important parameters of the transfer function such as gain, quality factor and cut-off frequency.On the other side, the specific memory-resistance property of the memristor makes this device specially suited for implementing time-varying filters. In this paper, the time-varying feature of the filter is achieved by using a memristor as the element that controls the the parameters of the transfer function. In this form, the time-dependance of the memristor is reflected in the overall transfer function of the structure. The result is a filter that possesses identical frequency-domain response as the original filter plus a faster settling time. In addition, the memristor is modelled with a fully analytic i-v function that becomes an excellent feature for including the device in the electric simulation procedure.Waveforms, transient-response and the complete design flow of the filter are presented in the final manuscript. 195 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla NANOSIENCE AND NANOSTRUCTURES (NSN) Chairmans: Máximo López Lopez (CINVESTAV) Jaime Santoyo Salazar (CINVESTAV ) Cristo Manuel Yee Rendon (UAS) Oral Session INVITED TALK [ NSN-76 ] Nano-structured ZrO2 co-doped with rare earth ions with multicolor and white emission Alma Isabel Ramos Guerra 1 , José Guzmán Mendoza 1 , Manuel García Hipólito 3 , Ciro Falcony Guajardo 2 1 Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, IPN, Miguel Hidalgo 11500 D.F., México 2 Centro de Investigación y Estudios Avanzados, IPN, Gustavo A. Madero 07360 D.F., México 3 Instituto de Investigación en Materiales, UNAM, A.P. 70-360 Coyoacán 04510 D.F. For this research, the hydrothermal synthesis as well as the characterization in morphology, structure, chemical composition and photoluminescent properties of intrinsic ZrO2 as well as co-doped with rare earths ions (RE) is reported. The intrinsic and co-doped ZrO2 was synthesized using chlorides (ZrOCl2.8H2O, EuCl3.6H2O, TbCl3.6H2O and TmCl3.6H2O all with a purity of 99.99% from Aldrich brand) as precursor materials; deionized water as solvent and NaOH to take the solution pH to 12. The reaction was carried out for 1.5hrs at 200°C; parameters that were kept fix during the whole synthesis; however, concentration of each dopant was varying in order to determine the optimal concentration of each RE, results that were used to establish the combination of RE to obtain luminescent emissions of different colors. The EDS results confirmed the presence of the rare earth ion in the doped samples and a stoichiometric relationship close to the ideal. The X-ray diffraction results showed that the co-doped and the intrinsic ZrO2 powders presented a combination of crystalline structures, monoclinic and tetragonal, since the dopant concentration was not enough to stabilize only the tetragonal phase. Furthermore, using this results and Scherrer's formula, the size of the 196 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla crystal was estimated around 11nm; results that were confirmed through HRTEM. As for the results concerning luminescent properties, the samples were excited using a wavelength suitable for the three RE ions. The spectra showed a combination of characteristic emission lines of each RE present in the sample Tb3+ (5D4 7F5), Tm3+ (1G4 3H6), and Eu3+ (5D0 7 F1 4); apparently with a transfer of energy or an overlap of emission liens. The mixture of emission lines allowed to have samples with emissions of different colors including white, since the color of the emission can be controlled with the amount of solution of each dopant in the synthesis solution [ NSN-93 ] Structure and luminescence of CdTe embedded porous silicon Claudia de Melo ([email protected]) 5 , Guillermo Santana 2 , Jaime Santoyo 4 , Gabriel Romero 1 , Johnny Ferraz 3 , Moni Behar 3 , Osvaldo de Melo 5 1 Electrical Engeenering Department, Centro de Investigación y Estudios Avanzados del Instituto Politécnico Nacional, CINVESTAV-IPN, A.P. 14-740, México D.F. 07360, México 2 Instituto de Investigación en Materiales, Universidad Nacional Autónoma de México, Cd. Universitaria, A.P. 70-360, Coyoacán 04510, México D. F. 3 Ion Implantation Laboratory, Institute of Physics, Federal University of Rio Grande do Sul, CP 15051, CEP 91501-970, Porto Alegre, RS, Brazil. 4 Physics Department, Centro de Investigación y Estudios Avanzados del Instituto Politécnico Nacional, CINVESTAV-IPN, A.P. 14-740, México D.F. 07360, México 5 Physics Faculty, University of Havana, Colina Universitaria, 10400 La Habana, Cuba Porous silicon (PS) is a promising matrix host for embedding different materials, such as semiconductors [1,2], metals or conductive oxides [3,4] with a wide range of applications. This is because the properties of both the PS and the embedded material can be modified in the final composite. Such composites offer new and interesting properties depending on the kind of embedded material and its morphology. Several techniques have traditionally been used to infiltrate PS films. They include sol- gel [5], multiple step process including impregnation and thermal or chemical treatments [6], atomic layer deposition [7], and electro-deposition [8] among others. In this work, the results of using isothermal closed space vaporization technique (ICSV) for embedded CdTe in porous silicon (PS) are presented. The structure of the embedded material is determined by X-ray diffraction analysis, which allows identifying the formation of two different crystalline phases of CdTe. Micrographs of the samples taken with transmission and 197 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla scanning electron microscopes allow determining the size of the PS pores, and the size and shape of CdTe grains grown on the inner surface of PS. Direct measurements of compositional profiles through Rutherford backscattering spectrometry (RBS) are presented; these measurements allow demonstrating the feasibility of this technique to incorporate the CdTe inside the pores of mesoscopic PS. We show that filling of PS with CdTe causes changes in the PS refractive index and in their luminescent properties. While the virgin PS shows the typical red emission, the embedded one displays an intense wide emission at room temperature along the whole visible range. Measurements of photoluminescence vs. temperature from 11 K up to 288 K allow identifying two different emission bands: a red and a blue band. The behavior of the energy gap and integrate intensity vs. temperature suggest the red emission arise not from the CdTe, but from the PS itself; the role of CdTe is to promote this emission trough passivation of the PS surface. We believe that this emission is associated to direct recombination of photo generated carriers into Si nanocrystals. On the other hand the energy of the blue band practically does not change with temperature, due to that we suppose that it arise from transition of deep levels inside the SiO2 gap. [1] C. de Melo, S. Larramendi, V. Torres-Costa, J. Santoyo-Salazar, M. Behar, J. FerrazDias, O. de Melo, Micropor. Mesopor. Mater., 188, 93 (2014). [2] O. de Melo, C. de Melo, G. Santana, J. Santoyo, O. Zelaya-Angel, J. G. MendozaÁlvarez, and V. Torres-Costa, Appl. Phys. Lett., 100, 263110 (2012). [3] R. G. Singh, F. Singh, V. Agarwal, R. M. Mehra, J. Phys. D: Appl. Phys., 40, 3090 (2007). [4] P. Granitzer, K. Rumpf, Materials, 3, 943 (2010). [5] Szilági, Z. Hajnal, F. Pászti, O. B uiu, G. Craciun, C. Cobianu, C. Saaniu, É. Vázsonyi, Mater. Sci. Forum, 248, 373 (1997). [6] A. I. Belogorokhov, L. I. Belogorokhova, A. Pérez-Rodríguez, J. R. Morante, S. Gavrilov, Appl. Phys. Lett., 73, 2766 (1998). [7] C. Docsö, N. Quoc Khanh, Z. Horváth, and I. Bársony, M. Ufrialnen, S. Lebto, M. Nieminen, L. Niinistö, J Electrochem. Soc., 143, 683 (1996). [8] Farid A. Harraz, Tetsuo Sakka, Yukio H. Ogata, Electrochim. Acta, 50, 5340 (2005) 198 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-94 ] Basic Modification of Multi-walled Carbon Nanotubes (MWCNT) by Heating Reflux for Possible Application as Catalysts in Biodiesel Production Christian Cabello Alvarado ([email protected]) 3 , Pascual Bartolo Pérez 1 , Susana Rincón Arriaga 2 , Alejandro Zepeda Pedreguera 3 , Julio Sacramento Rivero 3 1 CINVESTAV-Unidad Mérida, Carretera antigua a Progreso Km 6, A.P. 73 Cordomex, C. P. 97310, Mérida, Yucatán, México. 2 Instituto Tecnológico de Mérida, Av. Tecnológico Km. 4.5 S/N, C.P. 97118, Departamento de Ingeniería Química-Bioquímica, Mérida, Yucatán, México. 3 Universidad Autónoma de Yucatán, Facultad de Ingeniería Química, departamento de química inorgánica, Campus de Ingenierías y Ciencias Exactas, Periférico Norte Km. 33.5, Tablaje Catastral 13615, Col. Chuburná de Hidalgo Inn, C.P. 97203, Mérida, Between the alternatives to replace fossil fuels it has been proposed the use of new products that do not damage the environment and generate lower cost. Biodiesel is an excellent energy to offset the high cost of petroleum diesel. This biofuel consists of alkyl esters from vegetable oils or animal fats that react chemically with short chain alcohols in the presence of a catalyst to carrying out the transesterification reaction. The catalysts can be classified in homogeneous and heterogeneous as zeolites, sulfonic resins, some oxides and carbon-based catalysts. The multi-walled carbon nanotubes (MWCNT) have properties as high mechanical strength, exceptional electrical properties and thermal resistance, also the elevated relation of diameter-length and high surface area make them suitable for application in the field of catalysis. Additionally of these characteristics, through chemical oxidation of the MWCNT can be added various functional groups as carboxylic acids, amines and amides, which helps their interaction with other molecules. This research focuses on study the production of MWCNT modified whit amines by heating reflux, to establish processes for obtaining nanoparticles that can be used as catalysts in the production of biodiesel. The nanocatalysts characterization was performed by XPS spectroscopy and SEM-EDX analysis and stability tests to confirm dispersed suspensions of the modified nanoparticles. The results of XPS spectroscopy using modified MWCNT showed the presence of a peak in 399.9 eV corresponding to N1s, while the unmodified MWCNT not signal appears. The other peaks were identified to C1s (284.43 eV) with high intensity and related O1s (532.16 eV) low intensity. In the SEM-EDX analysis the presence of nitrogen it was observed in the EDX spectra for the modified MWCNT. In the semicuantitative analysis the values obtained were of 90.01 wt % for C, 3.29 wt % for O and 6.7 wt % for N, in the pristine MWCNT the nitrogen was not detected. Dispersions of the modified MWCNT were stable for 24 hours in polar solvents. 199 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-97 ] Controlled Synthesis and Formation Mechanism of Silver Nanowire Didier Castañeda García 3 , Alejandro Rodríguez Juárez ([email protected]) 4 , Josefina Aguila Lopez 3 , Joel Díaz Reyes 1 , Jesús Antonio Fuentes García 4 , Jaime Santoyo Salazar 2 , José Luis Jiménez Pérez 4 , José Francisco Sánchez Ramírez ([email protected]) 1 1 CIBA-Instituto Politécnico Nacional. San Juan Molino Km 1.5 de la Carretera Estatal Sta. Inés Tecuexcomac-Tepetitla, Tlaxcala, 90700. México. [email protected] 2 Centro de Investigación y de Estudios Avanzados de Instituto Politécnico Nacional, Departamento de Física, Av. IPN 2508, San Pedro Zacatenco, C.P. 07360, A.P. 14-740, 07000 México, D.F., Mexico 3 Instituto Tecnológico Superior de Tlaxco, Predio Cristo Rey Ex Hacienda de Xalostoc s/n Carretera Apizaco Tlaxco Km. 16.8 C.P.90250 Tlaxco Tlaxcala, México 4 UPIITA-Instituto Politécnico Nacional, Av. Instituto Politécnico Nacional 2580. Barrio Laguna Ticoman 07340. México D. F. The synthesis of silver nanowires (Ag NWs) with high quality is challenging because of the low selectivity of the formation of multiply twinned particles at the nucleation stage for subsequent Ag NWs growth. We report a systematic study of the controlled synthesis of Ag NWs with high rate in a simple and scalable preparation method. Using glycerol as a reducing agent and a solvent with a high boiling point, the reaction is rapidly heated to 150 °C in air to synthesize Ag NWs with a very high yield in gram level. The obtained Ag NWs are highly crystalline, monodisperse and exhibit adsorption in the range of 350−400 nm. By simply varying the temperature of reaction, the formation of Ag NWs can be controlled. Visual color changes between 40 - 140 °C were observed in the colloidal dispersions. The formation of Ag NWs has been confirmed using the techniques UV-Vis spectroscopy, XRD and TEM. A possible growth mechanism of the Ag NWs is given. The authors are thankful to the Mexican Agencies, CONACYT, SIP-IPN and COFAA-IPN for financial Supports. 200 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-108 ] Cubic GaN grown on GaAs substrates by RF-plasma-assisted Molecular Beam Epitaxy Y.L. Casallas-Moreno ([email protected]) 5 , D. A. FloresCordero 1 , S. Gallardo-Hernández 5 , B. M. Monroy 4 , A. HernándezHernández 3 , G. Santana 4 , A. Escobosa-Echavarría 2 , M. López-López 5 1 Chemical Department, Escuela Superior de Ingeniería Química e Industrias Extractivas Electric Engineering Department, Centro de Investigación y de Estudios Avanzados del IPN 3 Escuela Superior de Apan, Universidad Autónoma del Estado de Hidalgo 4 Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México 5 Physics Department, Centro de Investigación y de Estudios Avanzados del IPN 2 GaN epitaxial films with high cubic phase purity were grown on GaAs(100) substrates by RF-plasma-assisted Molecular Beam Epitaxy (RF-MBE). The films were synthesized at different growth temperatures ranging from 710 to 730°C. An As overpressure was employed during the nucleating layer. We found the optimum conditions for the nucleation of the cubic GaN using the As overpressure. Higher cubic phase of GaN was obtained for samples that initiated the relaxation process after some monolayers (8ML) of growth, as a result of better stabilization of the cubic layer. The relaxation process depends on the As overpressure over the growth surface and on the growth temperature. The structural details of GaN by highangle annular dark-field STEM (HAADF-STEM) and high resolution X-ray diffraction (HRXRD) evidenced the purity of cubic phase in the first nanometer of growth, and also the formation of planar defects as stacking faults. We identified the stacking faults along the [111] planes, as result of the strain relief caused by the large lattice mismatch between GaN and GaAs, and the incorporation of hexagonal phase over these facets. The identification and quantification of h-GaN was performed by X-ray reciprocal space mapping (RSM). We obtained the highest cubic phase purity of 98.7% for cubic GaN grown at 720°C. The photoluminescence spectra of the samples clearly show emission peaks of c-GaN. This work was supported by Sener-Conacyt No. 151076. 201 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla INVITED TALK [ NSN-117 ] Nano and micro structures in alkali halide films produced by pulsed laser deposition Dwight Acosta ([email protected]) 2 , Elsi Mejia 1 , Citlali Sanchez 1 1 Centro de Ciencias Aplicadas y Desarrollo Tecnológico de la UNAM 2 Instituto de Física de la UNAM The alkali halide (AH) family are materials with cubic symmetry and it is constituted by positive sodium or sodium ions and negative chloride ions. These compounds are insulators with wide band gap and by its simple crystalline composition are often used as model structure to validate and try new theories and experiments. Thus, recently these materials have been researched as promising host for self-assembly of luminescent nanostructures. The AH are synthesized with different growth processes in bulk and thin film configuration, according to faces the electric properties change, thus for the NaCl the (100) surface is electrically neutral and (111) surface is electrically charged. Arranging and control of atomic structures and molecular on insulating thin film are of great interest in device miniaturization. In the insulating materials, and in particular in NaCl, the epitaxial growth of thin films and its self-assembly process is highly important for nanotechnological applications due to its high-quality in the growth of layer by layer . Monocrystalline NaCl and KCl materials, from International Crystal Laboratories, were used respectively as targets during Pulsed LaserDeposition process, which in turn, was carried out in an UHV chamber at pressure 10 mTorr using excimer laser at 248 nm, with an output energy 50 mJ at 10 Hz. The PLD system used operation was controlled with a computer. The substrates were located in front o the target and several distances target-substrate were tried : 45, 55, 60, 70, 80 mm. The substrate temperature was increased from room temperature up to 300, 400 and 500 ºC respectively and the number pulses was rised sequentially from 4800 to 24000 shots. The characterization of thin films was carried out with a SEM JEOL LV 5600 and a STEM JEOL 2010 electron microscopes, a Bruker D8-Discovery X-rays diffractometer, an AFM AutoProbe CP (Park Scientific Instruments). Nano and micro thin films were produced by PLD on glass and on polymer substrates From SEM and STEM micrographs analysis the simultaneous ocurrence of three growing process can be stablished:1)The atomic and molecular clusters formation, 2) the micro and nano grains coalescence process 3) the self ensamble of the nanocrystal cluster as a function of substrate temperature, deposition chamber pressure and laser pulses number. Electron micrographs suggest that nucleation and coalescence rates are different for nano and micro AH crystallites, during film synthesis and the big crystallites do not growth at the expenses of small ones while the flow of alkali halide material from target is impinging continuously on substrate The results suggest that beside the clasics films growth models (Volmer-Weber, Frank- van der Merwe and Stranski-Krastanov) other possibilities must be considered to explain the Alkali Halides films formation and growth under PLD deposition. 202 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-325 ] Influence of zinc acetate on the glass coating for the growth of zinc oxide nanowires by hydrothermal method Marco Alberto Ayala-Torres ([email protected]) 1 , Concepción Mejía-García 1 , Josué Romero-Ibarra 2 , Gerardo Ortega-Cervantes 1 1 2 ESFM - IPN IIM - UNAM In this work, the study of the glass substrate coatings where the ZnO nanowires grow was carried out. The glass coating was performed by centrifugation, zinc acetate solutions of 1, 10 and 100 mM in 1-propanol, with three cycles of spin coating at 2000rpm for 100s were deposited. At the end of each cycle the substrate was introduced in a muffle furnace for 1 min at 100°C. ZnO nanowires were obtained immersing the substrates in an equimolar solution of zinc nitrate hexahydrate and hexamethylenetetramine (HMTA) to 25 mM in deionized water. A commercial microwave oven at different power settings of 300, 500 and 700W for 20 min for the thermal treatment was used. The ZnO nanowires obtained were characterized structural, optical and morphologically using XRD, UV-VIS transmission and Scanning Electron Microscopy (SEM), respectively. XRD patterns spectra revealed the presence of Zn(OH)2 on the films. The ZnO nanowires bandgap energy for the films grown on glass was obtained optical transmission spectra (3.24 eV). The influence of the zinc acetate concentration in the coating density and the morphology of the nanowires was studied. 203 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-337 ] Growth and characterization of MoSe2 single crystals and MoSe2-MoS2 heterostructures Andres de Luna Bugallo ([email protected]) 1 , Daniel Rubin 3 , Fangze Liu 3 , Estelle Cohen 2 , Swastik Kar 3 1 CINVESTAV-Queretaro 2 Harvard University 3 Northeastern University Over the last decade, a considerable amount of bi-dimensional materials have been obtained either by exfoliation or deposition techniques including the possibility to form heterostructures [1,2]. Among all these new nano-materials, transition metal dichalcogenides (TMDs) particularly Molybdenum and Tungsten based TMDs are intrinsic semiconductors with well defined bandgap values between 1-2 eV, making them promising candidates for many optoelectronic and nanoelectronic applications[3]. In this work we present the synthesis and characterization of single layer MoSe2 crystals as well as a novel method obtain MoSe2-MoS2 vertical and lateral heterostructures. First, MoSe2 nanosheets were grown using chemical vapor deposition (CVD) on SiO2. Micro-Raman spectroscopy shows dependent thickness on the vibrational modes, monolayers present a photoluminescence enhancement related to the indirect to direct bandgap crossover. MoSe2 FET devices were fabricated by means of e-beam lithography, backed gated measurements revealed high gate mobility around 20cm2V-1s-1. The devices also show a photoresponse of 2 orders of magnitude under UV illumination. Lateral and axial MoSe2-MoS2 monolayer heterostructures were epitaxially grown using a simple and controllable technique based on a CVD two-step process. Micro-Raman and PL spectroscopy and imaging show spatially contributions of different vibrational modes and luminescence of the two materials over the structures. In particular photoluminescence spectra show that the emission can be tuned from 1.55 to 1.85 eV. Finally crystallinity of the MoSe2-MoS2 heterostructures was studied by transmission electron microscopy (TEM). [1] Sheneve B. et. al. ACS Nano, 2013, 7 (4), pp 2898–2926 [2] Yongji G. et. al. Nature Materials 13, 1135–1142(2014) [3 ]Fengnian Xia, Han Wang, Di Xiao, Madan Dubey & Ashwin Ramasubramaniam, Nature Photonics 8, 899–907(2014) 204 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-382 ] Study of the formation of Au nanoparticles produced by pulsed laser annealing Citlali Sánchez-Aké ([email protected]) 1 , Jimena Martínez de León 1 , Tupak García-Fernández 2 , Mayo Villagrán-Muniz 1 1 Laboratorio de Fotofísica, Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México, Apartado Postal 70-186, México D.F., C.P. 04510, México 2 Universidad Autónoma de la Ciudad de México (UACM), Prolongación San Isidro 151, San Lorenzo Tezonco, México D.F., C.P. 09790, México Metallic nanoparticles (NPs) either covered or embedded in dielectric matrices like glasses have received great attention for their linear and non-linear optical properties and its possible applications as plasmonic structures. One suitable technique for the synthesis of metallic NPs is pulsed laser annealing. In this method, laser irradiation of thin metal films on non-wetting substrates produces heat instabilities and melting that lead to the disaggregation of the film into nanoislands and nanoparticles. Moreover, it has been shown that for laser fluences above a certain threshold, the NPs can be implanted into glass substrates [1]. This technique can be perfomed at room temperature and atmospheric conditions and is free of chemical wastes and lithography requirements [2]. The aim of this work is to investigate the formation of gold NPs using in situ characterization techniques. The NPs were produced by laser annealing of Au films on both glass and fused silica substrates. We employed a Nd:YAG laser emitting pulses of 7 ns of duration and 355 nm. With the aim to better understand the mechanisms involved during the annealing, realtime optical absorption, laser beam deflection and pulsed photoacoustic measurements were used to monitor the formation of the NPs. The obtained NPs were characterized later by SEM and UV-Vis optical absorption. The influence of the laser fluence, number of pulses, repetition rate, film thickness and the background pressure on the characteristics of the NPs was studied. [1] S.J. Henley, M.J. Beliatis, V. Stolojan, S.R.P. Silva, "Laser implantation of plasmonic nanostructures into glass", Nanoscale 5, 1054 (2013). [2] M.J. Beliatis, N.A. Martin, E.J. Leming, S.R.P. Silva, S.J. Henley, "Laser ablation direct writing of metal nanoparticles for hydrogen and humidity sensors", Langmuir 27(3), 1241 (2011). 205 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-393 ] Mechanisms for the Self-Assembly of GaAs Nanofacets in High-Index GaAs Substrates prepared by MBE Reyna Méndez Camacho ([email protected]) 1 , Victor Hugo Méndez García 1 , Esteban Cruz Hernández 1 1 Coordinación para la Innovación y la Aplicación de la Ciencia y Tecnología, CIACYTUASLP, Sierra Leona 550, S. L. P., S. L. P., México. Controlled formation of periodically ordered one-dimensional (1D) nanostructures is interesting for fundamental science and applications [1]. Among the variety of methods available for the 1D semiconductor quantum wires (QWRs) fabrication, self-assembly on high index (H-I) substrates by molecular beam epitaxy (MBE) is very promising because does not require additional processing that may introduce defects to the nanostructures. Natural formation of periodic corrugation in H-I substrates it is due to the energetic unstable surfaces that tend to break up into low free-energy surfaces, which then can be used as templates for growing QWRs arrays with high uniformity and density. However, in spite of the substantial experimental investigation on self-assembling of uniform corrugation on H-I GaAs substrates [2], there is a lack of theoretical studies concerning to the surface atomic mechanisms behind the origin of nanoscale corrugation. In this work, we report the study of the self-induced surface corrugation in the MBE homoepitaxial growth of GaAs on GaAs(631) through Density Functional Theory (DFT) by using a Perdew-Zunger (LDA) exchange-correlation pseudopotential. We found that the assembling of the ~ 60 nm-width terraces of the surface corrugation is triggered by the formation of smaller ~ 4 nm-long nanofacets. A generalization of this mechanism for other H-I orientations is also discussed. [1] V. A. Shchukin and D. Bimberg, “Spontaneous ordering of nanostructures”, Rev. Mod. Phys., Vol. 71, 4, (1999). [2] E. Cruz-Hernandez, et al., Appl. Phys. Lett. 101, 073112 (2012). Acknowledgments: The author acknowledges the financial support of CONACYT, CeMIESOL 22, FRC-UASLP, INFR-2015-01: 255489, PNCPN2014-01: 248071, and CB: 168761. 206 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-411 ] Analytical study of In shallow implanted GaN Carlos Hernández Gutierrez ([email protected]) 3 , Yuriy Kudriavtsev 2 , Maximo López López 1 , Victor Sánchez Resendiz 2 , Arturo Escobosa Echavarria 2 , Jaime Santoyo Salazar 1 , Angel Guillen 1 1 Departamento Física, Cinvestav Departamento Ingeniería Eléctrica - SEES, Cinvestav 3 Doctorado en Nanociencias y Nanotecnología, Cinvestav 2 Ion implantation is a widely used method to form a p- or n-type semiconductor layers. In last years the ion implantation became a very popular technique to form metal and semiconductor nano-particles inside of oxides [1-4]. We performed a low energy (25keV) and a high doses (from 2.5 to 5 x1015 ions/cm2) implantation of Indium in GaN epi-layers, grown by MOCVD on a sapphire substrate. Both p-type (Mg doped) and n-type (Si- doped) GaN epi-layers were used. The energy and the doses were selected to reach the In concentration of around 5-7 atomic % at the implanted maximum. After implantation the samples were heated in ammonia atmosphere under 400oC during 30 minutes. Two possible results have been suggested originally: a formation of InN (or In) nano-particles in a near surface GaN layer, or a formation of top InxGa1-xN ternary layer. To confirm or reject the suggestions we performed a complex analytical study of the implanted and annealed samples by using SIMS, RAMAN, TEM, XRD and PL methods. Raman confirmed formation after implantation of In-N bonds and demonstrated indium oxide peaks, as well. The last peaks disappeared after a thermal annealing in ammonia atmosphere. SIMS showed a quite similar In distribution before and after annealing. XRD with a glancing angle confirmed a formation of InxGa1-xN ternary with different composition (x). PL spectrum shown several peaks, which were indentified corresponding to electron transitions in InxGa1-xN ternary. But after all, TEM images demonstrated a formation of nanoparticles (InN?) with the typical dimension of around 10nm. In this report we discuss obtained results and speculate about possible applications of In high doses implantation in III-nitrides structures. Reference [1] A.E. White et al. Appl.Phys.Lett. 50 (1987) 95 [2] M.Strobel, S.Reiss, K.H.Heinig, Nucl. Instr. Meth. B120 (1996) 216 [3] B.Schmidt, K.H.Heinig, A.Mücklich, Mat. Res. Soc. Proc. 647 (2001) 011.20.1 [4] A. W. Wood, X. Weng. Applied Physics Letters 99, 093108 (2011) 207 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-431 ] Nanoparticles produced by laser ablation in liquid enviroment Luis Alberto Hernández-Hernández ([email protected]) 5 , Arturo Hernández-Hernández ([email protected]) 4 , Jaime SantoyoSalazar 2 , Francisco de Moure-Flores 6 , José Guadalupe Quiñones-Galván 1 , Miguel Meléndez-Lira 3 1 Centro Universitario de Ciencias Exactas e Ingenierías, Blvd. Marcelino García Barragán #1421, esq Calzada Olímpica, C.P. 44430, Guadalajara, Jalisco 2 Departamento de Física, Centro de Investigación y de Estudios Avanzados - I.P.N., C.P.07360 México, D.F 3 Departamento de Física, Centro de Investigación y de Estudios Avanzados - I.P.N., C.P.07360 México, D.F. 4 Escuela Superior de Apan, Universidad Autónoma del Estado de Hidalgo, Calle Ejido de 5 Escuela Superior de Física y Matemáticas – Instituto Politécnico Nacional, Edificio No. 9, U.P.A.L.M., San Pedro Zacatenco, C.P. 07738 México D.F. 6 Facultad de Química, Universidad Autónoma de Querétaro, Querétaro C.P. 09790 México The formation of ZnS, ZnO, Ge, Si and SiGe alloy nanoparticles under laser ablation of solid targets in liquids environment is reported. The use of an Nd:YAG laser allow high rate of nanoparticles formation as a sol. The nanoparticles are characterized by X-ray diffraction (XRD), UV-Visible transmission spectroscopy and transmission electron microscopy (TEM). The nanoparticles size dependence on both the laser fluence and the nature of the liquid is studied. In some cases, nanoparticles of compounds are formed via reaction of the target whit the liquid. 208 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-490 ] Structural and compositional analysis in Zinc Oxide-Graphene Oxide. Edith Bravo Gonzalez 2 , Aaron Israel Diaz Cano 2 , Efrain Rubio Rosas 1 , Yosemik Arjuna Leon Nataret ([email protected]) 2 1 Benemerita Universidad Autónoma de Puebla, CUVYTT, San Manuel, 72570, México 2 Instituto Politécnico Nacional, UPIITA, Gustavo A. Madero, 07340, México The optical and structural properties were discussed for the Zinc Oxide-Graphene Oxide (ZnO-GO) nanomaterial. It used a physical method to grow the material using the Microwave Assisted Hydrothermal method. The preparation were using 0.07 mmol of Zn(CH3COO)2∙2H2O and 0.5 M NaOH in 50 ml aqueous solution, stirred for 30 min. The GO was synthetized by the modified Hummers method and applied sonication for 10 min. In the prepared solution it added 0.3 ml GO, 5 ml DFM (Dimethylformamide) and 15 ml H 2O deionized to teflon container. The digestion oven parameter were for the first step 5 min – 800W – 130°C – 15 min and the second 15 min – 700W – 110°C. Finally the samples were cooled 20 min for his subsequent extraction, washed with Ethanol, centrifuged at 3500 rpm and dried at 55°C for 5 hrs. XRD obtained information about the crystalline structure and shown a hexagonal phase to correspond to wurtzite structure (JCPDS 36-1451) in relation to ZnO and a little peak in 22.5° (2theta degree) that could be to relate with GO due to approximation with FCC graphite phase (002) and the chemistry exfoliation process. An unusual morphology was observed by SEM analysis, the material has an appearance like tulip with nanometric sizes (150-500 nm) and homogeneous surface, this structure resembles a fractal configuration. EDS microanalysis obtained weight values of 24.89%W, 23.68%W and 51.43%W for C, O and Zn respectively like atomic relation. FTIR obtain information about the chemical bonding in the material. It has bands attributed to vibrational modes like H-O-H assigned to a small amount of H2O in the ZnO nanocrystals around 1592 cm-1, bands in 828 cm-1 and 678 cm-1 are assigned to the vibrational frequencies due to charge in the microstructural features into Zn-O lattice. The Zn-O bond is assigned to stretching frequency at 542 cm-1 for pure ZnO and the O-H vibrational frequencies at 3326cm-1. For GO functional groups the bands attributed to vibrational mode are C-O, O=C=O, C-H, O-H, -COOH centered in 1242cm-1, 2320 cm-1, 2933 cm-1 and 3354 cm-1 respectively. PL spectroscopy shows different emission bands associated to defects and the modification of ZnO crystal structure due to incorporated of GO in the lattice´s material, the pure ZnO in the lattice and the ability of ZnO particles to transfer photogenerated electrons to GO has been demonstrated from quenching of ZnO emission. 209 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-522 ] Strain Distribution of InAs Nanostructures Grown on GaAs by MBE. Eric Eugenio López ([email protected]) 1 , Irving Eduardo Cortes Mestizo 1 , Víctor Hugo Méndez García ([email protected]) 1 1 Center for the Innovation and Application of Science and Technology (CIACyT), Autonomous University of San Luis Potosí (UASLP), Av. Sierra Leona #550, Lomas 2a Sección, SLP 78210, México. The Quantum dots (QDs), being the only structures that present atom-like properties, are the most promising candidates for developing the next-generation technologies. Although several major challenges have still to be overcome for the improvement of the QDs quality and distribution, these nanostructures are often considered as the basis for numerous nanoelectronic devices and applications. The QDs are commonly grown on dissimilar materials (different lattice constant and parameters) to propitiate the accumulation of strain in the interface, which is the main mechanism of the formation self-assembled QDs, the StranskyKrastanov growth mode. In such cases once the nucleation of the QDs is achieved, due to the lattice mismatch, the strain in the structure is reduced but also a thin InAs wetting layer (WL) remains below the QDs. The remaining strain within the QDs is known to impact their electronic structure and therefore their opto-electronic properties. On the other hand, photoreflectance (PR) spectroscopy is a technique focused on the band bending modulation (i.e. surface electric field modulation) [1]. This spectroscopy, as expected, is sensitive to the electric field produced by the remaining strain in the heterostructure, therefore able to study it. In this work the strain distribution involved in the whole structure InAs/GaAs was studied: inside the InAs 3D nanostructures, along the 2D wetting layer, and in the bulk GaAs substrate. The effect of strain on the energy bands split is analyzed by two-dimensional simulation of hydrostatic strain in the QDs structure. The simulation indicates that the energy band diagram is modified by the WL thickness and the QDs topology, which determine the strain in the GaAs topmost monolayers. Our numerical results are supported by experimental analysis performed by PR. [1] J. Misiewicz, Opt. Elec. Rev. 20(2), 101 (2012). The author acknowledges the financial support of CONACYT, CeMIE-SOL 22, FRCUASLP, INFR-2015-01: 255489 and PNCPN2014-01: 248071. 210 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla Sesión Poster [ NSN-39 ] Influence of silicon dioxide nanoparticle on the mechanical properties of concrete mixtures Fernando Marcial ([email protected]) 2 , Leandro García 1 , Julián Hernández 1 , Arturo Ayon 3 1 CENTRO DE INVESTIGACION EN MICRO y NANOTECNOLOGIA, UNIVERSIDAD VERACRUZANA, Calzada Ruiz Cortines # 455, Fracc. Costa Verde, C.P. 94294, Boca del Río, Veracruz. MEXICO 2 FACULTAD DE ING. MECANICA ELECTRICA, UNIVERSIDAD VERACRUZANA, Lomas del estadio S/N, Col. Zona Universitaria, C.P. 91000. Xalapa, Ver, MEXICO. 3 MEMS Research Laboratory Dept. of Physics and Astronomy. The University of Texas at San Antonio, USA Abstract. We describe the influence of silica nanoparticles in the compressive strength of a concrete, hereby referred to as nanoconcrete. The exercise comprised the preparation of two types of mixtures, namely, (i.) Portland Composite Cement (CPC 30R), sand and coarse aggregate (gravel) with water cement (W/C) ratio of 0.59 and (ii.) the aforementioned components plus silica particles (sand grains with 95% of SiO2) to produce nanoconcrete. The exercise included several nanoconcrete samples that were prepared by varying the content of the silica particles in the proportions of 15%, 20% and 30% by weight of CPC 30R cement used while preserving the W/C ratio = 0.59. These prepared mixtures were tested in their fresh and hard state under uniaxial compression. In order to correlate the observed performance with the microstructure of these blends, the mixtures were characterized employing X-Ray Diffraction (XRD) to determine the size of the particles of silica (56 nm) and cement CPC30R (130 nm), Scanning Electron Microscopy (SEM) to observe the microstructure of the produced concrete samples, and Energy Dispersive X-Ray Spectroscopy (EDS) to obtain the specific mineralogical components of concrete and nanoconcrete. The measure response indicated that strength increased by 15% when silica nanoparticles where added to the mixture paving the way for the prospective proliferation of this technique. Keywords. Nanoparticles of silica sand, concrete nanostructured, concrete pattern, nanoconcreto, CPC30R Portland Cement. 211 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-43 ] Study of two and three interacting particles in Graphene type lattices within the Gereralized Hubbard Model Edmundo Emmanuel del Muro Arteaga ([email protected]) 1 , Sergio Molina Valdovinos 1 , Jaime Raúl Suárez López 1 1 Universidad Autónoma de Zacatecas, Unidad Académica de Física, Calzada Solidaridad esq. Paseo, La Bufa s/n, C.P. 98060, Zacatecas, Zac. México. Graphene, a two-dimensional material formed by a single layer of carbon atoms ordered in a honeycomb lattice. Electron-electron interactions in graphene are expected to play an important role due to its low dimensionality, and many-body effects have received great attention [1,2]. In this work, we study the electronic correlation for two and three interacting particles with parallel and antiparallel spins in a graphene lattice using a real space method previously reported [3], and the generalized Hubbard model, which includes interactions between electrons at the same site and at nearest neighbours sites, and also an occupation dependent hopping. The method consists in mapping the many body problem in an equivalent one described by an tight binding Hamiltonian with site and bonding impurities. Using translational symmetries of impurities, we can project the states space in a lower dimensional one. Then, we analyse electronic correlation by the calculation of the bonding energy, that is, the energy difference between the bonding state and the non-bonding state of lowest energy, for different values of the hopping parameter and potential interactions. We obtain the behaviour of the wave function and its physical implications in the graphene lattice when electronic correlations are present. Keywords: electronic correlation, graphene, electrical and electronic properties [1] Phys. Rev. B 77, 073412 (2008). [2] Phys. Rev. Lett. 111, 036601 (2013). [3] Phys. Rev. B 77, 115410 (2008) 212 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-45 ] Optical near field diffraction by a conducting double slit under Leontovich impedance boundary approximation Juan Sumaya Martinez ([email protected]) 2 , Gustavo Montiel Gonzalez ([email protected]) 1 1 2 Physics Dept., Universidad Autonoma del Estado de Mexico Physics Dept., Universidad Autonoma del Estado de Mexico. Instituto Literario 100, Col.Centro. Toluca, Edo. Mex. The optical near field diffracted by a metallic double slit ruled in a thick conducting metallic screen is numerically studied. The Leontovich impedance boundary condition is used at the metallic interfaces for gold, silver and aluminum. Using incident plane waves the optical near field is computed above, within and below the double slit system for the two fundamental cases of polarization S and P. The diffracted field is analyzed as a function of the slit width (particularly at the subwavelength regime), the reffractive index of the metal and the thickness of the metallic screen. Finally a comparison with the case of a perfect conducting screen is performed. 213 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-50 ] Effect of stirring speed in the structural properties of pbse nanoparticles obtained by colloidal synthesis Edgar Cabrera Guerrero ([email protected]) 1 , Enrique Rosendo Andres 1 , Roman Romano Trujillo 1 , Gabriela Nieto Caballero 2 , Tomas Diaz Becerril 1 , Hector Juarez Santiesteban 1 , Mauricio Pacio Castillo 1 , Godofredo Garcia Salgado 1 1 CIDS-ICUAP FCQ-BUAP 2 Nanoparticles of lead selenide (PbSe NPs) have been obtained through colloidal synthesis in aqueous solution. The synthesis was carried out at room temperature and the stirring speed was varied 60 to 1200 r.p.m. HRTEM measurements shown that the distance between planes are 0.24 nm y 0.36 nm associated with (220) and (111) crystalline planes of PbSe respectively. SEM measurements shown that all samples the presence of agglomerates of PbSe is observed, however the presence of bars which may be selenium is also appreciated, but also as the value of revolutions increases, these bars disappear. The crystal sizes are 1013 nm, 11-14 nm and 12-15 nm for molar concentrations of (1:1), (1:2) and (1: 3) respectively as was calculated XRD measurements, also was found that the PbSe NPs have the face-centered cubic phase. Micro-probe Raman spectroscopy was used to prove the existence of optical phonon mode LO(Г) of PbSe nanoparticles prepared by colloidal chemistry. EDS analysis shown the 1:1 Pb/Se stoichiometry is favored when the stirring speed is 1100 r.p.m. 214 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-60 ] Radial Breathing Modes and optical properties in Ti Nanoparticles obtained by green synthesis Ricardo Andrés Britto Hurtado ([email protected]) 1 , Ramón Alexis Alvarez Bayona 1 , Manuel Cortez Valadez 1 , Mario Flores Acosta 1 , Humberto Arizpe Chavez 1 1 Universidad de Sonora In this research, we present the results of experimental and theoretical study of nanoparticles of titanium (Ti) as the main reducing agent using the plant extract of Nopal (Opuntia ficusindica) to synthesize metal nanoparticles. Optical absorption, Raman spectroscopy, EDS, TEM was used for characterization. Absorption bands located at 395 and 355 nm was detected after reduction of the titanium ions. Nanoparticles with an amorphous structure were visualized with a size less than 10 nm in diameter, on the other hand, nano crystal structures were formed with sizes of 1-4 nm. The presence of Ti in the particles was confirmed by EDS. It was found that the Raman spectrum shows bands at low wave numbers of 359 and 404 centered cm-1. Vibrational properties of Tin clusters (n = 2-13) using the theory of density functional DFT were used, finding radial breathing modes in each cluster between 387-298 cm-1. The calculations used in the level of B3LYP approach in combination with the LANL2DZ basis set. [ NSN-69 ] AFM study of epitaxial layers grown from InAs liquid phases on the isoperiodical GaAs and InGaP substrates Edith Guadalupe Castillo Baldivia ([email protected]) 1 , Andrei Yu. Gorbatchev 1 , Viatcheslav A. Mishurnyi, 1 , Francisco Javier De Anda Salazar 1 , Ulises Zavala Moran ([email protected]) 1 1 UASLP-IICO In a previous work [1] it has been shown that Liquid Phase Epitaxy (LPE) can be used to grow quantum dots if there is a lattice mismatch between the epitaxial layer and substrate and if the growth conditions lie far outside the thermodynamic equilibrium because of the generation of elastic energy due to stress in the epitaxial layers[2]. But the thermodynamic equilibrium in the liquid-solid interface is determined as well by the difference in chemical compositions between the solid and liquid phases. 215 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla The objective of this work is to study the morphology of lattice matched LPE layers grown simultaneously, from a single InAs liquid phase, on substrates with different compositions: GaAs and InGaP/GaAs. The growth experiments were done at a liquidus temperature of 450°C with a supercooling of 6°C. Contact times were 1, 5 and 15 seconds. Samples were characterized by Atomic Force Microscopy (AFM). Every epitaxial layers surface contains nanoislands whose of heights and diameters are in the range of 2-65 nm depending on the growth time and on the substrate kind. For the same experiment, the nanoislands average sizes are larger when grown on InGaP and have higher densities and rougher surfaces as compared to the nanoislands grown on GaAs. But the nanoislands grown on GaAs substrates have more uniform distributions of heights and diameters. Furthermore, it is convenient to mention ripples that appear on the surface of the epitaxial layer grown on InGaP with 5 seconds the ripples are parallel to [0-11]. These studies allow us to conclude that in the case of growth of low dimensional structures by LPE their properties are determined by the magnitude of the thermodynamic disequilibrium that includes not only the effect of the elastic energy generated by the mismatch between the epitaxial layer and the substrate but also by the difference in the chemical compositions in the interface liquid-solid. [1]Journal of Physics: Conference Series 167(2009) 012002 [2]Journal of Crystal Growth 57 (1982) 84-90 [ NSN-70 ] FeSe2 nanoparticles using hydrothermal method: Structural, morphological and optical characterization M.V. Morales Gallardo ([email protected]) 1 , N.R Mathews ([email protected]) 1 , A.M Ayala 1 , M. Pal 2 1 Instituto de Energías Renovables, Universidad Nacional Autónoma de México, Temixco, Morelos 62580, México 2 Instituto de Física, BUAP, Av. San Claudio y Blvd. 18 Sur Col. San Manuel, Ciudad Universitaria, C.P. 72570, Puebla, México Iron pyrite is a nontoxic and earth abundant material which has wide applications in the fields such as, thin film solar cells, photoelectrochemical cells, and photocatalysis. An optical band gap of about 1 eV and the high absorption coefficient of 105 cm-1 make this material suitable for the above mentioned applications. The work was focused on the development of phase pure FeS2 nanoparticles by hydrothermal synthesis. The chemicals used were FeSO4 as a precursor of Fe and Na2S2O3 as a source of sulfur (S) using water as the only solvent. The crystallization process of the material was studied by annealing at different temperatures in 216 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla N2 atmosphere. Finally, it was concluded that thermal treatment at a temperature of 280 °C for 3 h in N2 was the most appropriate condition to obtain pure pyrite. The product was characterized by X-ray diffraction (XRD); the structural studies showed the formation of phase pure FeS2 which was further confirmed by Raman spectrum. Morphological characterization by scanning electron microscopy (SEM) showed the formation of compact rod like structure. The estimated band gap energy was of 1.7 eV which is higher than the bulk FeS2 (0.9 eV). The work for the development of thin films using these nanoparticles is under progress and the structural and optical properties of the films will be discussed. Acknowledgements: Authors acknowledge María Luisa Ramón García for the XRD analysis and José Campos for technical support in material characterization This work was supported by the project: CONACYT Ciencia Basica 238869, IN107815, CeMIE-Sol P28 [ NSN-78 ] Effect of rapid thermal annealing ambient of SRO films obtained by hfcvd Angel Mena ([email protected]) 1 , Godofredo Garcia ([email protected]) 1 , Tomas Diaz 1 1 CIDS-BUAP Photoluminescent and vibrational properties of SiOx films deposited on crystalline silicon sustrates (100) and annealed in a rapid thermal annealing (RTA) process are reported in this work. The films were deposited by the Hot Filament Chemical Vapor Deposition (HFCVD) technique, using molecular hydrogen (H2) and a fused quartz rod (SiO2) as a solid source. The filament-source distance was keeped constant at 2mm in all process. Source-substrate distance was adjusted at 1, 2, 3, 4 and 5mm. The characteristic peaks of the before annealing SiOx films; stretching, bending and rocking, observed by FTIR spectroscopy showing a dependence of the position with the growth temperature. The photoluminiscence peaks show the best intensity around 750nm. After annealing in RTA hydrogen atmosphere at 900oC the FTIR peaks remain almost the same, but the photoluminscence spectra shows a width increase for about twice that the original sample the first in 750nm and second in 690nm The deconvolution of the photoluminiscence spectra shows two principal peaks, one of them remain in the same wavelenght in all cases 750nm, and the other presents a shift to short wavelengths 660nm. This phenomena is attributed to creation of nanocrystals and radiative defects in the SiOx films, the formation process of nanocrystals during the RTA appear to be depending of the film density. 217 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-89 ] Synthesis, characterization and simulation of copper oxide nanoparticles. J.I. Valencia-Lima ([email protected]) 3 , E. Rubio-Rosas 1 , M.A. Morales-Sanchez 2 , R. Agustín-Serrano 1 1 Centro Universitario de Vinculación y Transferencia de Tecnología, Benemérita Universidad Autónoma de Puebla. Av. San Claudio y 18 sur C.U. Col. San Manuel, C. P. 72570. Puebla, Pué. México. 2 Facultad de Ingeniería Química, Benemérita Universidad Autónoma de Puebla. Av. San Claudio y 18 sur C.U. Col. San Manuel, C. P. 72570. Puebla, Pué. México 3 Facultad de Ingeniería Química, Benemérita Universidad Autónoma de Puebla. Av. San Claudio y 18 sur C.U. Col. San Manuel, C. P. 72570. Puebla, Pué. México. Copper oxide nanoparticles, using copper acetate and sodium hydroxide as precursors, polyvinylpyrrolidone as surfactant and ascorbic acid as reducing agent in aqueous solutions, were synthesized. A drawback in the synthesis of such nanoparticles is due to it operates at a nanoscale, their morphology and size are difficult to handle; since a small increase / decrease in temperature or concentration can generate big changes. Therefore, a mathematical model from the reaction kinetics taking place in the synthesis is proposed. The model control parameters can create an appreciation of parameters to be varied to obtain morphology and specific particle size. The nanoparticles were characterized by X-ray diffraction and scanning electron microscopy, showing a cubic crystal habit and particle size within 100 nm. Testing their antibacterial activity by incorporating them into hydroxyapatite as a biomaterial in bone filling is of particular concern. The impregnated hydroxyapatite showed antimicrobial properties, offering an excellent inhibition zone. [1] D. Yu, V.W. Yam, J. Am. Chem. Soc. 126 (2004) 13200. [2] Y. Zhao, J.J. Zhu, J.M. Hong, N. Bian, H.Y. Chen, Eur. J. Inorg. Chem. 20 (2004) 4072. [3] A.Kaminaga,V.K Vanag and I.R. Epstein, J.Phys. Chem. 122,174706(2005) [4] I.R Epstein, I. Lengyel, S. Kadar, M. Kagan and M. Yokoyama(1992) "New Systems for Pattern formation studies." Phys. A 188,26-33 218 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-95 ] Application of Silver Nanowire to Cotton Fabric for Develop a Superhydrophobic Textile Josefina Aguila Lopez ([email protected]) 3 , Alejandro Rodríguez Juárez 4 , José Fernando Huerta Rosas 2 , José Ángel Juárez Torres 2 , Jesús Antonio Fuentes García 4 , José Luis Herrera Pérez 4 , José Francisco Sánchez Ramírez ([email protected]) 1 1 CIBA-Instituto Politécnico Nacional. San Juan Molino Km 1.5 de la Carretera Estatal Sta. Inés Tecuexcomac-Tepetitla, Tlaxcala, 90700. México. [email protected] 2 Facultad de Ingeniería, Ingeniería Textil, Benemérita Universidad Autónoma de Puebla, Puebla, 72570, México. 3 Instituto Tecnológico Superior de Tlaxco, Predio Cristo Rey Ex Hacienda de Xalostoc s/n Carretera Apizaco Tlaxco Km. 16.8 C.P.90250 Tlaxco Tlaxcala, México 4 UPIITA-Instituto Politécnico Nacional, Av. Instituto Politécnico Nacional 2580. Barrio Laguna Ticoman 07340. México D. F. We present a facile and effective method to prepared superhydrophobic cotton textile. Silver nanowire were synthesized by a polyol process and then were conformal coated onto individual cotton fibers through a simple dip and dry process. SEM images revealed a thin and uniform silver nanowires coating on the cotton microfibers which was supported by a surface chemical analysis by EDS. Further modification of the nanowire-containing cotton textile with octyltriethoxysilane led to hydrophobic surface. Surfaces prepared showed a sticky property, which exhibits a static water contact angle of ˃ 150° for a 10 µl droplet that water drop did not slid off even when the sample was held upside down. These modified cotton textiles are potentially useful in a wide variety of applications. The authors are thankful to the Mexican Agencies, CONACYT, SIP-IPN and COFAA-IPN for financial Supports. 219 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-114 ] Preparation and characterization of porous anodic aluminum oxide films for solar thermal applications Samuel Santiago Cruz ([email protected]) 1 , Julio Rodríguez González 2 , Eduardo Mercado Aguilar 2 , Arturo Fernández Madrigal 1 1 Instituto de Energias Renovables Universidad Nacional Autonoma de México, Privada Xochicalco S/N Temixco, Mor, México C.P. 62580 2 Universiad Tecnológica de Huejotzingo Camino Real a San Mateo S/N Santa Ana Xalmimilulco Huejotzingo, Pue, México C.P. 74169 Porous anodic aluminum oxide films on substrates aluminum 1050 (99.5% Al) were produced by anodizing with Direct Current Voltage (DCV), in phosphoric acid 2 M, the potential was varied from 15 to 30 DCV. Time and temperature were kept constantly at 20 minutes and 18oC respectively. The anodized potential effects in transversal and surface parameters of the films was studied by scanning electron microscopy (SEM), SEM micrographs revealed film thickness between 670 and 1200 nm, 35-65 nm pore diameters and barrier layer thickness of 25 and 35 nm on average. According to the current vs. time graph, it was possible to observe four states in pore formation and porous film formation. After the anodizing process, an increase in the oxygen content was observed due to the formation of aluminum oxide on the surface of the substrate. Before the anodizing process, the maximum diffraction peak corresponded to the plane (220), however, after the process the maximum diffraction peak was seen as (111). The Porous anodic aluminum oxide films could be used as selective absorber coatings in solar thermal applications with the parameters observed, when nickel nanoparticles are electrodeposited at the bottom of the pores by use an alternating current (AC). 220 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-122 ] Comparison of two morphologies base on TiO2 according to its photocatalytic activity José Alberto Isidoro Olvera Rodríguez ([email protected]) 1 , Carlos Guzman Martinez 1 , Eduardo Arturo Elizalde Peña 1 , Karen Esquivel Escalante ([email protected]) 1 1 UAQ Nowadays the wastewaters are an important issue, especially the water polluted with drugs. When the wastewater is treated, the traditional methods are not enough, because they may cause that the pharmaceutical pollutants react with the chemicals added for the decontamination process, and the obtained products could be even more lethal to the human being. The solution for this problem is the use of advanced oxidation processes, especially the photocatalysis with TiO2. The purpose of this investigation is to change the morphology of the TiO2, to determine if the morphology of the material has a significant role in the treatment of wastewaters. The nanoparticle of TiO2 was obtained through sol-gel synthesis, and to obtain the nanotube structure, this was carried out by alkaline hydrothermal reduction assisted by microwave process. The characterization of the material was made by TEM, S-BET, Raman Spectroscopy and diffuse reflectance. Results According to the TEM micrograph was possible to achieve the change of the morphology, obtaining from crystalline TiO2 nanoparticles, TiO2 nanotubes, Those can be observed however is not homogeneous the formation and distribution of this structure. The synthesis method must be improved in order to obtain the desired structure and distribution. 221 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-124 ] Self-organized TiO2 nanotubes functionalized with iron oxide nanoparticles: Effect of annealing and the concentration of iron in the precursor solutions Geraldine Hernandez ([email protected]) 2 , Wilson Lopera 2 , Maria Elena Gomez 2 , Walter Torres 1 1 Department of Chemistry, Universidad del Valle, Cali, Colombia 2 Department of physics, Universidad del Valle, Cali, Colombia When activated by UV light, TiO2, a common semiconducting material, is used as a photocatalyst for the degradation of organic compounds and the water splitting reaction. Nanostructuring TiO2, in the form of nanotubes, for instance, significantly improves surface area, which in turn enhances the oxide catalytic activity. For the last 30 years, strategies to activate TiO2 with visible light have been implemented that aim at decreasing the energy band gap between the valence and conduction band of TiO2 and preventing the recombination of photo-generated electrons and holes in the material. While narrowing of the band gap has been achieved by doping TiO2 with selected cations and anions, the issue of prevention of electron-hole recombination has been addressed by the synthesis of hybrid materials between TiO2 and other oxides, for instance, Fe2O3, in which the photo-generated electrons and holes can be spatially separated. Although heterojunctions between TiO2 nanotubes and Fe2O3 have been produced by chemical and electrochemical means, a typical problem is that the interface between the two oxides is not well defined. In this work, we report a novel electrochemical approach for the preparation of hematite, a-Fe2O3 rods inside TiO2 nanotube films electrochemically deposited on Ti electrodes. The structural and morphological properties of the FeTiO2 nanohybrids are characterized by X-Ray diffraction and high-resolution-scanningelectron and atomic-force microscopies as a function of the electrosynthesis variables and annealing temperatures. Acknowledge: This research was sponsored by research project No 1106569331046, C.I 7917 COLCIENCIAS-UNIVALLE; Center of Excellence on Novel Materials "CENM". 222 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-144 ] Synthesis and characterization of zinc cobaltite nanostructures in low concentrations of dodecylamine Juan Pablo Morán Lázaro ([email protected]) 1 , Florentino López Urías 4 , Oscar Blanco Alonso 3 , Verónica María Rodríguez Betancourtt 5 , Israel Ceja Andrade 3 , Alejandra Carréon Alvarez 2 , Rocío Castañeda Valderrama 2 , Marciano Sánchez Tizapa 2 , Amaury Suárez Gómez 2 1 Departamento de Ciencias Computacionales e Ingeniería, CUValles, Universidad de Guadalajara, Carretera Guadalajara-Ameca Km. 45.5, Ameca, Jalisco 46600, México. 2 Departamento de Ciencias Naturales y Exactas, CUValles, Universidad de Guadalajara, Carretera Guadalajara-Ameca Km. 45.5, Ameca, Jalisco 46600, México. 3 Departamento de Física, CUCEI, Universidad de Guadalajara, Jalisco 44410, México. 4 Departamento de Materiales Avanzados, IPICYT, Camino a la Presa San José 2055, Col. Lomas 4a sección, San Luis Potosí, S.L.P. 78216, México. 5 Departamento de Química, CUCEI, Universidad de Guadalajara, Jalisco 44410, México. Zinc cobaltite (ZnCo2O4) is a p-type semiconductor material with spinel-type structure which has been mainly used as electrode for Li-ion batteries and supercapacitors due to its higher electrochemical performances and higher conductivities. In this work, ZnCo2O4 nanostructures have been prepared by a simple microwave-assisted colloidal method, using zinc nitrate, cobalt nitrate and dodecylamine, dissolved in ethyl alcohol. The solvent evaporation was made by applying microwave radiation at low power (~ 147 W). Various concentrations of dodecylamine were used to control the surface morphology of ZnCo 2O4 powders. Micro-rods (length of 20-40 µm), porosity (pore of ~ 2 µm) and semispherical particles (diameter of ~ 0.42 µm) were observed by SEM, when 1, 2, and 3 g of dodecylamine were used, respectively. While, nanoparticles were confirmed by TEM. X-ray powder diffraction measurements indicated the formation of spinel compound ZnCo2O4 at a calcination temperature of 800 °C. Five vibrational modes were acquired by Raman spectroscopy and the main absorption bands were registered by UV-Vis spectroscopy. These last measurements confirmed the formation of the ZnCo2O4 phase. 223 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-148 ] Polymethylmethacrylate (PMMA) fibers reinforced with carbon nanotubes obtained by the electrospinning technique Rosa Yetzira Ponce Cano ([email protected]) 1 , Jorge R. Aguilar Hernández 1 , María de los Ángeles Hernández Pérez 2 1 Escuela Superior de Física y Matemáticas - I.P.N., Edificio No. 9 U.P.A.L.M., Lindavista C.P. 07738 México D. F. 2 Escuela Superior de Ingeniería Química e Industrias Extractivas - I.P.N., Edificio No. 8 U.P.A.L.M., Lindavista C.P. 07738 México D. F. In this paper we present results concerning the manufacture of polymethylmethacrylate (PMMA) fibers reinforced with carbon nanotubes, obtained by electrospinning from polymers in solution. Electrospinning involves a potential difference of the order of 15 kV or more, applied between a metal needle, which contains a polymer solution, and the collector consisting of a copper plate. Continuos increase of the potential difference between the electrodes will overcome the surface tension thereby expelling a fiber which is deposited on the collector surface. In this work we obtained PMMA fibers 15% weight by appliying a potential difference of 15 kV for a distance of 7 cm between electrodes. Moreover, another pair of parameters, such as the type of solvent and the concentration of the solution, were also varied. For the characterization of the fibers scanning electron microscopy, Raman spectroscopy and FTIR spectroscopy were used. The results of this work showes that carbon nanotubes were added in an ordered way, mostly perpendicular to the cross section of the PMMA fibers. 224 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-155 ] CHARACTERIZING THE DOSIMETRIC PROPERTIES OF ZnO UNDOPED AND DOPED WITH Tb Alejandro Ortiz Morales 1 , Epifanio Cruz Zaragoza 2 , Manuel García Hipolito 3 , Ramón Gomez Aguilar 1 1 Instituto Politécnico Nacional, UPIITA, Av. IPN, No. 2580 Col. La Laguna Ticomán, Gustavo A. Madero. México, D.F., C.P. 07340 2 Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, A.P. 70-543, 04510 México D.F., México 3 Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México,, 04510, México D. F., México It is well known that zinc oxide (ZnO) presents dosimetric properties when it is exposed to ionizing radiation. This work reports some dosimetric properties of a new batch of Tb-doped ZnO samples. This material was prepared by a spray pyrolysis (SPM) method. The morphologic characterization of the samples was analyzed by Scanning Electron Microscopy (SEM). The dosimetric properties such as: linearity on the function of the gamma doses, f(D) and g(D) indexes and superlinearity, and the effect of heating rate (2°C/s – 40°C/s ) on the ZnO were investigated. The linear response was between 0.5 kGy and 4 kGy. Also the loosing of thermoluminescent response or fading up to 120 days was analyzed. The glow curves during the fading decay were analyzed by the Glow Curve Deconvolution method (CGCD) based on the mixed order kinetic to obtain the kinetics parameters. 225 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-158 ] Core-Shell Magnetite-ZnO synthesis assited by sonochemistry Ramon Rodriguez Lopez ([email protected]) 2 , Karen Esquivel Escalante ([email protected]) 2 , Carlos Guzman Martinez 2 , Luis Antonio Ortiz Frade 1 , Eduardo Arturo Elizalde Peña 2 1 CIDETEQ 2 UAQ The photocatalytic technology is an easy and cheap method for the treatment of organic and inorganic non-biodegradable pollutants in the wastewater. The synthesis of a photocatalytic material magnetically separable for its reutilization, can be done through a core-shell structure, using a magnetite core (Fe3O4) for its magnetic properties and photocatalytic zinc oxide (ZnO) as shell. Sonochemistry is used for the synthesis of the core-shell structure, using magnetite synthetized by coprecipitation method, and ZnO nanoparticles by precipitation method. As a results of using sonochemistry for 20 minutes at 50% of power, 20 % of amplitude and 80% of cycles was possible to achieve a core shell structure, TEM results shown hexagonal shape nanoparticles with a dark core and a shell surrounding that core, verifying the coreshell structure. According to these results the next stage is to carry out the photocatalysis test at pH 7 to remove a textile dye expecting to have a good removal of it and a recovery of the catalyst by a magnetic field. 226 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-163 ] Graphene growth from a pattern of pencil drawn dots Juan Jesus Vivas Castro ([email protected]) 1 , Gabriela Lourdes Rueda Morales 1 , Jaime Ortiz Lopez 1 , Gerardo Ortega Cervantez 1 1 ESFM-IPN We present a simple, economical and efficient way to synthesize single and double layer graphene. Various patterns of equidistant dots were drawn with a commercial pencil on a Cu substrate. Substrates with pencil outlined patterns are heated for 15 minutes at 1050 ° C in a cylindrical oven under a flow of an Argon / Hydrogen gas mixture. From the results it was observed that the number of layers, coverage and structural quality of the synthesized graphene are closely related to the amount and distribution of the drawn patterns. The samples were characterized by scanning electron microscopy and Raman spectroscopy. Our findings show that graphite pencil lead can be used directly as a solid feedstock for high quality graphene growth. 227 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-170 ] Characterization and application of Au nanostructured substrates for surface enhanced Raman spectroscopy using Methylene blue as a test molecule. José Guadalupe Morales Méndez ([email protected]) 3 , Luis Escobar Alarcón 2 , Emmanuel Haro Poniatowski 1 1 1UAM- Izt Physics Department, San Rafael Atlixco No. 186, Col. Vicentina, Iztapalapa, 09340, Mexico 2 ININ, Carretera Mexico- Toluca s/ n, La Marquesa Ocoyoacac, Mexico 3 UAM- Izt Physics Department, San Rafael Atlixco No. 186, Col. Vicentina, Iztapalapa, 09340, Mexico The influence of the morphology and distribution of nano-structured gold substrates on the localized surface plasmon resonance wavelength and surface enhanced Raman signal (SERS) is investigated. The gold (Au) nanostructures are synthesized by laser ablation using a Nd: YAG laser emitting in the third harmonic, at a wavelength of 355 nm. Nanostructures are made by varying the number of pulses (600, 700, 800, 900, 1000, 1100, 1200, 1300, 1500, 5000) on the target. Typical pulse duration is 8 ns, the energy density is approximately 0.1 J/cm2. The gold nanostructures are characterized by UV- Vis spectroscopy. The surface plasmon wavelength shows a strong dependence on the nanostructures morphology which evolves progressively from nanospheres to more complex shapes. The SERS studies were performed using methylene blue as test molecule. It is found that the SERS signal exhibits a maximun depending on the surface morphology. [ NSN-171 ] Synthesis, characterization and matematicalmolecular modelling of silver NPs by photocatalytic reduction M. A. De la Cruz Garcia ([email protected]) 3 , M. A. Morales Sánchez 4 , E. Rubio Rosas 1 , J. Varela Caselis 1 , R. Agustín Serrano 1 , A. Maldonado 2 1 Centro Universitario de Vinculación y Transferencia de Tecnología, Benemérita Universidad Autónoma de Puebla, AV. San Claudio y Prolongación de la 24 sur, Col. San Manuel C.P. 72570, Puebla Pué. México. 2 Facultad de Ciencias Físico-Matemáticas, Benemérita Universidad Autónoma de Puebla, Av. San Claudio, Col. San Manuel, C.P. 72570, Puebla Pue. México. 3 Facultad de Ingeniería Química, Benemérita Universidad Autónoma de Puebla, Av. San 228 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla 4 Claudio, Col. San Manuel, C.P. 72570, Puebla Pué. México. Facultad de Ingeniería Química, Benemérita Universidad Autónoma de Puebla, Av. San Claudio,Col. San Manuel, C.P. 72570, Puebla Pué. México. Silver nanoparticles were synthetized by photo-reduction using silver nitrate (AgNO3), distilled water (H2O) and polyvinylpyrrolidone (PVP). The following solutions were prepared: a first solution (S1) of silver nitrate with distilled water to 0.01M, the second solution (S2) of silver nitrate, distilled water and polyvinylpyrrolidone to 0.1M, both solutions were irradiated by light UV with wavelength of 254 nm and exposition time of 40 and 80 minutes, respectively. The results obtained by Scanning Electronic Microscopy (SEM) showed cubic, thetrahedrical, and spherical morphologies for S1, and triangular morphology for S2. Two synthesis routes were employed: the one (S1) was realized with constant agitation, while in the second route over a substrate of SiO2 was synthesized silver nanostructures. The morphologies obtained, are particles with size of 50-100 nm, approximately. The analysis of X-Ray Diffraction showed the crystalline phases of metallic silver. We propose a photo-reaction mechanism which complemente the time-dependent Ginzburg-Landau equation with not conserved order parameter (TDGL), and it allowed us to simulate by computer the cubic morphology by adjusting control parameters such as temperature, chemical potential and mobility of the system, to understand the subjacent mechanism of growth and nucleation of silver nanoparticles. Keywords: Ginzburg-Landau equation, growth mechanism, coarsening 1. Sato-Berrúet, al., “Silver nanoparticles synthesized by direct photoreduction of metal salts. Application in surface-enhanced, Raman spectroscopy. 2009, 40, 376-380. 2. I. Ranvinoch, A. B. Ezersky, P. D. Weidman, The dinamics of patterns: World Scientific Publishing Co. Pte. Lid, 2000. 3. Richards, G. H. “Computational chemistry”. New York: Oxford University Press. 4. Witkowski, A. Tiribocchi, J. Stenhammar, R.J. Allen, D. Marenduzzol, M. E. Cates, “Scalar field theory for active particle phase separation”, Nature Communications. (2014) DOI: 10.1038/ncomms5351. 229 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-181 ] Anomalous Transport in PT-Symmetric Quarter Stacks Josué Ramírez Hernández ([email protected]) 2 , Felix Izrailev Mikhailovich 2 , Nykolay Makarov 1 1 Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Priv. 17 Norte No. 3417, Col. San Miguel Hueyotlipan, Puebla, Pue., 72050, México. 2 Instituto de Física de la Universidad Autónoma de Puebla, Apartado Postal J-48, Puebla, Pue., 72570, México. We studied the transmission and reflection properties for a stack of 𝑁 bilayers with PTsymmetry embedded in a homogeneous medium. Each (𝑎, 𝑏) bilayer is made of absorbing electromagnetic energy material (layer 𝑎) and amplifying material (layer 𝑏). The losses and gains are incorporated into the complex dielectric functions. They are balanced and their strength is defined by dimensionless parameter 𝛾. We have obtained a dispersion relation for the Bloch phase 𝜑𝐵 = 𝜅𝑑, which establishes the dependence of the Bloch wave number 𝜅 on the wave frequency 𝜔 and loss/gain parameter 𝛾. The spectral band/gap-structure appears only within an interval 0 < 𝛾 < 1. The number of spectral bands 𝑁𝑏 turns out to be finite and to depend on 𝛾: the larger the loss/gain parameter, the smaller the number of the spectral bands. We have reviled that there are two mechanisms for emerging the perfect transmission 𝑇𝑁 = 1 for a whole array of 𝑁 unit cells. The first one is the known Fabry-Perot resonances whose number depends on the number of unit cells 𝑁 and the loss/gain parameter 𝛾. The second mechanism is associated with two specific frequencies 𝜔𝑠𝑝 that separate the regions with 𝑇𝑁 < 1 from those with 𝑇𝑁 < 1 in every spectral band. We have recognized that, whereas 𝑇𝑁 (−𝛾) = 𝑇𝑁 (𝛾) , the left-hand and righthand reflectances are transformed one to another as the sign of 𝛾 is changed, 𝑅𝑁 (𝐿) (−𝛾) = 𝑅𝑁 (𝑅) (𝛾) . In addition, they obey the relation 𝑅𝑁 (𝐿) (𝛾) ≤ 𝑅𝑁 (𝑅) (𝛾) , being equal solely at the Fabry-Perot resonances. At specific frequencies 𝜔𝑠𝑝 the effect of unidirectional reflectionless emerges, where the perfect transmission 𝑇𝑁 = 1 takes place with vanishing only the left-hand reflectance 𝑅𝑁 (𝐿) (𝛾) = 0 . At the same time, the right-hand reflectance conserves its finite and positive value, 𝑅𝑁 (𝑅) (𝛾) > 0 . Our analytical findings are demonstrated by numerical data. 230 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-185 ] Pd content effect on the degradation efficiency in Pd/ZnO nanocomposites Ma. De Lourdes Ruiz Peralta ([email protected]) 2 , Gustavo Gonzalez Escobedo 2 , Alejandro Escobedo Morales 2 , J. Humberto Camacho García 2 , Jenaro Varela Caselis 1 1 Centro Universitario de Vinculación y Transferencia de Tecnología, Benemérita Universidad Autónoma de Puebla, C.P. 72570 Puebla, Pue., Mexico. 2 Facultad de Ingeniería Química, Benemérita Universidad Autónoma de Puebla, C.P. 72570 Puebla, Pue., Mexico. In the present work, Pd/ZnO nanocomposites with various palladium contents were prepared through hydrothermal method. The crystal structures, morphology and optical properties of the nanocomposites were characterized by X-ray diffraction (XRD), SEM, UVvis, Fast Fourier Infrared (FT-IR) and micro-Raman spectroscopies. Pd wt % were optimized to improve catalyst activity in the degradation of R6G used as a representative dye pollutant, the results demonstrate a degradation efficiency of 98.9% with a 1wt % of Palladium content.The pH value of the reaction mixture induces the formation of Pd or PdO nanoparticles,Raman spectra of Pd/ZnO nanocomposites show a broad band at 640 cm-1, attributed at PdO formation, however, the Raman spectra of the nanocomposites synthesized under acidic conditions shows a decrease in the intensity and a widening of the E2 (high) mode. 231 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-193 ] Carbon Nanotubes Synthesis by Chemical Vapor Deposition from Butanol, Diethyl Ether, Ethyl Acetate and Hexane Francisco Gabriel Granados Martínez ([email protected]) 3 , José de Jesús Contreras Navarrete 3 , Diana Litzajaya García Ruiz 3 , Carmen Judith Gutiérrez García 3 , Alejandro Durán Navarro 3 , Edgar Eduardo Gama Ortega 3 , Nelly Flores Ramírez 3 , Lada Domratcheva Lvova 3 , Leandro García González 1 , Luis Zamora Peredo 1 , María de Lourdes Mondragón Sánchez 2 1 Centro de Investigaciones en Micro y Nanotecnología Universidad Veracruzana Calzada Ruiz Cortines, 455, Costa Verde, 94294, Boca del Rio, Veracruz, México 2 Instituto Tecnológico de Morelia Av. Tecnológico 1500. Lomas de Santiaguito 58120, Morelia, Michoacán, México 3 Universidad Michoacana de San Nicolás de Hidalgo Gral. Francisco J. Múgica S/N, Felicitas del Río, 58030, Morelia, Michoacán, México Sustainability has become a main focus in the synthesis of CNTs. The use of low toxicity precursors has gain importance in order to reduce the environmental effects. The main object of this research is to develop alternatives to current used carbon precursors in the production of nanomaterials. Carbon nanotubes were produced via chemical vapor deposition (CVD) using as carbon source: butanol, diethyl ether, ethyl acetate and hexane. CVD was chosen due to its better yield attributes and the versatility on the exploitable precursors; additionally, it offers more control on the CNTs characteristics obtained. Argon was used as carrier gas at different flows ranging from 50-90 ml/min. Samples were synthesized in catalytic reaction using a quartz tube reactor and stainless steel AISI 304 core as catalyst support, at different temperatures between 680-850 ºC, according to the precursor. CNTs were characterized through Scanning Electron Microscopy (SEM), Energy Dispersed Spectroscopy (EDS), X-Ray Diffraction (XRD), Fourier Transformed Infrared Spectroscopy (FTIR) and Raman Spectroscopy. The SEM showed CNTs diameters from 50-300 nm. EDS analysis demonstrated carbon atomic percentages ranging from 93-99 %, 1.0-4.5 % iron and less than 1 % of manganese, chrome and silicon. FTIR confirms the presence of stretching vibrations containing CHx and C=C typical of aromatic rings. The research proposed innovating CNTs synthesis throught the use of some new carbon precursors and catalyst. With the acknowledgment for the support on this research to the CIC-UMSNH projects and the collaboration network of PRODEP “Nanostructural materials”. 232 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-205 ] MWCNTs oxidation by thermal treatment with air conditions Jose de Jesus Contreras Navarrete ([email protected]) 2 , Francisco Gabriel Granados Martínez 2 , Lada Domratcheva Lvova 2 , Nelly Flores Ramírez 2 , María Remedios Cisneros Magaña 2 , Leandro García González 3 , Luis Zamora Peredo 3 , María de Lourdes Mondragón Sánchez 1 1 2 Instituto Tecnológico de Morelia Universidad Michoacana de San Nicolás de Hidalgo 3 Universidad Veracruzana The incorporation of carbon nanotubes (CNTs) with several materials leads to new and innovating applications; generally, a process of functionalization has to occur to achieve the join. Nowadays the most different methods to add functionalized groups involve the use of acids. These techniques implicate high costs, laborious multistep process and environmental risks. The aim of this research was the oxidation of Multiwalled Carbon Nanotubes (MWCNTs) at atmospheric conditions through thermal treatment adding carbonyl groups. The MWCNTs were obtained by Chemical Vapor Deposition (CVD) at 760 °C using benzene and ferrocene as organic and organometallic precursors and argon as carrier gas. The MWCNTs were heated inside an electric furnace. Temperature ranged between 260 – 600 °C. The samples were characterized by Scanning Electron Microscopy (SEM), Energy Dispersed Spectroscopy (EDS), X-Ray Diffraction, Fourier Transformed Infrared Spectroscopy (FTIR) and Raman Spectroscopy. The results shown lost in weight percentage that fluctuated from 0 to 78 % according to different temperature conditions. The SEM micrographs indicated that MWCNTs remain below 400 °C. EDS analysis was focused in single CNTs and clusters. Carbon nanotubes without thermal treatment contain only carbon and iron; in contrast to the CNTs heated within air presence that showed up to 25 % oxygen. The larger oxygen amount was found on CNTs extremes and for iron was on base. FTIR analysis demonstrated presence of carbonyl groups and decrease of CHx. This research proposes one step functionalize process with low costs and environmental risks for carbonyl group CNTs. With the acknowledgment for the support on this research to the CIC-UMSNH projects and the collaboration network of PRODEP “Nanostructural materials”. 233 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-207 ] Optical properties of nanostructured bimetallic hyperbolic metamaterials Silvia Cortés-López ([email protected]) 1 , Felipe Pérez-Rodríguez 1 1 Instituto de Física, Benemérita Universidad Autónoma de Puebla, Apdo. Post. J-48, Puebla, Pue. 72570, México. The phenomenon of negative refraction, observed in metal-dielectric metamaterials, has been widely studied. This phenomenon can occur in double negative metamaterials, whose effective permittivity and permeability are simultaneously negative, or in strongly-chiral metal-dielectric structures. Such negative index metamaterials are fabricated by using different forms of the metal inclusions: split-ring resonators, dual-bar rods, fishnet structures, rotated crosses, and so on. Nevertheless, the negative refraction can also be observed in anisotropic media without requiring negative permeability nor strong chirality. For instance, a metal-dielectric superlattice possesses negative index of refraction in the frequency interval where the effective permittivity principal values, corresponding to the directions parallel and perpendicular to the plane of the layers, have opposite signs. In this work, we consider another type of superlattice, namely, a periodic heterostructure composed of two metallic layers in the unit cell. We have calculated the components of the average permittivity tensor in the long wavelength limit. Interestingly, the homogenized bimetallic superlattice behaves as a uniaxial crystal with different frequency-dependent permittivities along and across the periodicity direction. With these results, the reflectivity and transmissivity of a bimetallic multilayer structure have been calculated too. For p-polarized electromagnetic waves, it was found that both reflectivity and transmissivity exhibit Fabry-Perot resonances associated with the quantization of the wave vector. The resonances are observed in the frequency interval, where the refractive index is negative. We have analyzed the effect of both the bimetallicmetamaterial slab thickness and the angle of incidence on the optical spectra of reflectivity and transmissivity. This work was partially supported by VIEP-BUAP and CONACYT. 234 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-209 ] Spectroscopic Characterization of Calcined Zeolitic Tuff from Etla, Oaxaca-Mexico Manuel Sánchez Viveros ([email protected]) 4 , Gregorio Zacahua Tlacuatl ([email protected]) 4 , José Javier Castro Arellano 4 , Isaías Hernández Pérez 2 , Fernando Chávez Rivas 3 , Vitalii Petranovskii 1 1 Centro de Nanociencias y Nanotecnología, UNAM, C. P. 22860, Ensenada, B.C., México 2 Departamento de Ciencias Básicas, UAM-Azcapotzalco, C.P. 02200, México D. F., México 3 Departamento de Física, ESFM-IPN, C. P. 07738. México D.F., México 4 Laboratorio de Posgrado, ESIQIE-IPN. C. P. 07738, México D. F., México This work reports studies of the nature of iron oxide species in zeolitic tuff from Etla, Oaxaca, Méx. The zeolitic mineral has been grinding and calcined at 250 and 500 °C. The set of samples were analyzed XRD, UV-Vis and EPR. As a catalytic test we have employed the photo-catalytic degradation of Black 5 azo dye (RB5). By XRD technique was found an increase of the initial amorphous phase, with increasing calcinations temperature, and the analysis of selected diffraction lines and using the Debye-Scherrer function was found that the average grain decrease mainly to the clinoptilolite phase. The UV-vis results shows that the bands for λ > 650 nm decrease in intensity with the augmentation of the calcined temperature, and the opposite effect is observed on the bands in the range of 400 to 650 nm. Form EPR technique we have detected broad ferromagnetic signals characteristics of ironoxides nanoparticle, who´s intensity decrease with the calcinations temperature. Concerning to the catalytic activity was found that the samples calcined at 500 °C have a better photocatalytic in comparison with the lower and the uncalcined samples. We propose to the iron oxides nanoparticles as the sites of the photo-catalytic activity into the degradation of RB5. 235 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-225 ] Synthesis, characterization and simulation of ternary magnetic fluids whit magnetite nanoparticles Sergio Enrique Pichón Posada ([email protected]) 1 , Marco Antonio Morales Sánchez ([email protected]) 1 1 Benemérita Universidad Autónoma de Puebla (BUAP) Keywords: magnetic fluid, magnetic nanoparticles, Hele-Shaw cell, magnetite, magnetic field strength. In the present work was realized the synthesis of a magnetic fluid made of magnetite nanoparticles, these nanoparticles were suspended in oil and immersed in water with the aim of understand the behavior of the ternary mixture in the presence of magnetic fields and create a model mathematician to explain the mixture pattern formation. Magnetite nanoparticles were obtained by the precipitation method of ferric and ferrous salts in solutions of ammonium, obtaining nanoparticles of 70 nm. These nanoparticles were functionalized with a coupling agent (3-Glycidyloxypropyl trimethoxysilano) in order to generate a better compatibility and fluid dispersion. The nanoparticles were characterized by X-ray diffraction (XRD), infrared spectroscopy (FTIR), electron microscopy (SEM), atomic force microscopy (AFM) and to study the behavior of the magnetic fluid by optical microscopy. Finally, the computer simulation (using Fast Fourier Transform with programming language python and their libraryT-Kinter) of the mathematical model can to be controlled different parameters such as concentration of particle magnetic moments, magnetic field strength, temperature and chemical potential. The patterns obtained by this simulation are very similar to the behavior shown experimentally, confirming the accuracy of the mathematical model presented earlier. References: [1] M. A. Morales, J.F. Rojas: Modeling ternary mixtures by mean-fiel theory of polyelectrolytes: coupled Ginzburg-Landau and Swift-Hohenberg equations, Benemérita Universidad Autónoma de Puebla, Centro universitario de vinculación y transferencia tecnológica, Physica A 391 (2012) 779791. [2] P.e. Lloret, C.a. Moina, G.o. y barra: síntesis, funcionalización y caracterización de nanoparticulas magnéticas con estructura núcleo-cáscara, centro de investigación y desarrollo en electrodeposición y procesos superficiales. (7 de septiembre 2007). [3] Antonio Mora Rosas: Modelación y Simulación de Comportamientos No-lineales, en Física de Materiales, Química y Biomimética, Benemérita Universidad Autónoma de Puebla. Centro universitario de vinculación y transferencia tecnológica. Pág. 1-7. 236 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-279 ] Low-temperature thermal annealing of pure Zn nanostructures Roberto López ([email protected]) 1 , Enrique Vigueras 1 1 Laboratorio de Investigación y Desarrollo de Materiales Avanzados (LIDMA), Facultad de Química, Universidad Autónoma del Estado de México, Paseo Colón esquina Paseo Tollocan, Toluca Estado de México, México Metal Zn nanostructures were deposited by vacuum thermal evaporation and subsequently annealed in ambient atmosphere. The Zn nanostructures were deposited during 10, 30, or 60 min at a vacuum pressure of 10 -6 Torr. The nanostructures were then heated at 100 or 200 °C for several post-annealing times. Scanning electron microscope, energy dispersive spectroscopy, and X-ray diffraction under grazing incidence techniques were performed to evaluate the morphological and structural characteristics of the Zn nanostructures after the thermal annealing process. The nanostructures heated at 100 °C held similar morphological and structural characteristics compared to that of those as-deposited samples. However, annealing performed at 200 °C leads to the transformation of the structure and morphology, which changed the initial metal properties of the as-deposited nanostructures. 237 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-282 ] Growth of 4-aminothiophenol on iodine modified Au(100) studied by scanning tunneling microscopy Tizoc Fernando Huerta Garcia ([email protected]) 2 , José Valenzuela Benavides ([email protected]) 1 1 Centro de Nanociencias y Nanotecnología, Universidad Nacional Autónoma de México Km. 107 Carret. Tijuana-Ensenada, Ensenada, B.C., México c.p. 22860 2 Posgrado en Ciencia e Ingeniería de Materiales, U.N.A.M. Km. 107 Carret. TijuanaEnsenada, Ensenada, B.C., México c.p. 22860 Abstract: The presence of an adsorbed iodine layer on different crystallographic faces of noble metals can reduce the interaction strength between an adsorbed organic molecule and the metal substrate, permitting the weaker intermolecular interaction to become relevant thus resulting in long range order in self assembled molecular (SAM) layers. In this work, we describe the growth mechanism of 4-aminothiophenol (4-ATP) molecules on iodine modified Au(100), as studied by electrochemical scanning tunneling microscopy and cyclic voltammetry. The first stages of ATP adsorption is characterized by one dimensional molecular growth along well defined directions of the iodine monolayer, and long and thin trenches between molecular lines that are present even after several layers have grown. At more positive potentials complete surface coverage is observed on the surface. After returning the potential to more negative potentials, molecular desorption occurs and randomly distributed pits or vacancies appear on the surface. This markedly different desorption mechanism from the adsorption process is explained in terms of the different molecular bonds during the oxidation of the ATP molecule. Although 4-ATP oxidation and the formation of secondary products on a Au electrode is a rather well studied process, to our knowledge the present work represents the first attempt to understand the role of an iodine monolayer on the electrochemistry of ATP on Au(100) electrodes. Keywords: Scanning tunneling microscopy, electrochemical phenomena, gold, iodine, aminothiophenol 238 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-302 ] Adsorption of methylene blue dye onto multiwalled carbon nanotubes decorated with metal nanoparticles Julián López-Tinoco ([email protected]) 5 , Javier Lara-Romero 4 , Francisco Paraguay-Delgado 1 , Gabriel Alonso-Núñez 3 , Sergio JiménezSandoval 2 1 Centro de Investigación en Materiales Avanzados Unidad Chihuahua Centro de Investigación y de Estudios Avanzados del IPN Unidad Querétaro 3 Centro de Nanociencias y Nanotecnologia UNAM Ensenada 4 Facultad de Ingeniería Química-Universidad Michoacana de San Nicolás de Hidalgo 5 Universidad Politécnica de Lázaro Cárdenas 2 Synthetic dyes are extensively used as coloring agents in textile, paper, pharmaceutical and food industries. Water contamination with these synthetic dyes is a serious environmental problem. In this work we evaluate the adsorption capabilities of ceria and zirconia nanoparticles deposited on multiwalled carbon nanotubes as an alternative to the adsorption of dyes. The dye used in this study was the basic blue 9 (Methylene Blue). The adsorption studies were carried out using UV-Vis spectroscopy. It was found that carbon nanotubes with ceria and zirconia nanoparticles have a greater adsorption capacity compared to functionalized CNTs. For the synthesis of the metal nanoparticles, metal nitrates were used as metal sources, dioctil sodium sulfosuccinate (AOT) was used as surfactant and NaBH4 was used as a reducing agent. The synthesis was performed at 120°C, 10 minutes and 600 W. Carbon nanotubes multiwalled were synthesized by the spray pyrolysis method using alpha-pinene as a carbon source and ferrocene as catalyst. CNTs were purified and functionalized by a conventional acid treatment. The materials produced were characterized by transmission electron microscope of high resolution (HR-TEM), Raman spectroscopy, thermal gravimetric analysis (TGA) and X-ray diffraction (XRD). 239 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-304 ] Optical properties for dielectric-graphenedielectric multilayer quasi-periodic Thue-Morse Structure Ireri Aydee Sustaita-Torres ([email protected]) 2 , Claudia Sifuentes-Gallardo 2 , Raúl Alberto Reyes-Villagrana 1 , Isaac RodríguezVargas 1 , Jesús Madrigal-Melchor ([email protected]) 1 1 ) Unidad Académica de Física, Universidad Autónoma de Zacatecas, 98060, Zacatecas, México. 2 Unidad Académica de Ingeniería Eléctrica, Universidad Autónoma de Zacatecas, 98000, Zacatecas, México. Potential applications in optoelectronics had generated a great interest of study of graphene optical properties. Along with this, the graphene have exceptional properties such as high mobility and optical transparency, flexibility, robustness. Is for this properties of graphene can be used in different devices such as transparent conductors, organic light-emitting diodes, photodetectors, touch screens, saturable absorbers and ultrafast lasers [1]. A transfer matrix method (like Pochi-Yeh) is developed for obtained optical properties, reflection, transmission, and absorption in the far-infrared region. The quasi-periodic structure was compound by intercalate graphene sheets between two consecutives dielectrics, and the dielectrics media follows Thue-Morse sequence. The graphene sheets was described by the optical conductivity considering interband and intraband transitions [2]. The structure of the spectra depends, in far infrared region, strongly of the number of sequence generation, width of the different dielectrics and optical contrast (dielectric contrasts). The results for transverse magnetic polarization and transverse electric polarization for different angles are shown. In spectra the geometrical properties of the sequence Thue-Morse can be observed and obtain absorption band well define. We had made a comparison between quasi-regular and regular structures. [1] F. Bonaccorso, Z. Sun, T. Hasan and A. C. Ferrari, optoelectronics, Nature Photonics, 4 611-622, sep. (2010). Graphene photonics and [2] L. A. Falkovsky and S. S. Pershoguba, Optical far-infrared properties of a graphene monolayer and multilayer, Phys. Rev. B 76, 153410 (2007). 240 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-319 ] Different routes to prepare MoS2 nanofibers by electrospinning, for applications in lithium ion batteries. Nadia Cruz Gonzalez ([email protected]) 1 , Miguel Angel Melendez Lira 1 1 Department of Physics, CINVESTAV-IPN, Av. Instituto Politécnico Nacional 2508, col. San Pedro Zacatenco, Delegación Gustavo A. Madero, México D.F. C.P. 07360 Recently, energy problem has become the greatest problems and attracted worldwide attention. It has been proved to be an important task for scientist to search new materials possessing great performances in dealing with the energy conversion, storage and usage. Super capacitor is a new energy storage device, and it has many advantages such as long service life, great power density, high energy density, green environmental protection and has attracted enormous research interest. In recent years materials based on metal dichalcogenides layered (MDL) has been used in anodes for the second generation of rechargeable lithium batteries (LIBs) for its similar properties of graphene. The super capacitor performance of MoS2 is comparable to those carbon nanotube array electrodes. However, the electronic conductivity of MoS2 is still lower compared to graphite / graphene, and the specific capacitance of MoS2 is still very limited in alone for energy storage applications. Nanofibers-LMD / potentiate chemical and electrical properties of both materials that absorb volume expansion in the loading / unloading, improving structural stability and cyclability of the electrodes. This paper describes tow procedures of synthesizing MoS2 nanofibers. In First method Polyvinylpyrrolidone (PVP)/Ammonium tetrathiomolybdate (ATTM) composite nanofibers were prepared by a sol–gel method and an electrospinning technique. Subsequently, the MoS2 nanofibers were derived from reduction of these precursor composite fibers at 450 °C under a H2 atmosphere for 2 h, and annealed under Ar atmosphere for 6 h. In Second Method, PVP nanofibers and MoS2 nanoribbons were synthetized bye electrospinning and solvothermal techniques. The composite nanofibers were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). This work was financed by CONACYT project number CB2010-154857 and CONACYT postdoctoral fellow second call 2014, Referencia: CVU No.218308. 241 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-324 ] Fractal graphene systems: Combined effects of magnetic and electric fields on the transmission, transport and electronic structure characteristics Rogelio Rodríguez González ([email protected]) 1 , Isaac Rodríguez Vargas 1 1 Unidad Académica de Física, Universidad Autónoma de Zacatecas, Calzada Solidaridad Esquina Con Paseo La Bufa S/N, 98060 Zacatecas, Zac., México. We investigate the tunneling peculiarities of massive Dirac electrons through magnetoelectric fractal graphene barriers. To this aim, the transmittance, linear-regime conductance and spectrum of bound state are calculated. For the magnetoelectric fractal barriers the electric and magnetic fields are considered along with a non-periodic order of Cantor kind for the spatial distribution of the barriers. With this in mind, we compare the above physical properties between systems of electric, magnetic and magnetoelectric barriers. Our results indicate that the magnetoelectric barriers together with the aperiodic order can modulate in an effective way the transmission, transport and electronic structure characteristics. 242 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-364 ] Electrical transport properties of selfAssembled ZnO nanoparticles embedded in a silicon oxide matrix produced by reactive RF sputtering.* P.R. Jiménez-Macías 1 , A. Lara-Sánchez 5 , A. Hernández-Hernández 4 , A. García-Sotelo 3 , E. Campos 3 , S. Gallardo-Hernandez 3 , M. Zapata-Torres 2 , J.L. Fernández-Muñoz 2 , E. Valaguez-Velazquez 6 , M. Melendez-Lira ([email protected]) 1 1 1Departamento de Física, CINVESTAV-IPN, , Apdo. Postal 14-740, 07000, México DF CICATA-IPN, Unidad Legaria, Calz. Legaria 694, Col. Irrigación, 11500, Mexico, DF 3 Departamento de Física, CINVESTAV-IPN, , Apdo. Postal 14-740, 07000, México, DF 4 Escuela Superior de Apan, Universidad Autónoma del Estado de Hidalgo, Calle Ejido de Chimalpa Tlalayote S/N Col. Chimalpa, Apan, Hidalgo. México 5 Facultad de Ingeniería, Universidad Autónoma de Chihuahua, México, 6 UPIITA-IPN Av. IPN 2580, C.P. 07340 México, DF 2 Self-assembled silicon and germanium nanoparticles embedded within a SiO2 matrix have been successfully produced taking advantage of the roughness associated with the sputtering deposition process[1,2]. The aforementioned approach has been employed to explore the possibility to produce ZnO nanoparticles embedded within a silicon oxide matrix on soda-lime glass and p-silicon substrates. Silicon dioxide and metallic Zn films were deposited employing silicon and zinc targets. Oxygen content of the working plasma was modulated through argon partial pressure. X-ray diffraction characterization do not shown the presence of metallic zinc. Secondary ion mass spectroscopy shown an interdifussion of zinc throughout the SiO2 matrix. TEM micrographs indicated the presence of nanoparticles. XPS shown ZnO formation under specific growth parameters. Photoluminescence emission at room temperature for samples grown on silicon substrates was not observed. Transport properties were studied measuring the IvsV characteristics of the films. For samples grown on silicon rectifying behavior and spectral response are observed . The observed results of transport properties are discussed in terms of the crystalline structure of the ZnO nanoparticles and its interaction with SiO2 matrix. *: Partially funded by CONACyT-Mexico [1]. Mota-Pineda, E., et al. Journal of Applied Physics 108.9 (2010): 094323. [2] Hernández-Hernández, A., et al. Journal of Applied Physics 111.4 (2012): 044327. 243 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-366 ] Nucleation and growth of eutectic nanopowders: a re-engineering approach H. Rojas-Chávez ([email protected]) 3 , D.A. Mora-Alvarado 3 , M.L. Mondragón-Sánchez 2 , C. Flores-Morales 4 , D. Jaramillo-Vigueras 1 1 Centro de Investigación e Innovación Tecnológica - IPN 2 Instituto Tecnológico de Morelia - TecNM 3 Instituto Tecnológico de Tláhuac II - TecNM 4 Instituto de Investigaciones en Materiales - UNAM We report the mechanosynthesis of Pb0.26Sn0.74 nanoparticles using high-energy milling process under composition, pressure and temperature (C-P-T) vial conditions. A eutectic alloy was obtained by mechanosynthesis from elemental powders of Pb and Sn via high-energy milling under controlled C-P-T vial conditions. Systematic analysis of transformation in the resulting phases of milling has been envisaged to characterize microstructures i.e. morphology, particle size and percentage of different phases formed as a function of milling time. As-milled powders were analyzed by Atomic Force Microscopy, X-ray powder diffraction and crystals structures were refined by the Rietveld method. The results reveal that the system of Pb-Sn powders transforms gradually to eutectic alloy, Pb0.26Sn0.74. The difficulties in using the conventional process (melting/solidification) for producing eutectic alloys lie in certain aspects. First, the temperature is usually quite high, which could cause the oxidation of samples according to the Gibbs free energy criteria. Second, the poor mixing in the liquid zone promotes segregation in melted alloys. The third problem is that the conventional process use vacuum conditions and the surface oxides in melted alloys have to be reduced by molecular hydrogen. So, this process is expensive compared with the proposed one. In order to overcome these difficulties, we suggest a non-equilibrium process as follows: this process utilizes an equivalent energy in order to ensure a free-impurities stoichiometric eutectic alloy. Moreover, an inert experimental setup and a high-energy mechanical source are suggested. Re-engineering of eutectic alloys obtained by a nonequilibrium process to fully avoid thermal energy sources is proposed in this work. 244 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-388 ] Incorporation of ZnO Nanostructures in a MIS Diode Architecture Rubén Jonatan Aranda García ([email protected]) 1 , Daniel Valdivia Montes 2 , Alejandro Escobedo Morales ([email protected]) 2 , Jose Alberto Luna López 1 , José Antonio Rivera Márquez 2 1 Centro de Investigación en Dispositivos Semiconductores-ICUAP, Benemérita Universidad Autónoma de Puebla, Puebla, Pue., Mexico 2 Facultad de Ingeniería Química, Benemérita Universidad Autónoma de Puebla, Puebla, Pue., Mexico Because of its physical properties, ZnO is considered a potential semiconductor compound for fabricating electronic and optoelectronic devices. In this regard, several growth techniques have been developed to ensure the required control for manufacturing commercial devices. On the pathway for improving the performance of the actual devices, lowdimensional materials seem to be a promising alternative. Here, the fabrication of a metal-insulator-semiconductor (MIS) diode structure based on ZnO nanostructures is reported. The ZnO nanostructures were grown on anodized aluminum substrates (Al2O3/Al). While the ZnO nanostructures were obtained through a lowtemperature hydrothermal route, the substrates were prepared by subsequent electrochemical processes: electropolishing (4V; 8 min) and anodizing (1 mA; 2 min). The ZnO/Al2O3/Al architecture was studied by x-ray diffraction (XRD), scanning electron microscopy/energy dispersive x-ray spectroscopy (SEM/EDS) and impedance measurements. The voltage-time data (anodizing) and the capacitance values indicate the formation of an insulating barrier (Al2O3) on the metallic substrate (Al); this was confirmed by means of SEM and EDS analysis. Our studies show that the reported method is effective for growing ZnO nanorods whose dimensions are about a hundred nanometers- on anodized aluminum substrates in order to obtain a MIS diode structure. The ZnO nanostructures have preferred orientation, presumably along the [001] direction as their crystal habit suggests. 245 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-389 ] Physical and magnetic properties of nanostructured Gd-Fe3O4 cores obtained by coprecipitation Sandra Irene Eguía Eguía ([email protected]) 2 , Angel Guillén Cervantes 1 , Jaime Santoyo Salazar 1 1 2 Departamento de Física, CINVESTAV Zacatenco, México, D.F. Doctorado en Nanociencias y Nanotecnología, CINVESTAV Zacatenco, México, D.F. Nowadays, iron oxides doped with Gd nanoparticles have been investigated due to their superparamagnetic properties as directional magnetic core in bio-medical applications. The main challenge is synthesize Gd-Fe3O4 nanoparticles with magnetic monodomains and uniaxial anisotropy with low remanence energy. These features allow getting specific control over magnetic response and biodistribution for future applications as functionalized systems in nanomedicine. In this work, we show preliminary results of the synthesis of Gd-Fe3O4 nanoparticles via co-precipitation of aqueous solutions of ferrous and ferric chloride salts. The as-synthesized powders were characterized by different techniques. Size, morphology and composition of the nanoparticles were determined by transmission electron microscopy (TEM), scanning electron microscopy (SEM); and energy-dispersive x-ray spectroscopy (EDS), while the structure of the as-synthesized nanoparticles was identified by x-ray diffraction (XRD) and, Fourier transform infrared (FT-IR). Finally, these results are correlated with magnetic responses and magnetic domains interactions measured by magnetometer and magnetic force microscopy (MFM) to consider the Gd-Fe3O4 as candidate for contrast agent and hyperthermia treatment applications. 246 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-399 ] Magnetic properties of nanostructured MBE grown (GaMn)As Antonio Del Rio De Santiago ([email protected]) 1 , Esteban Cruz Hernandez 1 , Cesar Fidel Sanchez Valdes 2 , Jose Luis Sanchez Llamazares 3 , Isaac Martinez Veliz 4 , Maximo Lopez Lopez 4 , Victor Hugo Mendez Garcia 1 1 Center for the Innovation and Application of Science and Technology (CIACyT), Universidad Autónoma de San Luis Potosí, Av. Sierra Leona #550, Lomas 2a Secc., San Luis Potosí, S. L. P. 78210, México. 2 CNyN, UNAM, AP 14, Ensenada 22860, Baja California, México. 3 Instituto Potosino de Investigación Científica y Tecnológica A.C., Camino a la Presa San José 2055, Col. Lomas 4ª sección,San Luis Potosí, S.L.P. 78216, México. 4 Physics Department, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal 14-740, México D.F. 07000, México. The growth a semiconductor materials that sustain ferromagnetic properties at room temperature have been the target of numerous studies since the Mid-20th century. The importance of these systems lays on their potential applications in areas such as quantum computing, spintronics and novel solar cells. The most promising materials among dilute magnetic semiconductors (DMS) to realize these applications is the GaAs doped with Mn. Typically, the (GaMn)As films are grown by molecular beam epitaxy (MBE) at low temperature (LT) (<290°C), due to the fact that the solubility of Mn in GaAs is very low at thermal equilibrium, so that (GaMn)As is a metastable compound which can only be grown with low temperature MBE far from thermal equilibrium. However, LT-MBE has several disadvantages, such as high concentration of vacancies, interstitial Mn and As antisities. Most of these factors limit the ferromagnetic transition temperature below 177K [1]. In this work in order to avoid the above mentioned defects, we grew (GaMn)As by MBE at high temperature, 530 ° C. By using a vibrating sample magnetometer, hysteresis loops in the range of temperature from 3 and 400 K were obtained. The remanent field shows ferromagnetism above room temperature for samples grown at the Mn concentration, Mn%, of 0.02 to 0.2. The coercive field at RT, Hc, increases from 52.85 to 356 Oe as Mn% increases. The remanent magnetization, M, shows a similar dependence with Mn%: it steadily changes from 0.87×10-6 to 3.71×10-6 emu. However, for samples Mn%=0.02 and 0.04%, dissimilar magnetic properties dependence was found. This is explained in terms of differences in crystalline quality for these samples as corroborated by high resolution X-ray diffraction. To be sure of the fact that the manganese is integrated in the whole layer, secondary ion mass spectrometry (SIMS) depth profiles were obtained. The SIMS analysis indicates that, though the Mn% incorporation was not uniform, the dopant is integrated into the entire layer. [1] H. Ohno, A. Shen, F. Matsukura, A. Oiwa, A. Endo, S. Katsumoto, Y. Iye, Appl.Phys. Lett. 69 (1996) 363. Acknowledgments: The author acknowledges the financial support of CONACYT, CeMIE-SOL 22, FRCUASLP, INFR-2015-01: 255489, PNCPN2014-01: 248071, and CB: 168761. 247 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-409 ] Mn incorporation in GaAs grown by HTMBE studied by SIMS and HRXRD Estebán Cruz Hernández ([email protected]) 1 , Antonio Del Río De Santiago 1 , Salvador Gallardo Hernández 2 , Miguel Angel Vidal Borbolla 1 , José Angel Espinoza Figueroa 1 , Manuel Gutiérrez Hernández 1 , Máximo López López 2 , Víctor Hugo Méndez García 1 1 CIACyT, Universidad Autónoma de San Luis Potosí 2 Departamento de Física, CINVESTAV Diluted Magnetic semiconductors (DMS) has received much attention in recent years due to the interest in the integration of ferrogmanetism and spin-electronics with the ubiquitous semiconductor technology [1]. In particular, the growth of the DMS GaMnAs exhibiting high crystalline quality is of special interest to the incorporation of ferromagnetic GaMnAs layers into the GaAs-based microelectronic and optoelectronic devices. However, these potential applications has been limited because GaMnAs with useful Mn atomic percent (Mn%) high concentration is only obtained by growing at low-temperature (< 300 °C), which cause a poor GaMnAs crystallinity as compared with GaAs grown at higher temperatures (>500 °C). In this work we investigate the mechanisms of the Mn incorporation in GaAs by growing by MBE at the relative high temperature of 530 °C. The samples were grown by varying the nominal Mn% from 0.01 to 0.2. From AFM and SEM imaging we found the formation of nanostructures at the top of an initial layer of GaMnAs for the higher Mn% concentrations. For Mn% < 0.1, nor any formation of surface structures was found. By SIMS analysis variations in the Mn gradient concentration were obtained, which strongly depends on the Mn% and the formation of the nanostructures. HDXRD rocking curves shows good crystallinity and the apparition of MnAs aggregates in the sample with the higher Mn% concentration. *Corresponding author: [email protected] [1] Rev. Mod. Phys., Vol. 86, No. 1, (2014) Acknowledgments: The author acknowledges the financial support of CONACYT, CeMIESOL 22, FRC-UASLP, INFR-2015-01: 255489, PNCPN2014-01: 248071, and CB: 168761. 248 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-410 ] Influence of Dy doping on structural and optical properties of ZnO nanostructures Raul Sanchez Zeferino ([email protected]) 1 , Gemma Moreno Corella 2 , Mario Enrique Álvarez Ramos 1 , Javier Hernández Paredes 1 1 Departamento de Física, Universidad de Sonora, Blvd. Luis Encinas J y Rosales S/N Col. Centro, Hermosillo, Sonora C.P. 83000, México. 2 Posgrado en nanotecnología, Universidad de Sonora, Blvd. Luis Encinas J y Rosales S/N Col. Centro, Hermosillo, Sonora C.P. 83000, México. The study of the optical properties of ZnO is an important research for practical applications such as solar cell, gas sensors, white light emitting, optoelectronic devices, etc. Using sonochemical synthesis, undoped ZnO and Dy-doped ZnO 1-4 mol % nanoparticles were prepared. The aim of this work is to analyze the optical properties of ZnO nanostructures for possible application in white light emitting devices. Scanning electron microscopy (SEM) showed that undoped ZnO nanostructures have an undefined morphology, however, for the Dy-doped ZnO nanostructures present a formation of leaves or flakes type morphology. Patterns of X-ray diffraction (XRD) showed peaks assigned to the hexagonal wurtzite type structure of ZnO in the case of heat-treated samples at 700 °C and majority phases of zinc hydroxide for ZnO powders without annealing. The main vibrational modes of ZnO were found in the Raman spectra performed on samples with annealing, however, for the samples without annealing mainly phases of zinc hydroxide were found, it is consistent with the results of XRD. The UV-Vis spectra exhibit an absorption edge around 383 nm which is characteristic of ZnO. All the photoluminescence spectra (PL) of ZnO and ZnO: Dy nanostructures showed two emission bands. A PL peak at approximately 383 nm and a broad emission band between 400 and 800 nm. The results showed that the emission from the sample without annealing and doped with Dy 2 mol % is the closest to the white light emission. Several significant changes in the properties of ZnO:Dy were observed due to the variation of doping and the application of annealing which are discussed in detail in this research. 249 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-419 ] Effect of the applied external magnetic field in the density of interfacial traps in nanometer transistors Hector Manuel Uribe Vargas ([email protected]) 1 , Joel Molina Reyes 1 1 INAOE As the dimension of advanced electronic devices reach nanometric scales, high-k materials are used as gate oxides in state-of-the-art Complementary Metal-Oxide-Semiconductor (CMOS) devices. These oxides have allowed Moore´s law to continue, nevertheless, the interface between high-k oxides and silicon does nos have good quality, thus reducing the mobility of the electrons in the channnel, so its important to measure the denisty of interface traps in these devices. One often used technique to measure the interface trap density is C-V, altough this technique can not be implemented in ultra-thin high k- oxides (<4nm). One alternative is the charge pumping technique, which we used in this work. In this work, 28nm IBM transistors were electrically charachterized (Id-Vg, Id-Vd, Vth, Vfb) and using the charge pumping technique, Dit was measured in these devices. Then, an external magnetic field perpendicular to the channel is applied, thus modulating the Dit. 250 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-432 ] Green synthesis of silver and gold nanoparticles by aquoethanolic extract of Bacopa procumbens (Mill.) Valentin Lopez Gayou ([email protected]) 1 , Juan Manuel Castelan Figueroa 1 , Elias Emilio Hernandez Beteta 1 , Marlon Rojas Lopez 1 , Alejandro Zamilpa 2 , Blanca Eda Dominguez Mendoza 3 , David Guillermo Perez Ishiwara 1 1 2 CIBA-IPN, Tlaxcala, 90700, Mexico CIBIS-IMSS. Argentina No. 1, Col. Centro, Xochitepec, Morelos C.P. 62790, México 3 Laboratorio de RMN, CIQ-UAEM, Av. Universidad 1001. Colonia Chamilpa, Cuernavaca, Morelos C.P. 62210, México The need to fabricate nanostructured materials has led us to seek ecological methods that allow us to care for our environment and reduce costs. In recent years, the green synthesis show good results in the obtaining of metal nanoparticles as a quick, efficient, cheap and ecofriendly process. The use of plant extracts gained importance because of the simplicity by eliminating the elaborate process of maintaining cell cultures and eco-friendliness used in bacteria and fungi have also been utilized in the synthesis of nanoparticles. We has been observed that various metabolites in plant extracts have the ability to reduce silver and gold ions acting as chelating and stabilizers agents of nanoparticles, increasing the biocompatibility. In this study uses the aquoethanolic extract of Bacopa procumbes as reducing and stabilizer agent for obtaining gold and silver nanoparticles. The formation of nanoparticles was by UV-vis spectroscopy and the functional groups on the surface of the nanoparticles was analyzing by FTIR. The size and morphology was observed by transmission electron microscopy (TEM). 251 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-437 ] Study of low temperature photoluminescence in ZnS:Mn2+ nanoclusters María del Pilar Gutiérrez Amador ([email protected]) 2 , Arturo Hernández Hernández 2 , Betsabée Marel Monroy Peláez 3 , Jaime Santoyo Salazar 1 1 Departamento de Física, CINVESTAV-IPN, Apdo. Postal 14-740, 07000, México D.F., México. 2 Escuela Superior de Apan, UAEH, Carretera Apan- Calpulalpan km 8, Apan, Hgo. 43920 México. 3 Instituto de Investigaciones en Materiales-UNAM, Apdo. Postal 70-360, México D.F., Coyoacán 04510, México. Undoped and Mn-doped ZnS nanoclusters have been synthesized by a soft chemistry method [Zn(1-x)MnxS (0.010≤x≤0.20)]. The average size of nanoclusters is in the range of 3 to 5 nm in cubic blenda structure. The band gap value decreased from 3.58 eV (for x=0) to 3.24 eV as a function of mangenese content. The samples with manganese content between 0.05 and 0.15 showed the photoluminescence effect. For higher manganese concentrations this phenomenon disappears. The PL spectra of Mn-doped ZnS nanoclusters at room temperature exhibit two emission bands, the 495 nm blue emission host defect-related and the orange 588 nm emission associated with the 4T1-6A1 transition of Mn2+. The blue emission is dominant at low temperatures (from 10K to 200K) ; while the orange emission is dominant in the range of 200 K to room temperature. An energy levels scheme is proposed in order to explain the photoluminescence behavior of the Mn-doped ZnS nanoclusters. 252 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-440 ] Thermodynamic approach in formation of Ge nanocrystals on silicon oxide through crystallization and agglomeration from amorphous thin films. Arturo Hernández-Hernandez ([email protected]) 3 , Luis Alberto Hernández-Hernández 4 , Francisco De Moure-Flores 5 , José Guadalupe Quiñones-Galván 1 , Miguel Meléndez-Lira 2 1 Departamento de Física, CUCEI, Universidad de Guadalajara, Blvd. M. García Barragán 1421, Guadalajara, 44430, Jal, México C.P. 44430 2 Departamento de Física, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, A.P. 14740, C.P. 07300, México, Distrito Federal, México. 3 Escuela Superior de Apan, Universidad Autónoma del Estado de Hidalgo, Calle Ejido de Chimalpa Tlalayote s/n Colonia Chimalpa, Apan Hidalgo, México. 4 Escuela Superior de Física y Matemáticas del Instituto Politécnico Nacional, Edificio 9 U.P. Adolfo López Mateos, Col. San Pedro Zacatenco, C.P. 07730 México DF, México. 5 Facultad de Química Materiales, Universidad Autónoma de Querétaro, Querétaro, 76010, México. The crystallization process was examined for thin films of germanium on silicon oxide thin films (SiO2) grown by RF sputtering. Three-dimensional crystalline islands were formed through crystallization and agglomeration. The mechanism of germanium nanocrystals (GeNCs) formation was discussed on the basis of thermodynamics. In studying the crystallization of the germanium nanocrystals, the influence of the film-substrate interfacial energy and surfaces defects should be taken into consideration. It was found that the thickness of the as deposited amorphous films is an essential factor in determining the crystallization behavior and in controlling crystal size. 253 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-442 ] Enhanced Photoresponse of a Metal-OxideSemiconductor Photodetector with Germanium Nanocrystals Embedded in the Silicon Oxide Layer Arturo Hernández-Hernández ([email protected]) 3 , Luis Alberto Hernández-Hernández 4 , Francisco De Moure-Flores 5 , José Guadalupe Quiñones-Galván 1 , Betsabee Marel Monroy 6 , Guillermo SantanaRodríguez 6 , Miguel Meléndez-Lira 2 1 Departamento de Física, CUCEI, Universidad de Guadalajara, Blvd. M. García Barragán 1421, Guadalajara, 44430, Jal, México C.P. 44430 2 Departamento de Física, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, A.P. 14740, C.P. 07300, México, Distrito Federal, México. 3 Escuela Superior de Apan, Universidad Autónoma del Estado de Hidalgo, Calle Ejido de Chimalpa Tlalayote s/n Colonia Chimalpa, Apan Hidalgo, México. 4 Escuela Superior de Física y Matemáticas del Instituto Politécnico Nacional, Edificio 9 U.P. Adolfo López Mateos, Col. San Pedro Zacatenco, C.P. 07730 México DF, México. 5 Facultad de Química Materiales, Universidad Autónoma de Querétaro, Querétaro, 76010, México. 6 Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, A. P. 70-360, C.P.04510, Coyoacán, México DF, México. In this work we report a two-terminal metal-oxide-semiconductor photodetector for which light is absorbed in a capping layer of germanium nanocrystals embedded in a silicon oxide matrix grown on p -type silicon substrates. Operated at direct and reverse bias photoresponse from 900 to 1300 nm was observed. Also, we report on the effect of nanocrystal size on the photocurrent. The highest optoelectronic conversion efficiency was observed in samples with smaller germanium nanocrystals. This effect were explained by a transistorlike mechanism, in which the inversion layer acts as the emitter and trapped positive charges in the dielectric layer assist carrier injection from the inversion layer to the contact, such that the primary photocurrent could be amplified. 254 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-445 ] Optical Properties And Morphology of InAs Quantum Dots and Quantum Dashes Grown by MBE. Eric Eugenio López ([email protected]) 1 , Satoshi Shimomura 2 , Víctor Hugo Méndez García ([email protected]) 1 1 Center for the Innovation and Application of Science and Technology (CIACyT), Universidad Autónoma de San Luis Potosí, Av. Sierra Leona #550, Lomas 2a Sección, SLP 78210, México. 2 Graduate School of Science and Engineering, Ehime University, Bunkyo-cho 3, Matsuyama, Ehime 790-8577, Japan. The study of semiconductor quantum dot structures (QDs) is based on improving the control of the nucleation and to propitiate the self-ordering. This offers the possibility for developing new generation optical and electronic devices of high performance, taking advantage of their unique atomlike properties. Nevertheless, despite of their importance, there is still some lack of information in the self-ordering or nucleation on anisotropic high index substrates (AHIS). In this work, we studied the morphological and optical properties of self-organized QDs of InAs/GaAs grown by molecular beam epitaxy (MBE) on GaAs (411)B, (221)B and (100) substrates under different As pressures (P As=3.1, 4.5 and 6.0x10-6 mbar). Elongated structures, frequently termed as quantum dashes (QDHs) were observed by atomic force microscopy (AFM) for the samples grown on GaAs (221)B. The QDHs are oriented along [110]. It is thought that prior to the arrival of the In atoms, the GaAs(221)B surface was composed by facets naturally self-assembled along that direction [1]. The QDHs length increases with PAs, however at high PAs surface pits with a density of ~2x109 pits/cm2 appeared. For the samples grown on the (411)B and (100) surfaces bimodal size distribution of the QDs were observed. Clearly the density of the QDs varies as a function of PAs: for the large QDs on (411)B, slightly increases 2.2 to 3.2x1010 dots/cm2 while the small islands decreases from 3.4 to 1.1x1011 dots/cm2 when increasing PAs. For (100) samples the density of the small islands, behaves similarly, decreasing from 4 to 0.3x1011 dots/cm2 and the large QDs did not change with PAs (~4x1010 dots/cm2), but their average diameter did. The uncompensated evaporation of As due to the high growth temperature of the BL may have propitiated Ga droplets that acted as nucleation centers and therefore the high density of QDs. The PAs increment reduces the adatoms diffusion length [2] indicating the formation of large width InAs islands, as corroborated by AFM. The QDs emission on the (411)B samples as measured by photoluminescence spectroscopy blueshifted, which was related to alloying effects during the capping procedure. [1] F. Grosse, Phys. Rev. Letts., 89, 116102 (2002). [2] K. Stiles, J. Vac. Sci. & Tech. B, 3, 1089 (1985). The author acknowledges the financial support of CONACYT, CeMIE-SOL 22, FRCUASLP, INFR2015-01: 255489 and PNCPN2014-01: 248071. 255 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-493 ] Effect of the Energy Fluence on the Optical and Structural Properties of ZnO Nanoparticles Synthesized by Laser Ablation of Solids in Liquids Yryx Yanet Luna Palacios ([email protected]) 3 , Marco Antonio Camacho López 3 , Miguel Ángel Camacho López 2 , Guillermo Aguilar 1 1 Department of Mechanical Engineering, University of California Riverside, 900 University Ave., Bourns Hall A-341, Riverside, CA, USA. 92521. 2 Laboratorio de Fotomedicina, Biofotónica y Espectroscopia Láser de Pulsos Ultracortos, Facultad de Medicina, Universidad Autónoma del Estado de México, Jesús Carranza y Paseo Tollocan s/n. Toluca, México, C.P. 50120 3 Laboratorio de Investigación y Desarrollo de Materiales Avanzados, Facultad de Química Universidad Autónoma del Estado de México, Campus Rosedal, Km 14.5 Carretera Toluca-Atlacomulco, San Cayetano de Morelos, C.P. 50925 In recent years, Zinc Oxide Nanoparticles (ZnO NPs) have been very important due to their many applications, for example: solar cells, sunscreens, biosensors due to their optical properties, and even in biomedicine for cancer cell destruction. The optical and structural properties of ZnO NPs depend on the synthesis conditions. Mostly these ZnO NPs are synthesized by chemical methods, however this method provides contaminated ZnO NPs. On the other hand a physical method such as the Laser Ablation of Solids in Liquids (LASL) allows to have ZnO NPs free of contaminants and easy modification in the synthesis parameters, producing ZnO NPs with different optical and structural characteristics. In this work, we prepared ZnO NPs by LASL at different energy laser fluences. For the synthesis, we used a pulsed nanosecond Nd-YAG laser with a wavelength of 532 nm, a repetition rate frequency of 15 Hz and a per pulse energy of 25 mJ, three different energy laser fluences and acetone like the liquid medium. Samples were characterized by UV-Vis, fluorescence, Raman spectroscopy and TEM. Results show that using different energy laser fluences during the ZnO NPs synthesis, their fluorescence emission is not spectrally affected since all the emission spectra are identical. However the emission intensity increases as the energy laser fluence is increased, indicating that only the concentration of ZnO NPs in the solution is affected, but not their size. 256 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-499 ] Crystalline CdO nanoparticles in an amorphous matrix of Cd2V2O7 with Er3+ ions Erika Cervantes Juárez ([email protected]) 5 , José G. Quiñones Galván 4 , Yadira A. González Rivera 5 , Rosendo L. Lozada Morales 5 , Enrique Campos Conzález 1 , Orlando Zelaya Angel 1 , Sergio Jimenez Sandoval 2 , Efrain Rubio Rosas 3 1 CINVESTAV CINVESTAV, Unidad Querétaro 3 CUVyTT 4 Departamento de Física, Centro Universitario de Ciencias Exactas e Ingenierías, Universidad de Guadalajara 5 FCFM-BUAP 2 Er3+ ions have been introduced into a matrix of Cd2V2O7 using a conventional meltquenching method. X-ray diffraction results indicate the presence of approximately 40 nm sized CdO nanocrystals embedded within the amorphous Cd2V2O7 matrix. The presence of such nanocrystals was confirmed by transmission electron microscopy. Raman spectroscopy measurements confirm that the amorphous matrix is composed by Cd2V2O7. The band gap obtained by optical absorption is 2.84 eV. From the photoluminescence spectrum the 4 4 4 electronic transitions observed are the {2H11/2, S3/2, F9/2, I9/2} 4 4 4 3+ → I15/2 and S3/2 → I13/2 corresponding to Er . Thermally activated transport was observed by dark conductivity measurements taken room temperature to 450 K. The morphology and chemical composition of the sample were determined by scanning electron microscopy and energy dispersive spectroscopy respectively. 257 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-507 ] Green synthesis of stable magnetite Fe3O4 nanoparticles in aqueous extract of hydroponic crops Araceli Aldana Vázquez ([email protected]) 2 , Jaime Santoyo Salazar ([email protected]) 1 1 2Departamento de Física, Centro de Investigación y Estudios Avanzados del Instituto Politécnico Nacional, CINVESTAV-IPN, Zacatenco, 07360 México, D.F. 2 Posgrado de Nanociencias y Nanotecnología, Centro de Investigación y Estudios Avanzados del Instituto Politécnico Nacional, CINVESTAV-IPN, Zacatenco, 07360 México, D.F. In this work, we report two biosynthesis of Magnetite (Fe3O4) nanoparticles (~10nm) obtained from dried biomass in aqueous solutions. The green precursors used were extracts of (1) greenhouse hydroponic lettuce (Lactuca sativa: a plant that generates lots of root and Biomass) and (2) Sumac leaves (Rhus typhina). The advantages of these routes are green technology of low cost and reproducible processing. The extracts from these plants have ion precursor high tannin biomolecule, which is the main organic chain to produce the chemical reaction between water and metal ions. The control of particle size of Magnetite (Fe3O4) during the reactions depends from pH and molar concentration in air. Nanoparticles were analysed by Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), X-Ray Electron Diffraction Scattering (EDS) and X-Ray Diffraction (XRD). These results are contribution to consider this synthesis method for future extend of large scale production. Keywords: Bioreduction, Tannin, biomass, nanoparticles. Acknowledgments: Conacyt Ph.D. and CINVESTAV-IPN Fellowships. Conacyt Project (Sa/ZAC/FI/2013/000765), Lotto BioNano Laboratories and CINVESTAVIPN. 258 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-512 ] Study of ablation and thermal damage induced by laser irradiation in nanostructured materials Lis Tamayo-Rivera ([email protected]) 1 , Emma Vianey GarcíaRamírez 2 , Ariadna Sánchez-Castillo 1 , José Alfredo Pescador-Rojas 1 , Jorge Alejandro Reyes-Esqueda 2 1 Escuela Superior de Apan, Universidad Autónoma del Estado de Hidalgo, Apan, Hgo, CP.43920, México 2 Instituto de Física, Universidad Nacional Autónoma de México, Ciudad de México. CP.04510, México Metal nanoparticles embedded in a dielectric matrix have become one of the most interesting systems, due to the presence of so-called Surface Plasmon Resonance. Those materials and its nonlinear optical interactions have been widely studied; however, the origin of the nonlinear response and its dependence with the Surface Plasmon Resonance has not been clearly understood yet. It is well known that, resonant nonlinear response is bigger than nonresonant nonlinear response; however, linear absorption in resonant regime can also be injurious because a large amount of the incident energy is absorbed by the sample to be released thermally by a non-radiative process. The electromagnetic energy absorbed causes an increase in local temperature, and with it, a structural change in the irradiated area. To be able to explain the mechanisms behind the nonlinear response it is necessary to separate the desired phenomena in the nonlinear regime from the possible permanent changes induced in the material. In this paper we show the presence of optical ablation and thermal damage induced by laser irradiation in nanostructured materials. The work aims to identify the observed damage in the sample: deformation, aggregation and ablation of nanostructures; as a function of the local temperature reached, i.e, as a function of the optical energy absorbed by the sample. 259 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-518 ] Thermal Analysis in Air and Nitrogen Atmospheres of Single Wall Carbon Nanotubes by Raman Spectroscopy. Leticia Ithsmel Espinosa Vega ([email protected]) 1 , Ricardo Guirado López 2 , Ángel Gabriel Rodríguez Vázquez 1 1 Coordinación para la Innovación y la Aplicación de la Ciencia y la Tecnología (CIACYT), Universidad Autónoma de San Luis Potosí, Universidad Autónoma de San Luis Potosí, Álvaro Obregón 64, San Luis Potosí, S.L.P., 78000, México 2 Instituto de Física, “Manuel Sandoval Vallarta”, Universidad Autónoma de San Luis Potosí, Álvaro Obregón 64, San Luis Potosí, S.L.P., 78000, México Given the widespread applications of carbon nanotubes it is very important to know their behavior under extreme physical conditions one of them it is the sensitivity of carbon nanotubes, used as NO2 sensors, is found to be largely influenced by oxidative treatment so it is necessary a complete analysis about the comportment that this kind of materials have in different atmospheres to heated. The temperature dependence of the Radial Breathing Mode Raman spectra of Single Wall Carbon Nanotubes (SWCNT) is irreversible under the presence of oxygen, but it is reversible up to 1000 K in nitrogen ambient. We present a combined experimental and theoretical study using Density Functional Theory (DFT) calculations and molecular dynamics simulations, in order to analyze the structural properties and chemical reactivity in the SWCNT. Our results shows that the irreversibility is due to degradation of the SWCNT produced by a dissociative chemical adsorption of oxygen by intrinsic defects on the nanotube surface. Oxygen opens the nanotubes forming semitubes that lead to the different diameter distribution observed by Raman scattering. In the absence of oxygen, the associative chemical adsorption of nitrogen by the intrinsic defects avoids the opening of the nanotubes up to 1000K. Additionally, Raman spectroscopy in back-scattering geometry has been used for the characterization in a complete process were the carbon nanotubes are heating in nitrogen ambient at 1000 K and then in oxygen ambient until the same temperature. We observe than the annealing in nitrogen avoids the damage in the sample heating in oxygen and the Raman spectra remains stable. 260 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-531 ] Low temperature magnetic behavior of CoFe2O4 nanofibers obtained by electrospinning Diana María Carrillo Flores ([email protected]) 2 , José Trinidad Elizalde Galindo 2 , Carlos Ornelas Gutiérrez 1 , José Rurik Farias Mancilla 2 1 Centro de Investigación en Materiales Avanzados, Miguel de Cervantes 120, 31109, Chihuahua, Mexico 2 Department of Physics and Mathematics, Instituto de Ingeniería y Tecnología, Universidad Autónoma de Ciudad Juárez, Av. Del Charro 450 norte, 32310, Ciudad Juárez, Mexico. The synthesis of the CoFe2O4/Fe2O3 nanofibers was carried out by the electro-spinning in order to study the effect of grain size distribution achieved on the magnetic properties when measured at low temperatures. In this work, the precursor solution was compose of 8%Wt of PVP, with molecular weight Mw 1, 300 K, and 7.65 g of Co(NO3)26H2O and Fe(NO3)26H2O in water. The solution was heated at 60 °C with vigorous stirring for 3 h and then delivered into a metallic needle at a constant flow rate of 0.3 ml/h. After collecting the fibers, these were annealed at 750°C by 1 h. The characterization was carried out by X-ray diffraction (DRX), Transmission Electron Microscopy (TEM) and Vibrating Sample Magnetometry (VSM). XRD patterns exposed a CoFe2O4 as the main phase present in the nanofibers with a cell parameter a = 8.3381 Å. Characterization of morphology carried out with TEM revealed a wide distribution of grain sizes, ranging from 40 to 240 nm. Finally, magnetic properties of calcined samples characterized by VSM, shown a strong temperature dependence of hysteresis loops shape, going from single-phase loops for room temperature to wasp-waisted shaped loops for low temperatures. It show up a change in the magnetic interactions as temperature goes down because the grain size distribution of nanoparticles composing the nanofibers and the different magnetic anisotropy of CoFe2O4 and Fe2O3 phases, being these the underlying responsibles of the hysteresis loops shape. 261 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-532 ] Nanostructure and magnetic properties of electropun MnFe2O4 nanofibers Lizeth Vázquez Zubiate 2 , Diana María Carrillo Flores 2 , Pierre Giovanni Mani González 2 , Carlos Ornelas Gutiérrez 1 , José Trinidad Elizalde Galindo ([email protected]) 2 1 2 Centro de Investigación en Materiales Avanzados, Chihuahua, Mexico. Departamento de Física y Matemáticas, Instituto de Ingeniería y Tecnología, Universidad Autónoma de Ciudad Juárez, Chihuahua, Mexico The synthesis of the MnFe2O4 nanofibers was carried out by the electro-spinning in order to study the effect of grain size distribution achieved on the magnetic properties when measured at low temperatures. In this work, the precursor solution was compose of 10%Wt of PVP, with molecular weight Mw 1, 300 K, and 8.7 g of Mn(NO3)26H2O and Fe(NO3)26H2O in water. The solution was vigorously stirred for 2 h and then delivered into a metallic needle at a constant flow rate of 0.5 ml/h. After collecting the fibers, these were calcined at 800°C by 4 h in air atmosphere. The characterization was carried out by X-ray diffraction (DRX), Transmission Electron Microscopy (TEM) and Vibrating Sample Magnetometry (VSM). MnFe2O4 pure phase was found in the nanofibers from XRD patterns. TEM micrographs revealed a fibers diameter around 600 nm and a wide distribution of grain sizes, ranging from 20 to 100 nm. Magnetic properties of calcined samples characterized by VSM were measured at low temperature to determine the magnetic interactions behavior of the fibers. It was found a change in the magnetic interactions as temperature goes down because the magnetocrystalline anisotropy dependence on it by means of delta M curves. 262 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-541 ] Novel solution process for synthesis of CZTS nanoparticles using oleylamine as solvent Arturo Méndez-López ([email protected]) 2 , Arturo Morales-Acevedo 1 , Yuliana de Jesús Acosta-Silva 2 , Mauricio Ortega-López 2 1 Depto. de Física, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Avenue IPN No. 2508, 07360 Mexico City, DF, Mexico 2 Sección de Electrónica del Estado Solido (SEES), Depto. de Ingeniería Eléctrica, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Avenue IPN No. 2508, 07360 Mexico City, DF, Mexico Chalcopyrite, Cu2ZnSnS4 (CZTS), is widely applied in the fabrication of thin-film solar cells, due to its high efficiency and stability. The high costs and complexity of vacuum processes have driven the development of non-vacuum methods, such as solvothermal approaches using organic solvents and metal salts. To overcome the problems of energy waste and carbon residue, this study synthesized ink of CZTS nanoparticles using the hotinjection method at 230 °C . The resulting CZTS particles were characterized by XRD, Raman, SEM, TEM and UV–vis to investigate the crystal structure, composition, morphology, and band gap. This paper demonstrates the considerable potential for the synthesis of nanoscale CZTS particle ink using a low-cost, simple process, applicable for mass production. 263 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ NSN-545 ] Study of the formation of 2DEG in AlGaAs/GaAs n-doped interface J. Antonio Rojas Rosales ([email protected]) 1 , Gelacio Atondo Rubio 1 , Oscar J. Velarde Escobar 1 , Francisco Ramos Brito 1 , Cristo M. Yee Rendón 1 1 Facultad de Ciencias Físico-Matemáticas, Universidad Autónoma de Sinaloa We study the formation of 2DEG in n-AlGaAs/AlGaAs/GaAs structure, as function of the doping and the space layer between the n-doped AlGaAs and the GaAs layer. We realized self-consistent calculations of quantum bound states of the 2DEG. The problem is solved by discretization of the structure and converting the Schrödinger equation into a central difference and the solving the system by using a shooting method. For solving the Poisson equation we used the same discretization than before and solve for a central difference equation and then enforcing the self-consistent scheme to compute the energy for the 2DEG. We compare our results with the modified Fang-Howard approximation. 264 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [NSN-574] TiO2 inverse opals with palladium nanoparticles inclusions as active film in chemical sensors M. P. Sampedro ([email protected])1, B. Zenteno-Mateo2, M. López Fuentes1, Morales Sánchez M. A1, Hernández Santiago A. A.3, Rojas Rodríguez J. F4. 1 Facultad de Ingeniería Química, Benemérita Universidad Autónoma de Puebla. C.P. 72570, Puebla, México. 2 Facultad de Ingeniería BUAP, Bulevar Valsequillo y Circuito CU, Ciudad Universitaria Puebla, Pue. México. 3 Facultad de Ciencias Químicas, Laboratorio de Química Biofísica, Benemérita Universidad Autónoma de Puebla. C.P. 72570, Puebla, México 4 Facultad de Ciencias Físico Matemáticas, Benemérita Universidad Autónoma de Puebla. C.P.72570, Puebla, México. The TiO2 opals were functionalized with palladium nanoparticles and were used in the fabrication of chemical sensors for the detection of hydrogen (H2) and ammonia (NH3) using hydrogen concentrations in the order of parts per million (ppm) at moderate temperatures (200-500°C). The results showed that the inclusion of palladium nanoparticles on the surface of TiO2 opals improves the sensing performance. Particularly the sensor response increased two-fold and the time constants were reduced to seconds, in comparison with the sensor without palladium nanoparticles at the optimal sensor operating temperature. These results show that the TiO2 inverse opals are an excellent option in the development of thirdgeneration gas sensors. 265 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla PHOTOTHERMAL PHENOMENA, PLASMA AND VACUUM (PPPV) Chairman: Citlali Sánchez Aké (CCADET-UNAM) Oral Session INVITED TALK [ PPP-87 ] Photoacoustic Characterization of Green, Red and Dehydrated Capsicum annuum L. variety Pasilla Francisco Hernández-Rosas 1 , Víctor Rodrigo Barrientos-Sotelo 3 , Rogelio Cano-Casas 3 , Alejandro Benitez 3 , Alfredo Cruz-Orea 2 , Juan HernándezRosas 3 1 Colegio de Postgraduados, Campus Córdoba, Km.348 Carretera Federal CórdobaVeracruz, Congregación Manuel León, Amatlán de los Reyes, Ver., 94946, México 2 Departamento de Física, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal 14-740, México D.F. 07360, México 3 Instituto Politécnico Nacional UPIITA, Av. IPN, No. 2580, Col. La Laguna Ticomán, Del. Gustavo A. Madero, México D.F., 07340, México Chili peppers are an important part of the Mexican diet, such that today they are integrated in the cultural traditions inherited from pre-Columbian ancestors. Nevertheless, research on the chili pepper is still needed. In this work, we used photoacoustic spectroscopy (PAS) to specifically characterize Capsicum annuum L. variety pasilla in three different stages: green, red and dried. Measuring their optical properties using the photoacoustic technique we monitored physiological and biochemical changes occurring in the samples during ripening and drying. Several processes, such as water stress, occur during ripening and dehydration to promote the biosynthesis of new compounds, such as various carotenoids, that are clearly visible in the absorption spectra. In order to obtain information about another physical parameters, we have also measured the moisture content of these peppers and the permeability of their cuticles beginning from the unripe stage until ripening and dehydration of the pasilla peppers. Keywords: photoacoustic spectroscopy; water vapor, diffusion coefficient; water stress. *[email protected] 266 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ PPP-107 ] Polycaprolactone thin films synthesized by low pressure plasma polymerization. J. Antonio Lopez Barrera ([email protected]) 1 , Roberto Olayo Valles ([email protected]) 2 , Juan Morales Corona 2 1 Academia de Física, Universidad Autónoma de la Ciudad de México Plantel Cuautepec, Av la Corona # 320, col Loma la Palma 2 Departamento de Física, Universidad Autónoma Metropolitana Unidad Iztapalapa, Av San Rafael Atlixco 186, col Vicentina We demonstrate the plasma polymerization of e-caprolactone (e-CL) at low pressure. Thin films of plasma-polymerized e-CL were deposited on glass slides and KBr pellets in a tubular plasma reactor at 0.6 mbar. All polymerizations were performed for 120 min with a radio frequency of 13.5 MHz and power was varied between 50 and 120 W. The films were characterized by XRD, TGA, DSC, SEM, and Raman and infrared spectroscopy. Additionally, the water contact angle with the film surface was measured. The results show that the plasma-polymerized e-CL films are significantly different chemically and topologically from poly(e-caprolactone) films. The films prepared by plasma polymerization were used as cell culture surfaces for smooth muscle cells. 267 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ PPP-188 ] Pulsed photoacoustic study of Ag and Au nanoparticles obtained by laser ablation in ethanol Enrique Esparza Alegría ([email protected]) 2 , Miguel Angel Valverde Alva 5 , Tupak García Fernández 6 , Citlali Sánchez Aké 1 , Rosalba Castañeda Guzmán 1 , Mayo Villagrán Muniz 1 , José Luis Sánchez Llamazares 4 , Cesar F. Sánchez-Valdés 4 , M.B. De la Mora 1 , Jean Yves Tovar Sánchez 2 , Ciro Eliseo Márquez Herrera 3 1 CCADET, Universidad Nacional Autónoma de México (UNAM), México D.F., C.P. 04510, México. 2 Facultad de Ciencias, Universidad Nacional Autónoma de México (UNAM), México D.F., C.P. 04510, México. 3 Facultad de Química, Universidad Autónoma de México (UNAM), México D.F., C.P. 04510, México. 4 Instituto Potosino de Investigación Científica y Tecnológica A.C., Camino a la Presa San José 2055, Col. Lomas 4ª sección, San Luis Potosí, S.L.P., C.P. 78216, México 5 Posgrado en Ciencia e Ingeniería de Materiales, Universidad Nacional Autónoma de México (UNAM), México D.F., C.P. 04510, México. 6 Universidad Autónoma de la Ciudad de México (UACM), Prolongación San Isidro 151, Col. San Lorenzo Tezonco, México D.F., C.P. 09790, México. Colloidal silver and gold nanoparticles were obtained through laser ablation in ethanol by using a pulsed Nd:YAG laser with 1064 nm of wavelength and nanosecond pulse duration. Different parameters as energy, spot area, number and repetition rate of the laser pulses were varied during the experiments. The size distribution and shape of the nanoparticles were obtained by transmission electron microscopy. The absorption spectra of the colloids showed the respective plasmon absorption peaks. The pulsed photoacoustic (PA) technique was used to study the ablation process and its influence in the synthesized colloids. This technique allowed to determine both the production rate per laser pulse and concentration of the synthesized NPs. The PA analyses showed a significant reduction of the production rate of the NPs during the first hundreds of the laser pulses. The colloids were also analyzed by atomic absorption spectroscopy that allowed to calibrate the results obtained by pulsed PA technique. Keywords: pulsed photoacousticanalysis; laser ablation in liquid; synthesis of silver nanoparticles 268 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ PPP-201 ] Optoacoustic approach for the characterization of ultrasound and optoacoustic phantoms Bartolome Reyes-Ramírez ([email protected]) 1 , Gerardo Gutiérrez-Juárez 1 , Luis Polo-Parada 2 , Crescencio García-Segundo 3 1 Departamento de Ingeniería Física, División de Ciencias e Ingenierías, Universidad de Guanajuato 2 Department of Medical Pharmacology and Physiology, Dalton Cardiovascular Research Center, University of Missouri-Columbia 3 Imagenología Biomédica: Física y Computacional, Centro de Ciencias Aplicada y Desarrollo Tecnológico, Universidad Nacional Autónoma de México In the last decade development of medical ultrasound devices with frequencies higher to 20 MHz propose new challenges. Some of this is the characterization of test phantoms manufactured from tissue-mimicking-material, which are used to calibrate, assess and quantify the performance of ultrasound scanners. To do this characterization, some physical properties have to be measure; among them are sound speed, impedance, absorption and attenuation of the beam through the tissue. In this study, the thermoelastic model of the optoacoustic effect with one degree of freedom in the spatial coordinates for a plane sample was studied in order to assess the ultrasound speed of solid and semisolid samples as potential phantoms. The model proposed considers a sample with thickness , Beer’s law absorption immersed in a no absorbent fluid with different acoustical impedance. It was show that the optoacoustic signal, in the transmission mode of detection, is composed mainly by a pairs of pulses, with time interval between both pulses equal to , here is the sound speed of the sample [1]. In order to use this result as a method to measure the phantom sound speed, we realize a series of experiments with liquids solutions of cupper nitrate. The optoacoustic pressure was generated by nanosecond laser pulses and registered by homemade capacitive sensors with 28 μm thick Polyvinylidene Fluoride films operating in the piezoelectric mode. The thickness of the sample was 12 mm. The sample sound speed was measured with the approach proposed and using another optoacoustic configuration that is independent of model. The values obtained were 1563 m/s and 1560 m/s, respectively. [1] Solution for the photoacoustic wave equation with a single spatial degree of freedom, Beer's law absorption of radiation and mechanical barriers. F. Herrerías-Ascué, A. GonzálezVega, J. Torres-Arenas, and G. Gutiérrez-Juárez. Modern Physics Letters B, 27(18), article number: 1350135 (20 July, 2013). 269 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ PPP-255 ] Influence of film thickness, fluence and number of pulses on the synthesis of Au nanostructures by laser annealing Jimena Martínez de León Mármol ([email protected]) 1 , Citlali Sánchez Aké 1 , Tupak Ernesto García Fernández 2 1 Laboratorio de Fotofísica, Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México, Apartado Postal 70-186, México D.F., C.P. 04510, México 2 Universidad Autónoma de la Ciudad de México (UACM), Prolongación San Isidro 151, San Lorenzo Tezonco, México D.F., C.P. 09790, México In the last few years metallic nanoparticles and nanostructures have attracted significant interest due their multiple applications of their plasmonic properties. Nowadays there are several techniques to fabricate them, although not all of them are easy, unexpensive or sustainable. Laser annealing is a relatively new technique which has the advantages of being accessible, environment friendly, can be used on multiple materials and substrates, and can also be set to obtain patterns or other structures. However, it is still used mostly empirically and the exact phenomenon is still being studied. Many parameters interfere during the physical processes in this technique such as the material to be treated, the substrate, surrounding atmosphere, applied energy, pulse duration, among others. This work exhibits qualitatively the influence of three chosen variables: energy density (fluence) of the irradiating beam, thickness of the original deposited film and number of pulses received during the treatment. Au films of different initial thicknesses have been deposited previously over glass substrates to be laser annealed using a Nd:YAG laser (355nm operated with a repetition rate of 10Hz and 8ns of pulse lenght). Different values of laser fluence have been used. Finally, the treatment under such conditions has been repeated for different number of pulses. The resulting nanostructures have been characterized by SEM and UV-Vis spectrometry. The tendencies obtained in this study will make the further usage of this technique more precise and easier to handle. 270 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ PPP-425 ] Design and characterization of a Chromel-Alumel thermionic converter José Guillermo Pérez Luna ([email protected]) 1 , Steffanie Jiménez Flores ([email protected]) 2 , Antonio Esteban Jiménez Gonzalez 3 , Salvador Alcántara Iniesta 2 1 Facultad de Ciencias de la Electrónica, Benemérita Universidad Autónoma de Puebla, Av. 14 sur y Av. Sn Claudio, Ciudad Universitaria, Puebla Pue., México, CP 72560. 2 Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Av. 14 sur y Av. Sn Claudio, Ciudad Universitaria, Puebla Pue., México, CP 72560. 3 Instituto de Energías Renovables, Universidad Nacional Autónoma de México, Priv. Xochicalco S/N, Temixco Mor, México, CP 62580 The design and characterization of a thermionic converter (TC) made with electrodes of chromel and alumel is presented. These electrodes are cylindrical form and are located over a vertical structure isolated by ceramic elements. A chromel cylinder is used as the anode while an alumel cylinder is used as the cathode. In the internal cavity of the anode is located a tungsten filament heater. The TC includes an aluminum base and a glass dome that maintain vacuum by using an O-ring located between them. A dual valve is connected at the aluminum base for air extraction and nitrogen introduction. A special curve tracer module was designed to measure the small current generated by the TC. A parametric study for different temperatures in the electrodes was made. Parametric curves for vacuum and nitrogen plasma were obtained for their comparison. 271 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ PPP-500 ] In situ photoacustic characterization for porous silicion growing: detection principles Cristian Felipe Ramirez Gutierrez ([email protected]) 1 , Anderzon Felipe Palechor Ocampo 1 , Mario Enrique Rodriguez Garcia ([email protected]) 1 1 Centro de Física Aplicada y Tecnología Avanzada, Universidad Nacional Autónoma de Mexico Campus Juriquilla, Qro., Mexico The electrical and optical properties of porous silicon (PS) had been widely studied in recent years, and it is well know that the porous silicon (PS) properties depend on porosity, and porosity depends on growing parameters choose for the electrochemical process. Usually PS films are characterized after the electrochemical etch using techniques like scanning electron microscopy (SEM), in order to obtain surface and cross-section parameters that allows the determination of thickness and porous size; profilometry had been used to determine interface roughness; and gravimetry to determine the porosity.These techniques are contact, destructive, and are not able to give information at the same time that the etching process is forming of PS. In this work we develop a photoacoustic cell coupled to electrochemical cell for characterize the growing of PS. The detection is based on the changes in the reflectance coefficient. The changes in the reflectance coefficient is a response of the changes in the thickness of PS and the optical properties of the film. It shows the dependence of photoacoustic signal of the wavelength of the laser and current density of the electrochemical etch, and the same time we have been doing a simple description of the differential equation of the heat diffusion with the reflectance corrections to reproduce the photoacoustic signal obtained. 272 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla Sesión Poster [ PPP-30 ] Photoacoustic technique in the study of photosynthesis aquatic lirium (eichhornia crassipes) exposed to ultrasound Jeniffer Calderón ([email protected]) 1 , Alejandro Rojas 2 , Leslie Salazar 2 , Maira Jiménez 2 , Antonio Calderón 1 , Gabriel Peña 3 Instituto Politécnico Nacional, Unidad CICATA Legaria. Instituto Politécnico Nacional, Unidad Profesional Interdisciplinaria de Biotecnología. 3 Universidad Francisco de Paula Santander, UFPS, Colombia. 1 2 Eichhornia Crassipes, water hyacinth, is a free float plant native of the Amazon, Brazil, which by the beauty of its flowers has been propagated to almost all the tropical and sub-tropical regions of the world. This plant is a weed, which causes consequences extremely unfavorable for the environment and for the diverse human activities that are developed in the bodies of water. We report the effect of the intensity of ultrasound (US) in the photosynthetic activity of Aquatic Lirium (Eichhornia Crassipes), specifically the absorption spectrum of the photosynthetic pigments using the photoacoustic technique. For this, we use power densities values of US irradiation of 1 mW/cm2, 8 mW/cm2 and 16 mW/cm2, with a frequency of 17Khz and five hours of exposure time, in all cases. We show the effect of US irradiations to generate cavitation in the watery parts of the Aquatic Lirium or water hyacinth, in order to obtain inhibition of its photosynthetic activity. These results show the utility of the ultrasound irradiation, as well as, the importance the photoacoustic technique in the photosynthesis monitoring in Aquatic Lirium. 273 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ PPP-120 ] Diagnostics of the combination of silicon and bismuth plasmas in a nitrogen atmosphere Enrique Camps ([email protected]) 1 , Johans Restrepo 1 , Johans Restrepo 2 , Stephen Muhl 3 1 Departamento de Física, Instituto Nacional de Investigaciones Nucleares, Apartado Postal 18-1027, México D.F. C.P. 11801, México 2 Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Apartado Postal 70-360, Coyoacán, México, D.F. 04510, México 3 Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Apartado Postal 70-360, Coyoacán, México, D.F. 04510, México. In this work two laser ablation plasmas which expand perpendicularly to each other, in a nitrogen atmosphere, were studied using optical emission spectroscopy and a planar Langmuir probe. The plasmas were formed by the ablation of silicon and bismuth targets. The Langmuir probe was used to measure the mean kinetic ion energy and the plasma density. The optical emission spectroscopy was used to determine the excited chemical species present in the plasmas, as well as their temporal behavior. This study was carried out at pressures between 2 and 40 x 10-3 Torr and laser fluences between 2 and 15 J/cm2. During the ablation of the silicon target in the nitrogen atmosphere we observed species corresponding to single and double charged Si ions, excited neutral silicon and singly ionized molecular nitrogen. For the case of the ablation of the bismuth target the observed species corresponded to excited neutral bismuth. The main emitting species depended on the working pressure and the energy of the ablated ions. During the simultaneous ablation of the two targets, the intensity of the emitting species increased, however the type of species remained the same. The fluence applied to the bismuth target was chosen so that the bismuth ion energy was kept constant at around 50 eV with a plasma density of 5.5 x 10 11 cm-3, and for the case of the silicon target the ion energy was fixed at different levels in order to study the influence of the energy and plasma density on the type of excited species. 274 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ PPP-169 ] Thermal characterization of Castor oil as additive in lubricant oil by photothermal techniques Gemima Lara-Hernández 2 , José de Jesús Agustín Flores-Cuautle ([email protected]) 1 , José de Jesús Agustín Flores-Cuautle 3 , Eder Contreras-Gallegos 4 , Alfredo Cruz-Orea 2 , Juan Carlos BenavidesParra 2 1 Catedras CONACyT, Consejo Nacional de Ciencia y Tecnologia, Av. Insurgentes Sur 1582, Del. Benito Juarez C.P.: 03940, Mexico. 2 Departamento de Física, CINVESTAV-IPN, Av. IPN No. 2508, Col. San Pedro Zacatenco, 07360 Mexico, DF, Mexico. 3 Maestria en Ingeniera Electronica, Division de Estudios de Posgrado e Investigacion, Instituto Tecnologico de Orizaba, Orizaba, Ver. Mexico. 4 Sección de Estudios de Posgrado en Investigación-ESIME-IPN, U.P.A.L.M., Col. San Pedro Zacatenco, 07730 Mexico, DF, Mexico. Over the last years extensively research has been carried out on full or partial substitution of supplies resources coming from renewable resources on traditionally non-renewable, in the case of the automobile sector there are progresses in bio-combustibles (biofuel) [1-3] and synthetic oils coming from vegetable sources [4, 5]. There are strong efforts to find oil additives which can improve oils features in automobile industry, by adding vegetables oils to commercial lubricant oils, is expected to improve oil thermal stability. By using the so-called thermal wave resonator cavity (TWRC) and inverse photopyroelectric technique, different ratios of castor oil (ricinus comunis)-motor oil blends were obtained and their thermal properties were characterized. Several oil-additives concentrations (95%-5%, 90%-10%, 85%-15%, 80%-20%) were measured and thermal diffusivities and effusivities as well as densities are reported, getting full thermal characterization for every concentration. [1] Balafoutis A, Fountas S, Natsis A, Papadakis G. Performance and Emissions of Sunflower, Rapeseed, and Cottonseed Oils as Fuels in an Agricultural Tractor Engine. ISRN Renewable Energy 2011;2011:12. [2] Biodisel. 2015. [3] Vegetable oil as diesel fuel? J Am Oil Chem Soc 1980;57:A805-A19. [4] Campanella A, Rustoy E, Baldessari A, Baltanás MA. Lubricants from chemically modified vegetable oils. Bioresource Technology 2010;101:245-54. [5] Adhvaryu A, Erhan SZ, Perez JM. Tribological studies of thermally and chemically modified vegetable oils for use as environmentally friendly lubricants. Wear 2004;257:359-67. 275 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ PPP-179 ] Thermal and Optical characterization of sunscreen creams by using Photothermal Techniques Elizabeth Díaz Torres ([email protected]) 2 , Margarita Lizeth Alvarado Noguez ([email protected]) 2 , Alfredo Cruz Orea 1 , Feliciano Sanchez Sinencio 1 1 Departamento de Física CINVESTAV-IPN 2 ESFM-IPN The thermal and optical characterization of sunblock oils and creams is important, among other reasons, because they protect the human skin against the UV radiation [1]. In the present study the thermal effusivity and optical absorption spectra of several sunscreen creams were obtained by using two photothermal techniques. The Inverse Photopyroelectric (IPPE) configuration [2] and the Photoacoustic spectroscopy (PAS) [3] techniques were used to obtain the thermal effusivity and optical absorption spectra of the samples respectively. Sunblock creams with different sun protection factors were studied by obtaining their optical absorption coefficient as a function of the incident wavelength. Also these samples were exposed to UV light by several times to monitor their degradation by PAS. References [1] Gabriela Badea, Ioana Lăcătuşu, , Nicoleta Badea, Cristina Ott, Aurelia Meghea, Use of various vegetable oils in designing photoprotective nanostructured formulations for UV protection and antioxidant activity, Industrial Crops and Products 67: 18–24 (2015). [2] A. Mandelis and M. M. Zver “Theory of photopyroelectric spectroscopy of solids” J.Appl. Phys. 57(9) 4421-4430 (1985). [3] C. Hernandez Aguilar, A. Cruz Orea, R. Ivanov, A. Dominguez, A. Carballo, I. Moreno and R. Rico, “The optical absorption Coefficient of Maize Seeds Investigated by Photoacoustic Spectroscopy” Food Biophysics 6:481-486 (2011). 276 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ PPP-233 ] Photoacoustic Characterization of Thin Semiconductor Films Yolanda Elinor Bravo-García ([email protected]) 1 , Patricia Rodríguez-Fragoso 2 , Julio Gregorio Mendoza-Álvarez 2 , Gerardo González de la Cruz 2 1 2 FCE-BUAP Physics Department-CINVESTAV Thermal conductivity, thermal diffusivity and thermal interface conductivity of semiconductor thin film samples on substrate were investigated by means of the photoacoustic technique. The investigated films were grown by liquid phase epitaxy technique. The thermal properties of the samples are identified by comparison with an analytical solution obtained solving the one-dimensional heat conduction across the film and substrate. In particular, the fitting parameter is normalized to one obtained with a reference sample to obtain the thermal conductivity. Furthermore, the determination of the interface thermal conductivity between the film and the substrate gives a qualitative measure of the disorder at the interface. This latter parameter plays an important role on heat transport in layered materials. We estimated the thermal diffusivity, thermal conductivity and the interface thermal conductivity of the ternary InAsSb and quaternary InGaAsSb layers deposited on GaSb (470 mm in thickness) were measured and found to be 0.274 cm2/s, 0.252 W/cm K and 235W/cm2 k for the ternary film and 0.2187cm2/s, 0.287W/cm K and 73.46W/cm2 K for the InGaAsSb film. 277 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ PPP-260 ] Thermal conductivity measurement in concrete with spheres of clay and polystyrene by means of the hot disk technique Jonathan Félix Guarachi Solano 1 , José Antonio Calderón Arenas 1 1 1Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada Unidad Legaria del Instituto Politécnico Nacional, Av. Legaria 694 Col. Irrigación, Del. Miguel Hidalgo, C. P. 11500 México D. F., México. Disc-shaped samples of concrete composite, with diameter of 6.4 cm and thickness of 3.2 mm, were used. Each sample consisted of spheres, of clay and polystyrene, embedded in concrete. In order to ensure the assumptions of an infinite medium and not completely penetrating heat flux through the sample in the axial direction, two of these composite disks were stacked together above the sensor and two more stacked below it, giving us a double thickness of sample. This stacking of disks allowed the generation of more reproducible data. The Hot Disk Thermal Constants Analyzer is an emerging technology that uses the transient plane source technique to measure the in-plane and through-plane thermal conductivity of an anisotropic material in the same test. The sensors used in this test method consisted of a 10µm thick nickel foil embedded between two 25.4 µm thick layers of Kapton polyimide film. The nickel foil was wound in a double spiral pattern and had a radius, R of 6.403 mm. For the more conductive samples the sensor with the larger radius was used. The thermal conductivities were measured at 23oC. Since the test specimens are anisotropic, this test method is suitable for this project. We obtained a reduction of up 50% in the thermal conductivity of the composite samples comparing with samples only of concrete. Keywords: Thermal conductivity, thermal diffusivity, concrete. 278 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ PPP-294 ] Thermal characterization of biodiesel including metallic nanoparticles Genaro López Gamboa 3 , Genaro López Gamboa 4 , José Luis Jiménez Pérez 3 , Zormy Nacary Correa Pacheco 2 , José Francisco SánchezRamírez 1 1 CIBA-Instituto Politécnico Nacional, San Juan Molino Km 1.5 de la Carretera Estatal Sta. Inés Tecuexcomac-Tepetitla, Tlaxcala, 90700 México 2 Instituto Politécnico Nacional-Centro de Desarrollo de Productos Bióticos. Carretera Yautepec–Jojutla, km 6.8, San Isidro, Yautepec, Morelos, México CP 62730 3 UPIITA-Instituto Politécnico Nacional, Av. Instituto Politécnico Nacional 2580. Barrio Laguna Ticomán, 07340. México D.F. 4 Universidad Politécnica del Valle de Toluca (UPVT) km 5.7 Carretera Almoloya de Juárez, Santiaguito Tlalcilalcali, C.P. 50904 Edo. México, México Jatropha biodiesel was prepared using alkaline catalysts. Au nanoparticles with different concentrations were prepared by redox method. The nanoparticles (size φ = 13 nm) were mixed with biodiesel obtaining the bionanofluids with different concentrations. Thermal lens technique was used to characterize the thermal properties of biodiesel containing Au nanoparticles in order to observe how the presence of nanoparticles influences the bionanofluids thermal diffusivity. The characteristic time constant of the transient thermal lens was estimated by fitting the experimental data to the theoretical equations. An increase in the thermal diffusivity for the Au nanoparticles dispersed in biodiesel was observed as concentration of nanoparticles was increased. UV-Vis spectroscopy and TEM were used in order to characterize the bionanofluids. 279 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ PPP-295 ] Photothermal techniques applied for characterization of soybean nanobiodiesel José Luis Jiménez Pérez ([email protected]) 3 , Genaro López Gamboa 3 , Genaro López Gamboa 4 , Zormy Nacary Correa Pacheco 2 , José Francisco Sánchez-Ramírez 1 , Juan Ignacio Escorza Chávez 3 1 CIBA-Instituto Politécnico Nacional, San Juan Molino Km 1.5 de la Carretera Estatal Sta. Inés Tecuexcomac-Tepetitla, Tlaxcala, 90700 México 2 Instituto Politécnico Nacional-Centro de Desarrollo de Productos Bióticos. Carretera Yautepec–Jojutla, km 6.8, San Isidro, Yautepec, Morelos, México CP 62730 3 UPIITA-Instituto Politécnico Nacional, Av. Instituto Politécnico Nacional 2580. Barrio Laguna Ticomán, 07340. México D.F. 4 Universidad Politécnica del Valle de Toluca (UPVT) km 5.7 Carretera Almoloya de Juárez, Santiaguito Tlalcilalcali, C.P. 50904 Edo. México, México Thermal properties of diesel added with nanoparticles could be increased comparing to conventional diesel. This work deals with the enhancement of thermal conductivity of nanofluids from soybean biodiesel added with spherical Ag nanoparticles. Thermal lens spectrometry in the mismatched dual-beam mode was used to measure the thermal diffusivity of the Ag nanoparticles on the biodiesel. The characteristic time constant was estimated by fitting the experimental data to the theoretical expressions. The thermal diffusivity of the biodiesel containing Ag nanoparticles nanofluids was strongly dependent on the presence of the nanoparticles in the range of 0.01 to 0.1 % as concentration of nanoparticles increases. A possible explanation of this phenomena is given. 280 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ PPP-361 ] Photothermal techniques for thermo-optical characterization of mineral transformer oils Andrés Marín Serrano ([email protected]) 2 , Primo Alberto Calva Chavarría 2 , José Abraham Balderas López ([email protected]) 1 1 IPN-UPIBI-Basic Science Department, Av. Acueducto S/N, col. Barrio la Laguna, Ticomán, C. P. 07340, México, D. F., México 2 IPN-UPIITA-Posgraduate studies department, Av. Instituto Politécnico Nacional No. 2580, col. Barrio la Laguna, Ticomán, C. P. 07340, México, D. F., México Photothermal techniques, in the sample´s thickenss scan domain, are presented for thermooptical characterization of mineral oils, used as dielectric fluids for power transformers. Thermal diffusivity and optical absorption coefficient (at 405 nm) were measured for these fluids, by means of a photopyroelectric and photoacoustic techniques, respectively, as a function of the thermal degradation of these substances. Thermal diffusivity values were found very closed to each other, independently of the degree of degradation of the oil, meanwhile, optical absoprtion coeffcient values were found with enough difference as to be considered as physical parameter for the assessment of the thermal degradation of these substances. 281 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ PPP-375 ] Pulsed photoacoustic technique for the characterization of gold nanoparticles formation by thermal annealing thin films Artemisa Mazón Martínez ([email protected]) 2 , Artemisa Mazón Martínez 1 , Citlali Sánchez-Aké ([email protected]) 1 , Tupak Ernesto García Fernández 3 , Mayo Villagrán Muniz 1 1 Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México, P.O. Box 70-186, C.P. 04510, México D.F., México. 2 Facultad de Ciencias, Universidad Nacional Autónoma de México, Cd. Universitaria, C.P. 04510, México D.F., México. 3 Universidad Autónoma de la Ciudad de México (UACM), Prolongación San Isidro 151, San Lorenzo Tezonco, México D.F., C.P. 09790, México. Gold nanoparticles (NPs) were produced by thermal annealing of Au films of different thickness ranging from 20 to 40 nm. In this method, a dielectric substrate coated with a metal thin film is heated up to below the metal fusion point. The NPs formation results from the disaggregation of a film into particles due to the minimization of surface energy when the temperature is increased [1]. The shape, mean size and size distribution of the NPs depend on the film thickness, heating rate and the maximum temperature of the annealing process [2]. In order to study of the evolution of the NPs formation we employed pulsed laser photoacoustic technique, excited by a pulsed Nd:YAG laser. Our study was performed on Au films deposited by sputtering on different dielectric substrates. Since the optical absorption depends on the structure of the irradiated material, this technique may detect the changes produced by the thermal annealing. The results obtained by photoacoustic were compared with the corresponding sample images obtained by scanning electron microscopy. [1] C. Worsch, M. Kracker, W. Wisniewski, C. Rüssel, Thin solid films 520, 4941-4946, 2012. [2] C.V. Thompson, Annu. Rev. Mater. Res., 42, 399-434, 2012. 282 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ PPP-378 ] Photoacoustic Techniques Applied to Thermooptical characterization of Biological Tissues. Melisa Cuevas Sánchez 2 , Lilia Martínez Pérez 2 , José Abraham Balderas López ([email protected]) 1 1 IPN-UPIBI, Av. Acueducto S/N, col. Barrio la Laguna, Ticomán, C. P. 07340, México, D. F., México 2 IPN-UPIITA, Av. Instituto Politécnico Nacional No. 2580, col. Barrio la Laguna, Ticomán, C. P. 07340, México, D. F., México A self-normalized photoacoustic technique, in the modulation frequency domain, suitable for thermo-optical characterization of sample sandwiched between transparent windows, was applied for thermal diffusivity and optical absorption coefficient measurements (at 405 nm and 532 nm) of biological tissues, embedded inside transparent glasses. Biological samples consisted of rat skin tissues with progressive stage of melanoma. Thermal diffusivity values for these samples were found very close to each other, for which this thermal property was shown not quite adequate for health degree of these samples. Optical absorption coefficients values (especially at 405 nm), on the other hand, shown adequate differentiation as to be considered as promises physical parameter for classification of degree of melanoma of these samples. 283 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ PPP-384 ] Relation between gas content and the thermal diffusivity of mineral oils Norma Angélica García Vargas ([email protected]) 2 , Primo Alberto Calva Chavarría 2 , José Abraham Balderas López ([email protected]) 1 1 IPN-UPIBI, Av. Acueducto S/N, col. Barrio la Laguna, Ticomán, C. P. 07340, México, D. F., México 2 IPN-UPIITA, Av. Instituto Politécnico Nacional No. 2580, col. Barrio la Laguna, Ticomán, C. P. 07340, México, D. F., México Results of a research of the relation between the thermal diffusivity coefficient and the degradation level of mineral oils used as dielectrics in power transformers, particularly about its gas content, are reported. To characterize the oil samples, dissolved gases analysis (DGA) and photopyroelectric (PPE) technique were performed in order to obtain the dissolved gas content and the thermal diffusivity coefficient, respectively. The analysis of the relation between these properties showed up that the rise of the thermal diffusivity is attributed to the presence of carbon monoxide and carbon dioxide. In the other hand, the dissolution of acetylene presented a tendency of increasing the thermal diffusivity coefficient while its concentration increased. 284 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ PPP-407 ] Electric field influence on heat transport in aqueous dispersions of carbon nanotubes F. Cervantes-Alvarez ([email protected]) 1 , J.D. Macías 1 , N. Pech-May 1 , J.J. Alvarado-Gil 1 1 Department of Applied Physics, CINVESTAV-Unidad Mérida, Carretera Antigua a Progreso km.6, A.P. 73 Cordemex, C.P.97310, Mérida, Yucatán, México. Carbon nanotubes are among the most interesting materials developed during the last few years due to their outstanding thermal, electrical, and optical properties [1,2]. A good amount of work has also been made in developing diverse composite materials based on carbon nanotubes. In particular, they have attracted special interest for its large aspect ratio in increasing the spatial scale of diverse phenomena. However applications in smart fluids require that the nanotubes, immerse in a fluid matrix, can be manipulated. This can be done using alternating electric fields which favor the formation of carbon nanotubes columnar along the field and avoiding migration of the particles[3]. Those columnar arrangements induce anisotropy which modifies reversibly the mechanical, optical and electrical properties of the composite material. In this work changes on heat transport of aqueous dispersions of multiwall carbon nanotubes, with different concentrations, were characterized using infrared thermography. These changes were investigated as a function of the applied electric field intensity. [1] P.M.Ajayan, O. Stephan, C.Colliex, D.Trauth. Science 265, (1994) [2] S.H. Hsu, M.C. Wu, S. Chen, C.M. Chuang, S.H. Lin, W.F. Su. CARBON 50, (2012) [3] Oliva-Avilés A.I., Avilés F., Sosa V., Oliva A.I., Gamboa F. Nanotechnology 23 (2012). 285 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ PPP-467 ] Temperature dependence of biodiesel thermal diffusivity F. Cervantes-Alvarez ([email protected]) 1 , V.M. Chuc-Palacios 2 , L. Díaz-Ballote 1 , M. Zambrano-Arjona 2 , J.D. Macías 1 , J.J. Alvarado-Gil 1 1 Department of Applied Physics, CINVESTAV-IPN, Carretera Antigua a Progreso km.6, A.P. 73 Cordemex, C.P.97310, Mérida, Yucatán, México 2 Facultad de Ingeniería, Universidad Autónoma de Yucatán, Av. Industrias No Contaminantes por Anillo Periférico Norte S/N, Cordemex, Mérida, Yucatán, México Biodiesel is a renewable fuel option, it is made from vegetable oils or animal fats and it is an alternative to replace fossil fuels. Biodiesel has the advantage of being biodegradable and less pollutant than petroleum diesel but with similar characteristics. In order to know the way in which the biodiesel would work in real conditions, it is of great interest to know its thermal behavior as a function of temperature, in particular in the range around ambient temperatures at which a given machine would start working. Biodiesels studied here were obtained through the transesterification of soybean oil with ethanol, methanol and isopropanol respectively. In this work thermal characterization of biodiesel was performed using the thermal wave resonator cavity (TWRC) technique. Experiments were performed varying the thickness of the cavity and also by performing modulation frequency scans. The behavior of heat transfer was studied in the temperature range from 10 to 70 °C. Changes in temperature were induced by modifying the conventional TWRC coupled with a Peltier cooling-heating cell. Results show that the TWRC provides reliable results even when the biodiesels show higher thermal transport stability. Also we found that the biodiesel thermal diffusivity presents a decrement as the temperature rises. 286 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ PPP-485 ] Influence of heat losses at low frequencies in photothermal experiments. Kelly Martínez González ([email protected]) 1 , Ernesto Marín Moares 1 , Enrique Cedeño Bernal ([email protected]) 1 1 Instituto Politécnico Nacional, Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Unidad Legaria, Legaria 694, Col. Irrigación, C.P. 11500, México D.F., México. In this work experiments based in the photothermal infrared radiometry method and lock in thermography have been designed for thermal diffusivity measurements in solids. Disc shaped samples of different test materials were periodical heated at one of their surfaces at different frequencies using an amplitude modulated laser beam, and the temperature at the rear surfaces was monitored as a function of time using two kinds of infrared detectors: an infrared thermometer and a thermography camera. Then, amplitude graphs as a function of frequency were compared with a theoretical model with and without heat losses by convection and radiation (CRHL) consideration. It has been found that for poor heat conductors at low modulation frequencies the conventional model without CRHL does not fit well the experimental data, while using the proposed model a good agreement was found. From the fits of experimental data to the theoretical model the sample´s thermal diffusivities (wood, plasticine, cork and polypropylene) have been obtained straightforwardly with a good agreement in both experimental detection configurations. This work also demonstrates that in photothermal experiments performed in frequency domain the CRHL must be taken into account at low frequencies for poor heat conductors. 287 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ PPP-498 ] Subsurface microscopy of biased polycrystalline silicon tracks: photothermal and thermo-reflectance images Ernesto Rosales ([email protected]) 1 , A.M. Mansanares ([email protected]) 2 1 Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada del Instituto Politécnico Nacional, Legaría 694. Colonia Irrigación 2 Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas, UNICAMP. Cx. P. 6165, 13083-970 Campinas, SP, Brazil. Thermo-reflectance microscopy has been used the last decade as a suitable for the investigation of micro- and opto-electronic devices in operating cycle. [1] It allows the determination of both heat source distribution and heat propagation properties within specific regions of micrometer devices. The technique is also useful for detecting and imaging defects. Besides the temperature field, it is also sensitive to local electric field, [2] as well as to free-carrier density, which are in their turn disturbed by defects. The noncontact and nondestructive character of the technique is one of its main advantages. It enables aging tests, which are a necessary step in the development of electronic devices, as well as progressive and repetitive treatment such as the application of voltage pulses intended to simulate electrostatic discharge damaging. As a result device scaling in microelectronics, interconnects have to tolerate higher current densities with a greater susceptibility to electromigration failure. Electro-migration is the transport of material resulting the transfer of momentum the current conducting electrons to the metallic ions. The geometry and the microstructure of the conducting connection play an important role in electro-migration and on void formation [3]. High rate of heat generation (Joule dissipation) is associated with the high current density in such interconnects. In addition to Joule dissipation, other heat sources in interconnects originate in thermoelectric effects. Peltier effect was detected at the current modulation frequency f, while Joule effect was measured by analyzing the signal at 2f. The electric current distribution is obtained by using high modulation frequencies to avoid thermal broadening. In this manner, the signal distribution is directly connected to the heat source distribution, which is, in turn, proportional to the square of current density. By lowering the modulation frequency, the heat propagation in the structure is observed in the results. 1. J.A. Batista, A.M. Mansanares, E. C. da Silva, and D. Fournier, J. Appl. Phys. 82, 423 (1997). 2. G. Tessier, G. Jerosolimsky, S. Hole, D. Fournier, and C. Filloy, Rev. Sci. Instrum.. 74, 495 (2003). 3. A. Ghiti and A. G. O’Neill. “The effect of grain boundary diffusion anisotropic on via electromigration failure.” J.Appl. Phys 81 (7), 3064-3068 (1997) 288 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ PPP-503 ] RTA crystallization of unhydrogenated amorphous silicon thin films deposited by rf sputtering system Abraham Pacio ([email protected]) 1 , Hector Juarez 1 , Xavier Mathew 4 , Nicolas Budini 3 , Mauricio Pacio 1 , Cesia Guarneros 2 , Jose Alegandro Garcia 5 1 Centro de Investigación en Dispositivos Semiconductores, Benemérita Universidad Autónoma de Puebla, 14 Sur y Avenida San Claudio, San Manuel C.P. 72570, Puebla, México 2 Instituto Politécnico Nacional, CICATA- Altamira, Km 14.5, Carretera Tampico-Puerto Industrial Altamira, 89600 Altamira, Tamaulipas, MÉXICO 3 Instituto de Física del Litoral (UNL-CONICET), Güemes 3450, S3000GLN Santa Fe, Argentina. 4 Instituto de energías Renovables Universidad Nacional Autónoma de México, Temixco, Morelos 62580, México. 5 Preparatoria "Gral. Lázaro Cárdenas del Río", BUAP, 4 Oriente 412 y 414 Col. Centro, Puebla, México We present results regarding the morphological and electrical characterization of semiconductor junctions formed by deposition of n-type amorphous silicon (a-Si) thin films in a small-scale rf-sputtering pilot system. The amorphous silicon is a material which is deposited by means of RF sputtering technique. This system carried out deposits of thin films inside of an argon atmosphere. The thickness of the film can be controlled varying the deposit pressure, RF power, and target-substratum distances. The amorphous silicon films deposited by means of RF sputtering technique were prepared with the RF power of 40 Watts, the pressure into the camera was modified varying the argon flow to obtain a pressure of 1.2 x 10-2 torr, and varying the deposition temperature of 200 to 600 ° C. We control the thickness of the amorphous silicon films through the deposit pressure and RF power. These parameters control the energy necessary for remove the atoms in the target, and deposit on the substrate surface. The film thickness is 100 to 200 nanometers. The amorphous silicon films were annealing at 900ºC to 1000°C to achieve a complete crystallization by rapid thermal annealing (RTA). This increase the conductivity and the size crystal grain to obtain a high mobility of energy to cross the films. Those parameters make possible application in solar cells. The crystallization evolution was observed in reflectance UV-vis, Raman spectroscopy, optical microscopy and electrical properties. This increase the conductivity and the size crystal grain to obtain a high mobility of energy in the films. Those parameters make possible application in solar cells. The crystallization evolution was observed in reflectance UV-vis, Raman spectroscopy, optical microscopy, X-ray diffraction and electrical characterizations. 289 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ PPP-506 ] Photoacoustic tecnhique, in the modulation frequency domain, for thermo-optical characterization José Balderas López ([email protected]) 1 1 IPN-UPIBI, Av. Acueducto S/N, col. Barrio la Laguna, Ticomán, C. P. 07340, México, D. F., México Photoacoustic technique, in the modulation frequency domain, for thermal and optical characterization of samples is presented. The analytical scheme involves a self normalized procedure which consist in taking the complex ratio of photoacoutic signal in the transmission and front configurations. This procedure was applied to aquous solutions of methylene blue, at different concentrations, for obtaining their optical absorption coefficients (at 660 nm) and black china ink, for obtaining its thermal diffusivity. Excellent agreement with reported values was obtained, showing that the presented self-normalization procedure its adequate for optica absorption measurements for high concentrated samples. 290 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ PPP-527 ] Lock-in CCD Camera Photothermal Beam Deflection Tracking Angel Cifuentes ([email protected]) 1 , Angel Cifuentes 2 , Salvador Alvarado 1 , Humberto Cabrera 3 , Humberto Cabrera 1 , Ernesto Marín 1 1 Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada del Instituto Politécnico Nacional, Legaria 694. Colonia Irrigación, 11500 México D. F. 2 Departamento de Fisica Aplicada I, Escuela Superior de Ingenieros, Universidad del País Vasco, c/ Alameda Urquijo s/n, 48013 Bilbao, España. 3 International Centre for Theoretical Physics (ICTP), Strada Costiera 11, Trieste, Italy and Centro Multidisciplinario de Ciencias, Instituto Venezolano de Investigaciones Científicas, IVIC, Mérida 5101, Venezuela Photothermal beam defection is a well-established technique for measuring thermal diffusivity of certain samples such as thin films and filaments [1]. In this technique, an excitation beam generates temperature variations on the surface of the sample to be studied. These variations transfer heat to the surrounding medium, which may be air or any other fluid. The medium in turn suffers a change in the refraction index, which will be proportional to the temperature field on the sample surface when the distance to this surface is small. The refraction index can be probed by means of a laser beam, which will suffer a deflection, which in turn will be proportional to the induced sample surface temperature variation. If certain experimental conditions are met, a horizontal distance sweep, i.e. parallel to the sample surface, will reveal the thermal diffusivity through simple linear relations [2]. The traditional experiment uses some kind of photo detector, e.g. Quadrant Photo-diode, and some means of amplification, e.g. Lock-in amplifier. Here we present a detection scheme in which a HD CCD camera substitutes all detection hardware utilizing motion detection techniques and software digital signal post-processing. 1. A. Mendioroz, R. Fuente-Dacal, E. Apiñaniz, A. Salazar.ev. Sci. Instrum., 80, 074904 (2009). 2. A. Salazar, A. Sánchez-Lavega. Rev. Sci. Instrum., 65, 2896 (1994). 291 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ PPP-558 ] Monitoring and treatment of 2D and 3D optical images applied to photothermal techniques using a low cost camera and computer software Juan Ignacio Escorza Chávez 2 , José Luis Jiménez Pérez ([email protected]) 2 , Zormy Nacary Correa Pacheco 1 , Jessica Morales Vanegas 3 1 Instituto Politécnico Nacional-Centro de Desarrollo de Productos Bióticos. Carretera Yautepec–Jojutla, km 6.8, San Isidro, Yautepec, Morelos, México CP 62730 2 UPIITA-Instituto Politécnico Nacional, Av. Instituto Politécnico Nacional 2580. Barrio Laguna Ticomán, 07340. México D.F. 3 UPVM, Avenida Mexiquense S/N, Esquina Universidad Politécnica, Col. Villa Esmeralda, Tultitlán, Edo. México, Ticomán, C.P. 54910. In this work, a computer program for the treatment of 2D and 3D images using a low-cost CMOS camera, with the aim of developing an optical instrument for measuring Gaussian laser beam profiles was developed, in order to provide a platform for the geometric parameters associated with it, without the high costs associated with commercial equipment. Once the instrument was designed and built, experimental profiles were obtained by the method of knife edge and compared with those obtained by our image treatment system with the experimental and theoretical 2D resulting good quantitative and qualitative agreement between both methods. In this work, the results were applied for the measurement of laser waist much more quickly and easily when the traditional method was applied. These experiments can be widely used in the thermal lens spectrometry to determine the thermal properties of some fluids. 292 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ PPP-570 ] Thermal effusivity determination in mucinprotein blends by using a photoacoustic configuration Azucena López-López 1 , Emma Gloria Ramos-Ramírez 1 , Margarita Lizbeth Alvarado-Noguez 2 , Alfredo Cruz-Orea 2 , Juan Alfredo SalazarMontoya ([email protected]) 1 1 CINVESTAV-IPN. Department of Biotechnology and Bioengineering 2 CINVESTAV-IPN. Department of Physics Mucins are high molecular weight glycoproteins, heavily glycosylated containing water, salts, and lipids constituting mucous secretions covering surfaces of the digestive, respiratory and reproductive systems in mammals. Interactions of this glycoprotein are of great importance because of the protection functions they play in the gastric system and the recent interest in the study of blends with proteins. Thermal effusivity of materials defines the ability to exchange heat with the environment and is related to other thermo-physical properties such as thermal conductivity, thermal diffusivity, specific heat and density among others. The aim of this study was to determine the thermal effusivity, by using photoacoustic configuration(1), of blends of crude and purified mucins, with soy protein and gelatin, mixed in the ratio 1:1. The obtained results showed values from 1470 to 2670 . The obtained thermal effusivity values in mucins-gelatin blended are closed to the water thermal effusivity value. Reference (1) Balderas-López, J. A., Gutiérrez-Juárez, G., Jaime-Fonseca, M. R. and Sánchez-Sinencio, F. 1999. Measurements of thermal effusivity of liquids using a conventional photoacoustic cell. Review of Scientific Instruments, 70, 2069-2071. 293 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla RENEWABLE ENERGY: SOLAR CELLS AND MATERIALS (RWE) Chairman: Guillermo Santana (IIM-UNAM) Oral Session [ RWE-20 ] New about the solar cells Igor Volovichev 1 , Yuri Gurevich ([email protected]) 2 1 A.Usikov Institute for Radiophysics and Electronics, National Academy of Sciences of Ukraine, 12 Ac. Proscura St., Kharkov 61085, Ukraine 2 Departamento de Fisica, CINVESTAV-I.P.N., 2508, Apartado Postal 14-740, Mexico D.F. 07000, Mexico The interplay between physical reasons of nonequilibrium in a steady state and their influence on the linear transport processes in bipolar semiconductors is under investigation. Particular attention is paid to the influence of the energy nonequilibrium on the generationrecombination processes at various semiconductor parameters. It is shown that in the case of a spatially inhomogeneous, but a single temperature of the charge carriers and phonons, the volume recombination rate of the charge carriers in the steady state is completely determined by the splitting of the quasi-Fermi levels. Particular emphasis has been placed on the manifestation of the energy nonequilibrium in the presence of hot charge carriers in a semiconductor. It is shown that in this case the generationrecombination balance shifts, being completely equivalent to the appearance of an additional external generation of the electron-hole pairs. The two-temperature model (with electron temperature being different from the equal hole and phonon temperature) of the Dember photovoltaic effect is used to illustrate that the electromotive force (emf) may differ significantly from its corresponding values with no hot electrons. This additional contribution to the emf depends on neither the Seebeck coefficient nor the temperature gradient and the electron-hole pair generation rate, being solely determined by the level of the electron subsystem heating. 294 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ RWE-66 ] Autocatalytic silver coatings with protective transparent films for solar concentrators José de Jesús Pérez Bueno ([email protected]) 1 , Monserrat Gutiérrez Muñoz 1 , Yunny Meas Vong 1 , Guy Stremsdoerfer 2 , Monserrat Gutiérrez Muñoz 2 1 Centro de Investigación y Desarrollo Tecnológico en Electroquímica, S.C. Parque Tecnológico Querétaro s/n Sanfandila, Pedro Escobedo, Qro., México. 76703. 2 Laboratory of Tribology and Dynamics of the Systems UMR 5513 Ecole Central de Lyon. 36 Avenue Guy de Collongue B P 163 69131, Ecully Cedex, France. In concentrating solar power (CSP) is important to find coatings with high transmittance values (greater than 90%) to protect the reflective materials. These transparent coatings require to be inexpensive and maintaining their optical properties for extended lifetimes under outdoor environments. In this work; organic, inorganic and hybrid coatings were made on highly reflective silver (about 94%) [1], which was deposited by the Dynamic Chemical Plating technique (DCP) on polymer substrates. The coatings obtained comply with the optical characteristics required and were evaluated over time under UV exposure. Also, in this study it was determined which of the different types of coatings increased durability, efficiency, and had the best features for solar concentrators. Silver deposit obtained by DCP technique show a uniform silver film with an average roughness of 8.69 nm. 295 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla INVITED TALK [ RWE-85 ] Influence of growth conditions in the morphology and luminescence of CdS nanowires Osvaldo de Melo ([email protected]) 5 , Osvaldo de Melo 2 , Patricia G. Zayas-Bazán 5 , Karla Gutiérrez Z-B 5 , Karla Gutiérrez Z-B 2 , Guillermo Santana 3 , Jaime Santoyo-Salazar 1 , Josue Esau Romero-Ibarra 4 , Gerardo Contreras-Puente 2 1 Departamento de Física, Centro de Investigación y Estudios Avanzados del Instituto Politécnico Nacional, CINVESTAV-IPN, A.P. 14-740, México D.F. 07360, México Escuela Superior de Física y Matemáticas, Instituto Politécnico Nacional, Unidad Profesional “ALM”, México D.F. 07738, México 3 Instituto de Investigación en Materiales, Universidad Nacional Autónoma de México, Cd. Universitaria, A.P. 70-360, Coyoacán 04510, México D. F 4 Laboratorio Avanzado de Nanoscopía Electrónica, Centro de Investigación y Estudios Avanzados del IPN, CINVESTAV-IPN, A.P. 14-740, México D.F. 07360, México 5 Physics Faculty, University of Havana, 10400 La Habana, Cuba 2 Preparation of 1D semiconductor nanostructures has been strongly developed in recent years. This is because they boast important applications at the nanoscale comprising sensors,[1],[2] 3rd generation solar cells,[3],[4] photodetectors[5] and lasers.[6] In particular, it is expected that nanowires (NWs) of CdS, an important n-type II-VI semiconductor typically used as window in thin film solar cells[7],[8] would greatly rise the area of the absorber material in these devices. At the same time, reflection losses and photo- excited carrier mean free paths could be reduced with a consequent increase in efficiency. In this work, CdS nanowires (NWs) were prepared by the catalytic method using Au coated GaAs and Si substrates. Scanning and transmission electron microscopy techniques (SEM, TEM) allowed observing the morphology and structure of the nanowires as a function of the growth conditions. It was observed that nanowires grown onto Si substrates present larger diameters and smaller lengths than those growth on GaAs ones. It can be related to the different properties of liquid eutectic in each case and to the transport of the species not only though the liquid drop. The NWs show very brilliant photo-luminescence (PL) even at RT. PL spectra as a function of temperature were analyzed and related with the morphology features. ([1]) U. Yogeswaran; S. M. Chen, Sensors 2008, 8, 290-313. ([2]) F. Patolsky, Ch. Lieber, M. Materials Today, 8, 2005, 20-28. ([3]) E. C. Garnett, M. L. Brongersma, Y. Cui, M. D. McGehee, Annu. Rev. Mater. Res. 2011, 41, 269-295. ([4]) M. Law, L. E. Greene, J. C. Johnson,; R. Saykally, P.Yang, Nature Mater. 2005, 4, 455-459. ([5]) H. Kind,; H. Yan,; B. Messer, M. Law, P. Yang, Adv. Mater. 2002, 14, 158-160. ([6]) M. H. Huang, S. Mao, H. Feick, H. Yan, Y. Wu, H. Kind, E. Weber, R. Russo, P. Yang, Science 292, 8, 2001, 1897-1899. 296 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla ([7]) N. Romeo, A. Bosio, V. Canevari, A. Podestá, Sol. Energy 2004, 77, 795-801 ([8]) M. G. Mahesha, K. V. Bangera, G. K. Shivakumar, Mat. Sci. Semicon. Proc. 2009, 12, 89-93 [ RWE-281 ] Towards a high efficiency silicon solar cells based on low cost c-Si CZ wafers Mario Moreno ([email protected]) 2 , José de Jesús Martínez 2 , Pedro Rosales 2 , Alfonso Torres 2 , Dulce Murias 2 , Roberto Ambrosio 1 , Claudia Reyes-Betanzo 2 , Israel Vivaldo 2 1 Benemérita Universidad Autónoma de Puebla, BUAP, Facultad de Electrónica 2 Instituto Nacional de Astrofísica, Optica y Electrónica, INAOE In this work we present the development of crystalline silicon (c-Si) solar cells with efficiencies up to 13%, fabricated on low cost CZ c-Si wafers. In order to develop a low cost fabrication process we are using as dopant source Spin On Dopant (SOD) for the solar cell emitter formation. The use of SOD simplifies the solar cell fabrication process, avoiding the use of dopant gases sources, which reduces the complexity of the atomic diffusion furnace and also increment the safety of the fabrication process, avoiding the use of toxic gases. The c-Si solar cells were fabricated on 300 μm, boron doped (5-15 Ωcm) low cost Hydroxide (KOH), deionized water and isopropyl alcohol (IPA). The cell emitter was formed by diffusion of phosphorous from a SOD source at 950°C, for 10 minutes (this process was also optimized). A 100 nm thick silicon dioxide (SiO2) film was deposited by CVD at 350 °C and was used as a single layer antireflection coating (SLARC). The formation of the upper contact was made with one photolithography step in order to open windows in the SiO2 film and depositing a 0.5 µm thick aluminum grid. Finally, the bottom contact was formed by 5 µm thick aluminum deposition, followed by a thermal annealing at 500 °C. Measurements of the junction depth and doping profile of the solar cells were made by the electrochemical capacitance-voltage technique, while the solar cells characterization was made under standard terrestrial testing conditions (AM1.5, 100 mW/cm2) using the Newport Oriel Sol 2A solar simulator. The cell efficiency obtained by this process for a solar cell of area of 100 mm2 is of 13%. Although the solar cell efficiency reported in this work is still low in comparison with that of high efficiency solar cells, it is important to stress that the reported device was fabricated using a simple structure (that can be industrially compatible) on a Czochralski (CZ) wafer, which has lower minority carriers bulk life time (about four times) and also is much more un expensive (more than five times) than a Float Zone (FZ) wafer, used for higher efficiency solar cells. Moreover, for increase the efficiency of the solar cells reported in this work, several processes must be improved yet, as the surface passivation in order to increase the open circuit voltage (Voc). And as well, the formation of a suitable Back Surface Field (BSF) in the cell back contact using serigraphy techniques, in order to reduce the series resistance and consequently improve the fill factor. 297 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ RWE-317 ] CHEMISORPTION AND REPULSION ENERGIES OF Mg1-xNixH ALLOYS (0 ≤ x ≤ 0.1) G. Ramírez-Dámaso ([email protected]) 3 , G. Ramírez-Dámaso 4 , I. E. Ramírez-Platón ([email protected]) 3 , F. L. Castillo-Alvarado 2 , E. Rojas-Hernádez 3 , A. Valencia-Islas 3 , F. L. Castillo-Alvarado 1 1 2 Becario COFAA-IPN, EDD-IPN. Escuela Superior de Física y Matemáticas del IPN, Av. Instituto Politécnico Nacional s/n, Unidad Profesional Adolfo López Mateos, Edificio 9, col. Lindavista, Del. Gustavo A. Madero, Distrito Federal, C. P. 07738, México. 3 Escuela Superior de Ingeniería y Arquitectura “Unidad Ticomán” del I. P. N., Av. Ticomán No. 600, Col. San José Ticomán, C. P. 07330, Del. G. A. M., México D. F., México. 4 Tecnológico de Estudios Superiores de Ecatepec, Av. Tecnológico s/n esq. Av. Carlos Hank González, Col. Valle de Anáhuac, C. P. 55210, Ecatepec Edo. de México, México . In this work we use Density Functional Theory (DFT) to calculate geometry optimization of Mg1-xNix, for x = 0, 0.02, 0.04, 0.06, 0.08 and 0.1. Hydrogen molecules on the surface (110) of Mg1-xNix are introduced to obtain the Mg1-xNix-H alloy and calculate their geometry optimization, enthalpy, density of states, energies of chemisorption and energies of repulsion with hydrogen on his surface. Results of most stable x concentration of atoms of nickel for hydrogen storage of these alloys are presented. We used generalized gradient approximations (GGA) in CASTEP module, of the molecular simulation program Materials Studio 6.0, to obtain our results. 298 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ RWE-424 ] Position of the maximum value of the exciton-generation profile within the active layer of organic solar cells. Omar Ramírez Sánches ([email protected]) 1 , Víctor Cabrera Arenas ([email protected]) 1 , Luis Martín Reséndiz Mendoza 1 1 Instituto Politécnico Nacional-UPIITA-SEPI, Avenida IPN 2580, La Laguna Ticomán, Del. Gustavo A. Madero, México, 07340, MX Organic solar cells have demonstrated to be attractive due to their advantages in terms of low cost, easy manufacturing, lightness and compatibility with flexible substrates. In order to improve the efficiency, several optical analysis based on the transfer matrix formalism have been performed to determine optimal light absorption. It has been reported that the absorption efficiency can be enhanced by using an optical spacer which could shift the position of the maximum optical electric field into the photoactive layer. However, these works normally present the influence of that layer on the exciton-generation profile based on many calculations for different thicknesses. In this work, we analyzed the second subsystem of the transfer matrix method and found that a simple cosine function can be used to determine the position of the maximum value of the exciton-generation profile. We also found that the function suffers a displacement from the reflecting electrode given by a phase shift that depends on the complex refraction index and the thickness of the metallic contact, optical spacer and photoactive layer. 299 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla INVITED TALK [ RWE-567 ] Selecting CdS:F or CdS:O for window layer application in CdTe-based solar cells. Juan Luis Peña Chapa ([email protected]) 1 , Eric Noé Hernández Rodríguez 1 , Ricardo Mis Fernández 1 , Víctor Rejón Moo 1 1 Applied Physics Department, CINVESTAV-IPN, Apdo. Postal 73, Mérida, Yucatán, 97310, México In this work CdS:F and CdS:O thin films were studied. Films were prepared by the RFsputtering technique in an atmosphere containing Ar mixed with CHF3 or O2 reactive gases. XPS measurements showed that CdS:F films are composed by CdS and CdF 2 while CdS:O comprises the CdS, CdSO4, CdSO3 and CdO2 compounds. Modulation of optical properties was achieved by changing the reactive gas concentration during deposition. According to the transmittance, bandgap and refractive index values, it was concluded that CdS:O thin films are more suitable for window layer application. This work has been supported by CONACYT-SENER (México) under project CeMIE-Sol 207450/P25. 300 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla Sesión Poster [ RWE-17 ] Alcoholic fermentation kinetics of sugars obtained from Agave tequilana Weber Azul leaves using Klyveromyces marxianus and Saccharomyces cerevisiae for the second generation ethanol. Jorge Carlos Avila Gaxiola ([email protected]) 2 , Maria Elisa Evangelina Avila Gaxiola ([email protected]) 2 , Lorena Amaya Delgado 1 , Javier Placido Arrizon Gaviño 1 , Jesus Cervantes Martinez 1 , Oscar Jesus Velarde Escobar 2 , Francisco Ramos Brito 2 , Gelacio Atondo Rubio 2 , Cristo Manuel Yee Rendon 2 , Maria Elisa Evangelina Avila Gaxiola 3 1 Centro de investigación y Asistencia en Tecnología y Diseño del Estado de Jalisco. Unidad de Biotecnología Industrial. Av. Normalista, Col. Colinas de la Normal, Guadalajara, Jalisco, México 2 Facultad de Ciencias Físico – Matemáticas, Universidad Autónoma de Sinaloa. Av. de las Américas y Blvd. Universitarios, Cd. Universitaria, Culiacán, Sinaloa, México 3 Facultad de Ciencias Químico-Biológicas, Universidad Autónoma de Sinaloa. Av. de las Américas y Blvd. Universitarios, Cd. Universitaria, Culiacán, Sinaloa, México Recent investigations of second generation biofuels focus on developing new alternative energy, but are equally important that it does not threat food supplies. The use of agricultural waste has become an attractive source for biomass that could be converted into new energy sources. The present work proposes the use the waste of the tequila industry specifically the leaves of the Agave tequilana Weber Variety Azul as source for biomass. We have found the best conditions for extraction of sugars, for enzymatic hydrolysis of fructans and for acid-enzymatic hydrolysis of the lignocellulosic material contained in agave leaf for the release of reducing sugars (RS) used in the obtention of ethanol. The substrate used was obtained by mixing all extracts of reducing sugars (34 g/L) generated in previously pretreatment that we have already reported. The objective is to evaluate yield of ethanol, the consumption of the substrate and cell growth using two different yeast: Saccharomyces cerevisiae and Klyveromyces marxianus. The fermentation process (under a pH 4.5, 30 ° C and at 100 rpm) of the agave leaf substrate was conducted in a kinetic with times of 3, 6, 12, 18, 24, 30, 36, and up to 42 hours. Cell growth was determined by cell counting method, the ethanol and sugar content at each time of fermentation was determining using techniques of high resolution liquid chromatography, gas chromatography and Raman spectrometry. The fermentation kinetic study allowed us to determine that best production of ethanol for both yeast was a time of 18 hours. Ethanol production with K. marxianus (11.9 ± 0.2 g/L) was higher compared to S. cerevisiae (10.6 ± 0.3 g/L). During fermentation, the yeasts was able to assimilate the substrate because achieved consume 86% of the initial concentration of RS. The ethanol yield obtained with K. marxianus (0.41 g ethanol / g RS) was better with respect to S. cerevisiae (0.36 g ethanol / g RS) yeast. These results show that the substrate of sugar obtained from the agave leaf is a suitable alternative and promising to produce ethanol using both yeasts studied. 301 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ RWE-52 ] A hydrogen study from films to structures for stable pm-Si:H solar cell devices Leon Hamui ([email protected]) 1,2 , B. Marel Monroy 2 , Jaime Santoyo-Salazar 1 , Guillermo Santana 2 1 Departamento de Física, Centro de Investigación y de Estudios Avanzados, A.P. 14-740, Gustavo A. Madero, México, D.F. 2 Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México. A.P. 70-360, Coyoacán, C.P. 04510, México, D.F. In the last years hydrogenated amorphous silicon (a-Si:H) has been the thin film base material for the manufacturing of large area electronic devices such as solar cells. Various techniques have been used to optimize plasma enhanced processes to manufacture hydrogenated amorphous silicon PIN and NIP devices, but a light-induced degradation referred to as the Staebler–Wronski Effect (SWE) is presented. Thus, Hydrogenated polymorphous silicon (pm-Si:H), which consists of nanocrystals embedded in an amorphous matrix, shows greater stability under illumination, better electronic properties and lower defect density than a-Si:H which is attractive for solar cells applications. However, the hydrogen bonding configuration can be more complex since hydrogen can be found in the amorphous matrix and in the nanocrystalline/amorphous interface. Therefore, pm-Si:H is studied in order to understand the effect of the growth parametres on pm-Si:H films, hydrogen bonding and stability were analyzed in this work. HRTEM images evidence nanocrystals with approximate size of 9 nm. A growth surface reorganization was observed. The optoelectronic properties of the films are directly related to the incorporation of hydrogen and whether it is weakly or tightly bonded. A diminution of the optical gap of the pm-Si:H films in the range from 1.71 to 1.65 eV was observed. Furthermore, PIN and NIP structures were studied trying to determine the effect of light-soaking pre-treatments on the hydrogen effusion mechanisms related to the hydrogen stability and its evolution during exodiffusion. We examined the structural and optical properties of PIN and NIP structures after exodiffusion experiments. Also, an analysis of both structures was done in order to determine which one is less affected by light-soaking. We show that long range motion of hydrogen during light-soaking and annealing causes a hydrogen rearrangement on the film and microstructure changes which result in a shift on the exodiffusion peaks. We determined that for the PIN structure a hydrogen diffusion barrier is generated by light-induced defects, which is expected to cause less degradation of its optoelectronic properties under illumination in solar cell applications. 302 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ RWE-72 ] Optimization geometry and density of states in bulk and surface (110) Mg1-xNix alloys G. Ramírez-Dámaso ([email protected]) 4 , I. E. Ramírez-Platón ([email protected]) 3 , E. Rojas-Hernádez 3 , F. L. Castillo-Alvarado 2 , A. Valencia-Islas 3 , C. E. Hernández-Olguín 3 , G. Ramírez-Dámaso 3 , F. L. Castillo-Alvarado 1 1 2 Becario COFAA-IPN, EDD-IPN. Escuela Superior de Física y Matemáticas del IPN, Av. Instituto Politécnico Nacional s/n, Unidad Profesional Adolfo López Mateos, Edificio 9, col. Lindavista, Del. Gustavo A. Madero, D.F., C. P. 07738, México. 3 Escuela Superior de Ingeniería y Arquitectura “Unidad Ticomán” del I. P. N., Av. Ticomán No. 600, Col. San José Ticomán, C. P. 07330, Del. G. A. M., México D. F., México. 4 Tecnológico de Estudios Superiores de Ecatepec, Av. Tecnológico s/n esq. Av. Carlos Hank González, Col. Valle de Anáhuac, C. P. 55210, Ecatepec Edo. de México, México . ABSTRACT In the past two decades, metal hydride has been studied as an alternative for hydrogen storage in metals. In this work we study Magnesium in alloy with Nickel, selecting concentrations of nickel between 0.0 and 0.08. We use Density Functional Theory to optimize the geometric structure hcp of a crystal of MgNi, to determine the density of states and their total enthalpy. We use CASTEP of the molecular simulation program Material Studio 6.0, to build the crystal structure of the bulk alloy Mg1-xNix (for x=0.02, 0.04, 0.06 and 0.08). Then we cleave bulk Mg1-xNix to build the surface in the direction of the plane (110), and then we introduce hydrogen molecules to interact on that surface. With our program of molecular simulation, we optimize the crystal structure of these surfaces with and without hydrogen. Finally we analyze the results of the geometrical optimization, the density of electronic states (PDOS), as well as the total energies both on the bulk and on the surface (110) with hydrogen. 303 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ RWE-126 ] Kinetic study of fermentable sugars released during the enzymatic hydrolysis of lignocellulosic material present in the leaves of Agave tequilana Weber variety blue as a biomass source for second generation biofuel. Maria Elisa Evangelina Avila Gaxiola ([email protected]) 2 , Jorge Carlos Avila Gaxiola 2 , Lorena Amaya Delgado 1 , Oscar Jesus Velarde Escobar 2 , Francisco Ramos Brito 2 , Gelacio Atondo Rubio 2 , Cristo Manuel Yee Rendón 2 1 Biotecnología Industrial, Centro de Investigación y Asistencia en Tecnología y Diseño del Estado de Jalisco, Av. Normalista, Col. Colinas de la Normal, Guadalajara, Jalisco, México. 2 Facultad de Ciencias Físico-Matemáticas, Universidad Autónoma de Sinaloa, Av. de las Américas y Blvd. Universitarios, Cd. Universitaria, Culiacán, Sinaloa, México. Second generation biofuels are developing as an attractive alternative to fossil fuels with the aggregate value that does not compete with the food chain production Common source for second generation biofuels are the agricultural waste. The present work proposes the use the waste of the tequila industry specifically the leaves of the Agave tequilana Weber variety Blue as a promising source of biomass for biofuel production. Lignocellulosic biomass is inexpensive, renewable and abundant source for ethanol production. In the world many studies are focus in the conversion of lignocellulosic biomass to ethanol, using physical, chemical and/or enzymatic treatment for the production of sugars for subsequent alcoholic fermentation. The objective of this work is to study the kinetics of the release of fermentable sugars during the enzymatic hydrolysis of lignocellulosic biomass agave leaf. The enzymatic hydrolysis were performed using three commercial enzyme Celluclast, Viscozyme and Cellic CTec-2 and was monitored from 6 to 24 hours. The reducing sugar obtained at each time of enzymatic reaction were determined by the method photocolorimetric 3,5-dinitrosalicylic acid (DNS) at 540 nm, techniques of high resolution liquid chromatography and Raman spectrometry. The kinetic study allowed us to determine the best enzyme in for releasing sugars in the lignocellulosic biomass of the agave leaves was Cellic CTec-2. The enzyme Cellic CTec-2 achieving maximum release of reducing sugar (33.5 ± 1.0 g / L) at 18 hours of reaction. The yield of enzymatic hydrolysis was 88%. From the results is conclude that the enzyme is compatible with lignocellulosic biomaterial and that the agave leaf is alternative biomass for the production of second generation ethanol. 304 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ RWE-154 ] Vacuum free deposition of Cu2ZnSnS4 films using nanoparticle based paste and their characterization Antonio Aguilar García ([email protected]) 1 , Enrique Quiroga González 3 , Julio Villanueva-Cab 3 , Nini Rose Mathews 2 , Mou Pal ([email protected]) 3 1 Facultad de Ciencias de la Electrónica, BUAP, Ciudad Universitaria, Puebla, México Instituto de Energías Renovables, Universidad Nacional Autónoma de México, 62580 Temixco, Morelos, México 3 Instituto de Física, BUAP, Av. San Claudio y Blvd. 18 Sur Col. San Manuel, Ciudad Universitaria, C.P. 72570, Puebla, México 2 The Cu2ZnSnS4 (CZTS), a nontoxic and earth abundant chalcogenide semiconductor, has been emerged as an alternative to the conventional absorber layers such as CdTe and CuInGaSe2 (CIGS) in thin film solar cells. In the present work, the CZTS nanoparticles were synthesized by a solvothermal method with and without using polyvinylpyrrolidone as a surfactant. The crystal structure, morphology, chemical composition, and optical band gap of the NPs were evaluated by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy and UV-Vis-near IR spectroscopy. The formation of kesterite phase was confirmed by XRD and Raman results. The band gap of the nanoparticles was determined to be 1.5 eV which is suitable to be used in solar cell applications. A paste of CZTS was made using the NPs and was painted on soda lime glass substrate by doctor blading method. The films were annealed at 500 0C for 1 h in N2/S atmosphere and the structural and optical properties were further characterized to confirm the phase purity of the annealed films. The films were found to be photoconductive. Further detailed electrical characterization is under progress. Acknowledgements: Authors acknowledge Dr. Ricardo Agustín Serrano, Carla de la Cerna Hernández and Eric Reyes Cervantes of CUVyTT (Centro Universitario de Vinculación y Transferencia de Tecnología), BUAP for their assistance in XRD, SEM and EDS measurements. This work was partially supported by the project VIEP, BUAP Grant # VIEP/EXC/2015, Mexico. 305 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ RWE-204 ] Thin films of CdTe nanocrystals grown by chemical synthesis Enrique Campos Gonzalez ([email protected]) 2 , Francisco de Moure Flores 1 , Jaime Santoyo Salazar 2 , Claudia Jaramillo Torres 4 , Lorena Eugenia Ramírez Velázquez 4 , Gerardo Contreras Puente 3 , Orlando Zelaya Angel 2 1 2 Department of Chemistry, Universidad Autónoma de Querétaro, Querétaro, México Department of Physics, Centro de Investigación y de Estudios Avanzados del IPN. P.O. Box 14-740, México 07360 D.F. 3 ESFM, Instituto Politécnico Nacional, México D.F., México. 4 ESIQIE, Instituto Politécnico Nacional, México D.F., México By means a chemical synthesis technique thin films of stoichiometric CdTe nanocrystals were prepared on glass substrates in the range 55 – 70 °C of temperature. The layers grow in the cubic zincblende crystalline phase with no preferred orientation. Firstly, Cd(OH)2 films were deposited on glass substrates, after, these films were immersed in a growing solution prepared by dissolution of Te in hydroxymethane sulfinic acid to obtain CdTe. In scanning electron microscopy images the surface of the layers looks even with a granular aspect which indicates that nanocrystals grow giving place to clusters. The average size of nanocrystals lies in the range 6.0 – 12.0 nm and the thickness of the films is in the interval 50 – 100 nm. Raman spectroscopy reveals the LO phonon mode and the first overtone of the CdTe semiconductor. In general, the analysis of the CdTe films indicates that the material have good structural and optical properties to be used in terrestrial solar cells preparation. 306 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ RWE-239 ] Quantum Dots and Solar Cells Arezbith Camarillo Sifuentes ([email protected]) 1 , David Armando Contreras Solorio ([email protected]) 1 1 Academic Unit of Physics, Autonomous University of Zacatecas, Lomas del Patrocinio, Zacatecas, Zac. 98060 It appeared last year the report promoted by Obama: Climate Change Impacts in the United States. This is a contribution of more than 300 experts and the report points out unequivocally that the the climate is changing due to a global warming more pronounced these last 50 years. This global warming is caused by the human activity, essentially by the use of fossil fuels and the colateral emission of greenhouse gases, mainly carbon dioxide. It is then imperative to increase the use of renewable energies like that of photovoltaic. A limiting factor is that the electricity produced by solar cells is still relatively expensive. It is crucial to improve their efficience, which measures how much of the energy received from the Sun, is transformed to electricity. For semiconductor solar cells the bandgap is very important for their efficiency. The ideal bandgap is around 1.3-1.4 eV. A way very promising to improve the efficiency, is the usage of cells based on quantum dots because their bandgap depends on the size, which can be controlled when they are grown by factors like the temperature, time and composition of the dot. In this work, we describe the use of materials like CdS, CdSe and PbS to produce quantum dots. These quantum dots have the potential to absorb a very wide portion of the solar spectrum, from the infrared to the ultraviolet. 307 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ RWE-240 ] Graphene and Solar Cells Ana Cecilia Flores Ortega ([email protected]) 1 , Agustín Enciso Muñoz 1 , David Armando Contreras Solorio ([email protected]) 1 1 Academic Unit of Physics, Autonomous University of Zacatecas, Lomas del Patrocinio, Zacatecas, Zac. 98060 The World consumption of energy grows at an annual rate of 2 % and 85 % of the consumption comes from fossil fuels which are not renewable and they have adverse effects of global warming. The report Climate Change 2014 of IPCC points out that the global climate is harmfully changing due to the increase of carbon dioxide and other greenhouse gas emissions. Then it is essential to increase the use of renewable energies like that produced by solar cells, which directly transform the energy from the Sun into electricity. For this purpose, it is required to low the price of electricity produced by cells, increasing the efficiency and using cheaper materials. Graphene is a relatively new material, increasingly cheaper and environmentally compatible, with extraordinary properties. In this work, we describe the several uses of graphene for manufacturing solar cells. 308 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ RWE-244 ] Interface study of ITO/ZnO layer and their effect on CdS/CdTe solar cells M Zapata-Torres ([email protected]) 1 , E. Hernandez Roriguez 2 , R. MisFernandez 2 , v. Rejón 2 , E. Valaguez Velazquez 3 , J.L. Fernandez Muñoz 1 , J.L. Peña Chapa 2 1 2 CICATA-IPN, Unidad Legaria, Legaria 694 C.P. 11500 D.F., México Departamento de Física Aplicada, CINVESTAV-IPN, Unidad Mérida, Km. 6 Antigua carretera a progreso, C.P. 97310, Mérida, Yucatan, México 3 UPIITA-IPN, Av. IPN 2580, C.P.07340 Mexido D.F. Thin film CdTe/CdS solar cells are typically on the configuration TCO/CdS/CdTe. The thickness of the CdS film is related to the number of incident photons that reach the CdTe. Therefore the decrease of the thickness of CdS increase the number of incident photons in the CdTe layer. However, as the thickness of CdS layer is decreased, we obtain a formation of localized CdTe/ transparent conductive oxide (TCO) junction, which lead to excessive shunting and therefore lower the solar cell efficiency. Using high resistive transparent (HRT) layer is a feasible method to improve the characteristics of CdTe thin films solar cell. The HRT layers in CdTe solar cells include SnO2, Al2O3, ZnSnO4; and recently ZnO. The ZnO has the direct energy gap structure of 3.37 eV, and It can be prepared using low temperature technology such as RF Sputtering. The ZnO is a promising candidate to be used as HRT layer in CdTe thin film solar cells. It is widely reported that inclusion of so called HRT layer between TCO and CdS acts to enhance efficiency, although there is no consensus on the mechanism by which this occurs. In the present work we growth ZnO layer on ITO coated glass substrate. We studied the effect of the annealing on the ITO diffusion on the ZnO layer. The ITO/ZnO layer will be characterized by XPS, X ray diffraction, UV-Vis spectroscopy. In order to study the effect of ZnO and CdS thickness, we used the AMPS-1D solar cell simulator. This work is supported by SEP-CONACYT (project 153245) and SIP-IPN (Project 20150090) 309 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ RWE-257 ] Optical spectroscopy and morphology of CaF2 and CaF2:Tb thin films obtained by electrodeposition technique Antonio Mendez-Blas ([email protected]) 2 , Ma. Estela Calixto 2 , Elias López-Cruz 2 , Bernabe Mari-Soucase 1 1 IDF-Departament de Física Aplicada, Universitat Politècnica de València, Camí de Vera s/n, 46022 València, Spain 2 Instituto de Física, Benemérita Universidad Autónoma de Puebla, Apdo. Postal J-48, Puebla, Pue. 72570, México Calcium fluoride (CaF2) and calcium fluoride terbium doped (CaF2:Tb) thin films obtained by electrodeposition method were studied in this work. According to the results, XRD studies have shown a structural deformation from cubic to tetragonal unit cell as a function of the doping concentration. The optical absorption showed the typical range of transparency from IR to UV. From photoluminescence (PL) results it is possible to identify the f-f electronic transition of Tb3+. The PL at low temperature allows to establish the quenching concentration when the PL intensity decreases at the highest doping concentration value. However, the results also showed that the transition of Tb3+ does not seem to be affected by the mentioned deformation. So, it is possible to use the CaF2 thin films with a double purpose for solar cell applications, not only as antireflection coating, but also as a host for lanthanide doping for down conversion of light. These properties could be very useful for photovoltaic applications, so that the spectral range of light conversion could be increased to achieve higher conversion efficiency values. Acknowledgements: This work was partially supported by VIEP-BUAP and NanoCIS grant 269279. 310 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ RWE-314 ] Effect of Window Layer Optimization on Electronic Properties of Si:H p-i-n Junction Hiram Enrique Martinez Mateo ([email protected]) 1 , Andrey Kosarev 1 1 Electronic Department, INAOE, Luis Enrique Erro # 1, Santa Maria Tonantzintla, Puebla P-i-n structures with plasma deposited Si:H layers are commonly used in commercial devices including application for photovoltaic (PV) solar cells. They are widely reported in literature but many questions still exist, and data reported by different authors are controversial. In this work we report the study of p-i-n junction with Si:H layers deposited by plasma enhanced chemical vapor deposition (PE CVD) with indium-tin oxide (ITO) and zinc oxide doped by Al (AZO) layers as frontal transparent conductors (TCO) and modification of p+layer. The structures have an area S= 0.154 cm2. The samples were fabricated in cluster tool system with 3 chambers from “MVSyst. Inc.”. Intrinsic Si:H was deposited from 10%SiH4+90%H2 mixture, p+ doped layer Si1-XCX:H(B) from B2H6+CH4+SiH4+H2 mixture [X means the carbon content in gas phase according to XCH4+(1-X)SiH4 formula, where X goes from 0.32 to 0.9] and n+ doped layer from 0.01%PH3+ 9.9%SiH4+ 90.09% H2 mixture. All gases used are semiconductor purity. Deposition temperature was Td= 160° C. Rf discharge is excited at frequency f=13.56 MHz and power W= 3W. . Substrates of “Corning 1737” glass coated by AZO (optical transmission T(550nm)= 88% and sheet resistance Rsheet= 100 Ω/sq.) , and ITO (T(550nm)= 88% and Rsheet=20Ω/sq.) were obtained from “Thin Film Devices Inc.”. Summary of main observations and results: a) Jsc increases with the carbon content in gas phase, the maximum value of 12mA/cm2 is achieve at X=0.8. Further increment of carbon in gas phase increases the parasitic series resistance one order of magnitude and therefore, Jsc decreases; b) p+-window layer thickness between 8nm and 10 nm offers the lower parasitic series resistance. For ITO-p-i-n devices, the lowest series resistance is Rs=1.08x102 Ω; c) spectral response, Rph=100*(EQE3.1eV/EQEmax), for short wavelengths increases from 26% to 42% after carbon content in gas phase optimization of the p+-window layer. Spectral response, Rph, for short wavelengths increases up to 74% when thickness of p+-window layer is optimized in the ITO devices. 311 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ RWE-338 ] Perovskites and Solar Cells Cristina de Lourdes Rodríguez Corvera ([email protected]) 1 , David Armando Contreras Solorio ([email protected]) 1 1 Academic Unit of Physics, Autonomous University of Zacatecas, Lomas del Patrocinio, Zacatecas, Zac. 98060 The reports Climate Change Impacts in the United States (2014), promoted by Obama, and Climate Change 2014 of IPCC point out that the global climate is changing with ominous consequences due to a global warming caused by the human activity. This warming is caused essentially by the use of fossil fuels and the side emission of greenhouse gases, mainly carbon dioxide. Then, it is necessary to increase the use of other forms of energies like that of photovoltaic, which transforms the electromagnetic radiation from the Sun directly to electricity. In order to increase the use of electricity from solar cells, it is essential to make more affordable their production, using cheaper materials and increasing the efficiency, which measures how much of the radiation received by the cell from the Sun, is transformed to electricity. The recent use of perovskites for solar cells is very promising. They are a very good prospect as materials for manufacturing solar cells because these materials are abundant and have low cost. Cells made of perovskites have reached an efficiency of 17 % in laboratory. In this work we make an analysis of different types of perovskites, its applications in solar cells, how a cell made of perovskites works, and some difficulties these kind of cells present. 312 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ RWE-438 ] Optimization of aluminum-doped ZnO thin films for application as TCO in a solar cell. José Amauri Serrano Lázaro ([email protected]) 1 , Betsabee Marel Monroy Peláez ([email protected]) 1 1 Instituto de Investigaciones en Materiales, UNAM, Circuito Exterior s/n, Ciudad Universitaria, Coyoacán, D.F., México TCOs (Transparent Conductive Oxides) are of interest due to the peculiar properties they show: high transparency and high electrical conductivity. ZnO is a TCO used in technology of semiconductors for solar cells and optoelectronic applications. Currently, aluminum-doped ZnO thin films are an important part of thin film solar cells. In this project, aluminum-doped ZnO thin films were obtained by the use of the ultrasonic spray pyrolysis technique. The influence of the concentration of aluminum incorporated on the precursor solution (as a dopant atoms source) was studied. The concentration of aluminum was varied from 1.5 to 6 atomic %. Optical, electronic and growth properties of ZnO thin films were analysed. The main goal was to obtain thin films with the adequate properties of a TCO (transmittance >80% and electrical resistivity <10-3 Ω*cm). Results showed that as the concentration of aluminum is increased, there is a change on the preferential growth of crystals in the thin films, from a (002) orientation to a (101). Regardless of the aluminum content, thin films showed high transparency in the visible range (>80%) and they showed an improvement in their electrical properties such a sheet resistance lower than 200 Ω/□ and resistivity lower than 7x10-2 Ω*cm. Best samples were obtained at a 4.45 atomic % of aluminum showing a transparency of 85%, sheet resistance and resistivity of ≈91 Ω/□ and 4x10-2 Ω*cm, respectively. This shows that the thin films deposited by ultrasonic spray pyrolysis technique are adequate for its use as a transparent electrode in a solar cell. Key words: TCO, semiconductor, cell, transmittance, resistivity, resistance, electrode, ZnO, oxides. Acknowledgements: This project was partially funded by PAPIIT-UNAM projects IN108215 and IN100914, CONACYT, Mexico, under Projects 153948 and 179632, and SENER-CONACYT Project 151076. Thanks are due to C. González, C. Flores, A. Tejeda and J.E. Romero for technical support. The authors are grateful to A. Guillen and J. Santoyo from Physics Department, Cinvestav for EDS measurements. 313 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ RWE-496 ] A comparative study of the optical and electrical properties of solar cells using a SiOx coating obtained by HFCVD Karim Monfil Leyva ([email protected]) 1 , Esteban Ojeda Durán ([email protected]) 1 , Jesús Carrillo López 1 , José Alberto Luna López 1 , Roberto Carlos Ambrosio Lázaro 1 , Ana Luz Muñoz Zurita 2 1 Benemérita Universidad Autónoma de Puebla 2 Universidad Politécnica Metropolitana de Puebla The research on third generation solar cells has been increased due to the increasing price, scarcity and toxicity of other elements. Currently, the silicon off-stoichiometric (SiOx) has showed interesting optical properties for optoelectronic applications and it arises as an important and cheap alternative to play an important role in the down-conversion energy in the future. SiOx can be deposited by several techniques like Si-implantation on SiO2, sputtering, laser ablation and Chemical Vapor Deposition (LPCVD) methods. In particular, SiOx films can be easily obtained by Hot Filament Chemical Vapor Deposition (HFCVD) when high purity hydrogen is used as a reactive. In this work, we report a study of the optical properties of SiOx films obtained by HFCVD and their application as a top coating on silicon solar cells. Hydrogen flow (HF) was varied between 25 and 75 sccm to obtain SiOx films. Step measurements were applied to calculate the thickness of our films. Fourier transform infrared (FTIR) measurements were obtained to confirm a change on films stoichiometry. Absorbance spectra of SRO films showed rocking and bending vibration modes similar to stoichiometric silicon dioxide but an asymmetric stretching mode revealed the non-stoichiometric nature of our semiconductor films. SiOx films also showed a red band from 500 to 900 nm (depending on the HF) and this emission was attributed to defects produced by the transport of the precursors. Solar cells with a SiOx coating were obtained using two different lithography methods for metallic contacts. Currentvoltage measurements were obtained from solar cells to calculate figures of merit. The solar cells with metallic contacts obtained by Al-etch have higher efficiency than those obtained by liftoff. The solar cells with highest efficiency also have the SiOx films with the highest photoluminescence, which it confirms the enhancement on electrical parameters according to the improvement in the UV range. 314 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ RWE-562 ] Analysis of quality of production of biodiesel from crude avocado (Persea americana Mill. Hass, Fuerte and Criollo varieties) oils Luis Alberto Juárez-Morán 2 , Edith Cortés-Rodríguez 1 , Isabel HernándezCastillo 1 , Joel Diaz-Reyes ([email protected]) 1 1 Centro de Investigación en Biotecnología Aplicada, Instituto Politécnico Nacional. Ex– Hacienda de San Juan Molino. Km 1.5 de la Carretera Estatal Santa Inés TecuexcomacTepetitla. Tepetitla, Tlaxcala. 90700. México 2 Facultad de Ciencias Fisicomatématicas, Benemérita Universidad Autónoma de Puebla. Av. San Claudio y 18 Sur. Col. San Manuel, Ciudad Universitaria. Puebla, Puebla. 72570. México. The process of transesterification, also called alcoholysis, is the method most commonly used for the production of biodiesel. Crude oil avocado variety Fuerte was extracted by centrifugation. To the crude avocado oil transesterification was reacted with methanol and two conventional catalyst (KOH and NaOH) for 1 hour at a temperature of 60°C. Room temperature Raman Spectroscopy was used to monitor the process of transesterification. The oil Raman spectrum shows four dominant peaks at 3010, 2926, 2889 and 2856 cm-1 attributed to the symmetric stretch =C-H, to the asymmetric bond C-H, to symmetric –CH3 and symmetrical bond –CH2. In particular, two bands were observed in avocado oil located in 1750 and 878 cm-1 attributed to C=O bond and C-C, respectively, while in the Raman spectra after transesterification process the first band shift to 1742 cm-1 and the second disappears, which confirms the formation of biodiesel. 315 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla SEMICONDUCTORS (SEM) Chairmans: Sergio Jimenez (CINVESTAV-Qro) Salvador Gallardo Hernández (CINVESTAV-DF) Sesión Oral [ SEM-14 ] Nonlinear current-voltage characteristics of a semiconductor barrierless structure Andrey Meriuts 2 , Yuri Gurevich ([email protected]) 1 1 Departamento de Fisica, CINVESTAV-I.P.N., 2508, Apartado Postal 14-740, Mexico D.F. 07000, Mexico 2 Department of Materials for Electronic and Solar Cells, National Technical University ‘Kharkov Polytechnic Institute’, 21 Frunze St., Kharkov 61002, Ukraine A nonlinear model for the electric current in a metal-intrinsic semiconductor-metal structure without potential barriers in contacts is considered using a drift diffusion approach. An analytical solution of the continuity equations and the current-voltage characteristic for various recombination rates in the contacts are obtained. It is shown that the current-voltage characteristics of such a structure exhibit not only linear behavior, corresponding to Ohm’s law, but may also possess properties of current-voltage characteristics of the rectifier diode. It is also possible current-voltage characteristics with saturation in both forward and backward directions. Physical model that explains the obtained results is proposed 316 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-15 ] Thermoelectric cooling in bipolar semiconductor structures Enrique Velázquez-Pérez 1 , Oleg Titov 3 , Yuri Gurevich ([email protected]) 2 1 Departamento F1ısica Aplicada, Universidad de Salamanca, Plaza de la Merced, E37008 Salamanca, Spain 2 Departamento de Fisica, CINVESTAV-I.P.N., 2508, Apartado Postal 14-740, Mexico D.F. 07000, Mexico 3 Instituto Mexicano del Petróleo, Eje Central Lázaro Cárdenas 152, C.P. 07730 México, D.F., México This presentation is devoted to the analysis of thermoelectric cooling phenomena in semiconductors containing potential barriers (p-n-junction). The formulation of an adequate self-consistent theoretical model describing the effect is presented. The role of the recombination rate in lineal approximation of the electric current leads to a new formulation of the set of equations describing the Peltier effect that is discussed in detail. The importance of re-distribution of non-equilibrium charge carriers, which has been ignored in most of the publications on this subject, is also shown. Moreover, it is proved that the conventional theory of thermoelectric cooling, which does not take into account the influence of non-equilibrium charge carriers, is not correct in general. In the present work, it is demonstrated that the Peltier effect strongly depends on the recombination rate. In particular, it is shown that the sign of the Peltier effect changes with the value of the recombination rate. 317 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-16 ] Electrical resistance of a bipolar semiconductor in a linear Ohm law Igor Lashkevych ([email protected]) 2 , Yuri G. Gurevich 1 1 Departamento de Física, CINVESTAV-IPN, Apdo., Postal 14-740, 07000 México, DF, México 2 Instituto Politécnico Nacional, UPIITA, Av. IPN, No. 2580, col. La Laguna Ticomán, del. Gustavo A. Madero, México, D.F., C.P. 07340, México The linear electrical resistance of a nondegenerate bipolar semiconductor, which contacts with the metal from both sides, is investigated in general case, i.e., when the presence of both nonequilibrium charge carriers (electrons and holes) and nonequilibrium temperature are taken into account. It is necessary to emphasize that the concentration and energy nonequilbriums arise automatically, when the electrical current flows even in a linear approximation with respect to perturbation. The expression for the electrical resistance is obtained. This expression depends on electrical conductivities of electrons and holes, the thermal conductivity, the bandgap, the lifetime of charge carriers, the surface recombination rate on the contacts of a semiconductor with a metal. The explanation of this is as follows. When the electrical current flows in a semiconductor, then recombination arises due to the nonequilibrium electrons turn up in a semiconductor near its contacts with a metal [1]. Also, nonradiative recombination causes the heat dissipation [2], in turn provoking of the temperature changes. Therefore, not only nonequilibrium charge carriers, but also nonequilibrium temperature arises in a semiconductor. The nonequilibrium temperature will produce thermo-generation of electron-hole pairs in a semiconductor [3,4], i.e., will change the distribution of nonequilibrium charge carriers (electrons and holes). Also, it will generate thermal electrical currents, in turn changing the value of the electrical conductivity. It is shown that the electrical resistance is equal to the classic result, (l is the semiconductor length, S is the cross-sectional area, ( ) is the electrical conductivity of electrons (holes)), only, if the surface recombination rate on the contacts is sufficiently strong or the lifetime of charge carriers is sufficiently small. The partial cases are considered: the semiconductor with small and large thermal conductivities; the monopolar electron and monopolar hole semiconductors; the strong and weak surface recombination rates; the small and large lifetimes of charge carriers. The concrete expressions for the effective electrical conductivity are obtained in all partial cases. [1]. Yu.G. Gurevich, G.N. Logvinov, G. Espejo, O.Yu. Titov, and A. Meriuts, “The role of nonequilibrium carriers in linear charge transport,” Semiconductors 34, 755–758 (2000). 318 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [2]. Yu.G. Gurevich and I. Lashkevych, “Sources of fluxes of energy, heat, and diffusion heat in a bipolar semiconductor: Influence of nonequilibrium charge carriers,” Int. J. Thermophys. 34, 341–349 (2013). [3]. G. Espejo-Lopez, O.I. Lyubimov, O.Yu. Titov, and Yu.G. Gurevich, “Corriente eléctrica de portadores calientes en semiconductores intrínsecos: desequilibrio en concetración,” Revista Mexicana de Física 50, 620– 624 (2004). [4]. I.N. Volovichev, G.N. Logvinov, O.Yu. Titov, and Yu.G. Gurevich, “Recombination and lifetimes of charge carriers in semiconductors,” J. Appl. Phys. 95, 4494–4496 (2004). INVITED TALK [ SEM-18 ] DEVELOPING AN ELECTRONIC DEVICE IN THE EUROPEAN UNION: n-GaInP/pGaAs(C)/GaAs(Si)/GaAs HBT Jaime Mimila-Arroyo ([email protected]) 1 1 Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Dpto. de Ing. Eléctrica-SEES, Av. Instituto Politécnico Nacional No 2508, México D.F. CP 07360, México The heterojunction bipolar transistor (HBT) n-GaInP/p-GaAs(C)/n-GaAs(Si)/GaAs handles current densities as high as ~120 KA/cm² at high frequencies. However, its current gain might be unstable, presenting the so called “burn-in” effect, making circuit design quite complicated. This behavior, since discovered, was related to the presence of residual hydrogen in the HBT base region although with no prove nor proposals of the physical processes that should produce it. This HBT is manufactured and commercialized by several companies with strong differences on current gain and instability, making some of them loose their share of the market. To improve the device performance to the state of the art the European Union supported a research project involving several industrial partners and university labs. The considered approach included all the technological steps since the epitaxial growth and material characterization of the HBT structure, the associated device technology, high frequency characterization until the assessment of the device performance as part of telecommunication subsystems as Voltage Controlled Oscillators (VCOs) and Low Noise Amplifiers (LNAs) tested in the outer space. In this work it will be presented the general research approach and in some detail the studies that yielded as main results: current gain increase and stabilization. This device now is used in a wide range of applications mainly in telecommunications as cell phones, wide band amplifiers, VCOs, LNAs and power amplifiers. 319 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-19 ] FREE ELECTRON GAS PRIMARY THERMOMETER: THE BIPOLAR JUNCTION TRANSISTOR Jaime Mimila-Arroyo 1 1 Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Dpto. de Ing. Eléctrica-SEES, Av. Instituto Politécnico Nacional No 2508, México D.F. CP 07360, México Since the discovery of the junction diode and the bipolar junction transistor (BJT) their ability to sense temperature was clearly established, becoming the most practical semiconductor based thermometric elements, although with low accuracy, even when calibrated. This property stems from the temperature dependence of their charge transport properties as them depend on their free carrier concentration, mobility and diffusivity, which are temperature dependent as well, but mainly from the free carrier energy distribution. Indeed, in semiconducting materials the energy distribution of the free carriers, is given by the FermiDirac statistics which, for energy levels several kT above the Fermi level (k is Boltzmann´s constant and T the temperature), determines that their occupation probability has an exponential dependence on the energy level and the free carriers gas temperature. As a consequence, in a forward biased PN junction the concentration of free carriers at each side of the junction able to overcome the built-in junction energy barrier, and thus the junction current, depends exponentially on the barrier height, modulated by the bias, and on the carrier gases energy distribution i.e., the gas temperature. Since the proposition of Verster who showed that for the case of the BJT using two collector currents; IC1(VEB1) and IC2(VEB2), and their corresponding emitter-base voltages; VEB1 and VEB2, its temperature could be obtained directly this device has been widely used as an inexpensive thermometer. In this presentation, the physics behind the thermometric properties of the BJT will be widely discussed and it will be demonstrated that under particular bias conditions the collector current of a bipolar junction transistor, indeed, constitutes a probe of the energy distribution of the transistor free charge carrier gases from whose behavior its temperature can be extracted through a rigorous mathematical method. It will be also shown that the extracted temperature is independent of every transistor physical parameters and geometry constituting, thus, a primary thermometer. Finally it will be shown that using commercial silicon transistors at several fix temperature points, the method here described, extracts the temperature with an error of a few milli-Kelvin. This primary thermometer being the smallest and simplest actually available. 320 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-67 ] Calculation of Liquid-Solid Coherent Phase Diagram for InAs-InP System to grow Low-Dimension Structures Ulises Zavala Moran ([email protected]) 1 , Andrei Yu. Gorbatchev 1 , Viatcheslav A. Michournyi 1 , Franscisco De Anda 1 1 Instituto de Investigacion en Comunicacion Optica - Universidad Autonoma de San Luis Potosi, Av Karakorum 1470, Lomas 4a. Secc, 78210 San Luis, S.L.P. Previous studies showed that low-dimensional structures can be grown by Liquid Phase Epitaxy (LPE). Particularly, we have reported about experiments in the InAs-InP [1] system and mentioned that the epitaxial structures grown on InP substrates from pure (In-As) liquid phases contain a certain amount of P. The aim of this project is to present a model to describe the complex process that occurs in the liquid-solid interface (l-s). For this purpose we have calculated a coherent phase diagram of the InAsP liquid phase which is in equilibrium with the epitaxial layers grown on the InP substrate, considering the elastic energy generated by the lattice mismatch between the epitaxial layer and the substrate. The Gibbs energies of the liquid and solid phases were obtained using the CALPHAD [2] method with optimized thermodynamic parameters [3-5]. The elastic energy causes the lattice-latching effect and lowers the liquidus point so that the liquid phase at the interface with the solid is actually overheated when a mismatched layer is growing. According to calculations, in the system In-As-P(l)-InP(s) , for liquid phases with a liquidus temperature of 400 ° C, the maximum overheating reaches 26 ° C. These results suggest that at the InAs(l)-InP(s) interface the growth process is the result of two simultaneous competing processes: dissolution and crystallization. [1] U. Zavala Morán, A. Yu. Gorbatchev, V. A. Michournyi, Analysis of epitaxial layers grown by Liquid Phase Epitaxy in contact of InAs liquid phase with InP substrate. LiSci 2015 Summer School. [2] H.L. Lukas, J. Weiss and E. Th. Henig, Strategies for the calculation of Phase Diagrams, CALPHAD 6(3), 229-251, 1982 [3] Jain-Yun Shen, Christian Chatillon, Ibrahim Ansara, Andy Watson, Bridget Rugg, Tim Chart, Optimization of theThermodynamic and Phase Diagram Data in the Ternary As-GaIn Sysem, CALPHAD 19(2), 215-226, 1995 [4] Ch. Li, J.-B. Li, and W. Zhang, A Thermodynamic Assessment of the Ga-In-P System, Journal of Phase Equilibria 21(4), 357-363, 2000 [5] K. Ishida, H. Tokunaga, H. Ohtani and T. Nishizawa, Data Base for Calculating Phase Diagrams of III-V Alloy Semiconductors, J. of Crystal Growth 98, 140-147, 1989 321 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-109 ] 2-D numerical simulation of a tft with chemically deposited Poly-CdS active layer Laura Adriana Berrout Ramos ([email protected]) 1 , Abimael Jiménez Pérez 1 , Amanda Carrillo-Castillo 1 1 Electrical and Computer Department, Universidad Autónoma de Ciudad Juárez, Ciudad Juárez, Chihuahua 32310, México A two-dimensional numerical simulation is performed using physically based device simulator Atlas/Silvaco to analyze the device behavior of a n-type thin film transistor (TFT) with CdS semiconductor thin film, prepared by a low temperature chemical bath deposition (CBD) method. The CdS films were deposited by immersion of the substrates in a CBD solution prepared from cadmium nitrate (Cd(NO3)2), sodium borohydride (NaBH4)/hydrazine (N2H4), pH 10 ammonia buffer and thiourea (Sc(NH2)2). The total reaction volume was adjusted with water to 62 ml. The temperature of the solution was maintained at 70 oC +/- 1 oC for 12 minutes. Meanwhile, the numerical simulation was based on fabricated long channel TFTs. The total Density of Defect States (DDS) distribution of trapping states g(Et) in the polycrystalline CdS films is considered and it is composed of four bands: two tail bands (a donor-like valence band, gTD(Et) and an acceptor-like conduction band, gTA(Et)), and two deep Gaussian level bands (one acceptor-like, gGA(Et) and the other donor-like, gGD(Et)) by The knowledge of the DDS is helpful for the performance study and optimization of n-type TFT with CdS. First, the CdS film was considered as a homogenous material with an effective density of trapping states to avoid complex mesh definitions of multigrain structures. Then, the DDS behavior was predicted by the Fermi-Dirac occupation function. Finally, the capture and emission processes are predicted by Atlas using the Schockley-Read-Hall (SRH) recombination model. As a result of this study, the electrical characteristics of Cds TFTs were predicted using the embedded density of defects model and the principal parameters, such as threshold voltage, mobility and electric field were analyzed. The electrical performance and optimization of these devices could be related to both acceptor and donorlike states (density of vacancies or defects) in the active layer deposited by CBD. 322 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-111 ] Lattice dynamics studies of NbTe2 crystals Aarón Hernán Barajas Aguilar 1 , Francisco Rodríguez Melgarejo 1 , Martín A. Hernández Landaverde 1 , Gabriel López-Calzada 1 , Chuck Irwin 2 , Sergio J. Jiménez Sandoval ([email protected]) 1 1 Centro de Investigación y de Estudios Avanzados del IPN, Unidad Querétaro 2 Department of Physics, Simon Fraser University Transition Metal Dichalcogenides (TMD) are materials with layered structures which consist of stacks of chalcogenide-transition metal-chalcogenide unit layers bind together by weak van-der-Waals-type forces. These characteristics have made possible to get two-dimensional materials with ease by obtaining single molecular layers, which has triggered intensive research efforts from both theoretical and experimental points of view because of the inherent remarkable 2D phenomena that occur in them and because of their potential applicability. NbTe2 is as TMD with metallic-like properties (in-plane resistivity ~10-4 ohm-cm). The NbTe2 crystals were grown by the vapor transport method by heating the elements in an evacuated quartz ampoule. Raman scattering experiments were performed at room temperature on fresh surfaces right after exfoliating NbTe2 crystals. We report here the Raman spectra of NbTe2 crystals obtained by exciting the samples with the 785, 632.8, 514.5, 488 and 457 nm laser lines. Preliminary theoretical results of the calculated vibrational modes using density functional theory are also provided. [ SEM-149 ] New method to extract the emitter series resistance of a bipolar junction transistor JAIME MIMILA-ARROYO ([email protected]) 1 1 Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Dpto. de Ing. Eléctrica-SEES, Av. Instituto Politécnico Nacional No 2508, México D.F. CP 07360, México. Parasitic series resistances in electronic devices are ubiquitous, unavoidable and highly deleterious. Their presence seriously degrades devices performance mainly limiting the handling of power, decreasing the operating frequency and increasing electrical noise. Measuring the series resistance is a complex task as it depends on the current being handled as well as from the temperature at which the device is operating. Here we present a new method to extract the parasitic series resistance of the emitter of a bipolar junction transistor relying on a particular application of the model of Schockley for 323 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla the transistor charge transport properties and experimental measurement of the collector current under a particular bias condition. From these data the precise transistor temperature can obtained as well as the collector saturation current at that temperature which are used to straightforwardly obtain the emitter parasitic series resistance at any device temperature and handling any current. The method has been applied on several out of the shelf transistors. [ SEM-153 ] Current-voltage-temperature characteristics of flexible Schottky barrier diodes based on ZnO/PEDOT:PSS. Norberto Hernandez-Como ([email protected]) 2 , Francisco Hernandez-Cuevas 2 , Rodolfo Garcia-Lozano 1 , Victor Jiménez-Hernandez 1 , Andres Rodriguez Lopez 1 , Israel Mejia 3 , Miguel Aleman 2 1 Centro Universitario Ecatepec, Universidad Autónoma del Estado de México, Ecatepec, México. 2 Centro de Nanociencias y Micro y Nanotecnologías, Instituto Politécnico Nacional, México 3 Department of Materials Science and Engineering, University of Texas at Dallas, USA. In this work, Schottky barrier diodes (SBDs) based on ZnO/PEDOT:PSS thin films have been fabricated. The fabrication process was first done on glass substrates and then transferred to PET substrates. The SBDs current-voltage characteristics were evaluated under different temperatures for the extraction of the effective barrier height (ΦB) and the Richardson constant (A*). These are fundamental parameters that characterize the thermionic emission process in SBDs. The obtained ΦB turned out to be 0.96 eV and the A* was 0.18 A cm-2 K-2, which was significantly lower than the theoretically expected value of 32 A cm -2 K-2 for n-type ZnO. The difference in A* is related to the formation of a non-ideal Schottky contact between the organic PEDOT:PSS and the ZnO. The study and understanding of the SBDs is important because these types of devices can be used in applications such as: ultraviolet photodiodes, half-wave and full-wave rectifiers, temperature sensors, etc. The usage of PET substrates allows the application of the fabricated SBDs in flexible electronics. 324 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-182 ] Local Atomic Structure of Co Doped ZnS Juan Argel Hoy Benítez ([email protected]) 2 , Francisco Javier Espinosa Faller ([email protected]) 3 , José Mustre de León 2 , Juan Lezama Pacheco 1 1 Earth Sciences, Stanford University, 450 Serra Mall, 94306 Stanford, California, Estados Unidos 2 Física Aplicada, CINVESTAV-Mérida, Antigua carretera a Progreso Km 6, Cordemex, 97310 Mérida, Yucatán, México 3 Unidad Experimental Marista, Universidad Marista de Mérida, Periférico Norte Tablaje Catastral 13941, 97300 Mérida, Yucatán, México The local atomic structure of Cobalt doped Zinc sulfide was studied through Extended X-ray Absorption Fine Structure Spectroscopy (EXAFS). Heavily Co doped ZnS thin film samples were grown over soda lime glass substrate by radio frequency magnetron sputtering at a substrate temperature of 150 °C. Thin film characterization includes X-ray Diffraction, Energy Dispersive X-ray Spectroscopy, and Scanning Electron Microscopy. Results from EXAFS relative to nearest neighbour environment around impurities including distance to nearest neighbors and Debye-Waller factors are reported. INVITED TALK [ SEM-216 ] Hybrid Device Structures based on Combination of Organic-Inorganic Semiconductors Andrey Kosarev ([email protected]) 1 , Svetlana Mansurova 2 , Ismael Cosme 2 1 Electronica, Insituto Nacional de Astrofisica, Optica y Electronica 2 Optica, Insituto Nacional de Astrofisica, Optica y Electronica Last years a strong trend on incorporation of non-crystalline materials in electronics paved the ways for new classes of large area and flexible devices. Among them photovoltaic (PV) solar cells and displays are of principal importance. Discovery in 80-ies possibility of doping of amorphous silicon (a-Si:H) deposited by plasma enhanced chemical vapor deposition (PE CVD) resulted in new products such as flat displays (LC AMD liquid crystal active matrix display) and large area (with one or both dimensions more than 1 m) thin film solar cells produced by revolutionary roll-to-roll technology on flexible substrates (metal, plastic). 325 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla Recent results of research and development (R&D) in organic semiconductors (OSC) and their applications for displays and PV solar cells are very impressive and promising e.g. for flat panel displays (OSC displays show better contrast, more brilliant colors vs LC AMD) and for thin film PV solar cells (8% efficiency was demonstrated in laboratory). PE CVD process for deposition inorganic semiconductors (ISC) and multilayered device structures is low temperature technology (Tdeposition < 200 C) and fully compatible with both standard crystalline silicon technology and OS technology. Both PECVD deposition and OS fabrication can be easily scale-up for industrial fabrication. It should be noted that PECVD semiconductors and OS demonstrate complementary optoelectronic properties. Therefore study of hybrid device structures comprising ISC PECVD materials and OS is of much interest and promise. In this talk we present some overview of principal physical ideas for description of electronic properties for both ISC and OSC materials, fabrication of ISC and OSC materials, effect of deposition conditions on opto-electronic properties, some hybrid device structures and their characteristics in comparison with those reported in literature. For illustrations we shall use data and results obtained in INAOE. [ SEM-252 ] Studiy of a new perovskite as the anode for SOFCs José Juan Alvarado Flores ([email protected]) 1 , Jaime Espino Valencia 1 , Jaime Espino Valencia1 1 Universidad Michoacana de San Nicolás de Hidalgo New types of La0.8Sr0.2Cr0.5Mn0.5O3-δ (LSCM) perovskite composites with the addition of Cu in solid solution, XCu (X = 25, 35 and 45%), were synthesized via the sol-gel method as alternative anodes for intermediate-temperature solid oxide fuel cells (IT-SOFCs) and characterized by several techniques. Phase formation of the LSCM-Cu cermets was confirmed by X-ray diffraction (XRD). Electrical conductivity was obtained from room temperature to 800 °C, indicating the presence of two types of behaviors: semiconductor and metal. When the concentration of Cu was 25 and 35%, the dominant behavior was the semiconductor type. The thermal expansion coefficient (TEC) determined was linearly inversely proportional to the concentration of Cu. The results of electrical conductivity, TEC, and morphological analysis suggested that the anodes with 25 and 35% Cu are most suitable for use in the IT-SOFCs. 326 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-321 ] Synthesis and tribological study of graphene modified with MoS2 as additive in lubricating oils. Jorge Alberto Brandy Garza ([email protected]) 1 , Fabio Chalé Lara 1 , José Dolores Óscar Barceinas Sánchez 2 , Felipe Caballero Briones ([email protected]) 1 1 Instituto Politécnico Nacional, Laboratorio de Materiales Fotovoltaicos, CICATA Altamira, Km 14.5 Carretera Tampico-Puerto Industrial Altamira, 89600 Altamira, México. 2 Instituto Politécnico Nacional, Laboratorio de Tribología, CICATA Querétaro, Cerro Blanco No. 141. Col. Colinas del Cimatario, 76090 Santiago de Querétaro, México. The friction and attrition are the main causes of low efficiency in the machines which constitute approximately 30% energy loss consumed globally. To lessen these effects were been used different types of oil-based lubricants with additives that included molybdenum disulfide (MoS2) and graphite, which improve the lubricating properties of the oils. In this research, graphene oxide (GO) was synthesized with different oxidation degrees using the modified method Hummers. The GO was chemically decorated with molybdenum disulfide using sodium molybdate and thiourea as precursors of molybdenum (Mo) and sulfur (S), respectively. The GO powders prepared were tried using a reducing sugar to compare the structure and the tribological properties of GO, reduced GO and MoS2-GO.For recognize the crystalline structure were realized X-ray diffraction analysis, where was found a signal between 10 and 11° related to the plane (002) of the laminar structure of GO. For studying the molecular structure was used infrared spectroscopy for Fourier transform, where was observed the oxygenated groups that been presented in the GO sheet, also the microstructure was determined by Raman spectroscopy. To study the effect of these materials as additives of lubricating oils, dispersions of them were prepared in a oil-based lubricating and were characterized in a ball on disk tribometer, where the friction coefficient is reduced using the GO/MoS2 as additive compared to the other powders used. The attrition surfaces of the discs used in the tribological tests were studied by scanning electron microscopy for determining the lubricating ability of each formulation over the oils. Projects financed by SIP20140293 and SIP 20144607. 327 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-331 ] Nanoelectrical characterization of ZnO:Al films prepared by spray pyrolysis Javier Armando Baron Miranda ([email protected]) 2 , Jordi Díaz Marcos 3 , Ismael Diez Pérez 1 , Fausto Sanz Carrasco 1 , Samuel San Juan Hernandez 2 , Francisco Javier Espinosa Faller 4 , Fabio Felipe Chale Lara 2 , Felipe Caballero Briones ([email protected]) 2 1 Departamento de Química-Física, Universidad de Barcelona, Diagonal 645, y el Instituto de Bioingeniería de Cataluña, Baldiri Reixac, 15-21, 08028, Barcelona, España 2 Instituto Politécnico Nacional, Laboratorio de Materiales Fotovoltaicos, CICATA Altamira, Km 14.5 Carretera Tampico Puerto Industrial Altamira, 89600 Altamira, México 3 Unidad de Técnicas Nanométricas, Centros Científicos y Tecnológicos Nanodivulga UB, Universitat de Barcelona, Lluís Solé i Sabarís, 08028 Barcelona, España 4 Universidad Marista de Mérida, Periférico Norte Tablaje Catastral, 13941, 97300 Mérida México. In this work, zinc oxide films with different amounts of aluminum in the precursor solution (0, 0.5, 1, 2, 5 and 10 % [Al/Zn]) were prepared by ultrasonic spray pyrolysis onto glass substrates using zinc acetate as zinc precursor and 450 oC of substrate temperature. The films were characterized by X-ray diffraction, optical transmittance, scanning electron microscopy and current sensing atomic force microscopy. X-ray diffraction indicates a mixture between pure ZnO and some (Zn,Al)O phase with no evidence of crystalline Al2O3. The transmittance maximum and band gap increases with the [Al/Zn} ratio. The morphology was studied by SEM evolves from hexagonal flakes to hexagonal micro columns that first appear included between the flakes and thereafter dominate in the images. AFM indicate a grain size reduction from ZnO to ZnOAl up to 1% [Al/Zn] in the precursor solution as well as an increment in the conductivity, followed by a grain size increase as a reduction in the conductivity. CAFM indicates that conduction changes from grain bulk conduction to conduction through the grain boundaries when [Al/Zn] increases from 0.5-1% to 2-10%. Undoped ZnO shows uneven conduction paths, possibly related with the uneven distribution of vacancies. Financed by SIP20151074 and SIP2015599 328 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla INVITED TALK [ SEM-370 ] Radiation Effects on Advanced SOI MOSFETS José Joaquín Alvarado Pulido ([email protected]) 1 , Valeriya Kilchytzka 2 , Blanca Susana Soto Cruz 1 , Antonio Cerdeira Altuzarra 3 , Denis Flandre 2 1 Centro de Investigación en Dispositivos Semiconductores, Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Ciudad Universitaria, Edificio 103-C, Blvd. 14 Sur y Av. San Claudio, Fracc. Jardines de San Manuel. C.P. 72450, Puebla, México. 2 ICTEAM Institute, Université catholique de Louvain, B-1348, Louvain-la-Neuve, Belgium 3 Sección de Electrónica del Estado Sólido, CINVESTAV-IPN, D.F. México This work reviews our previous works on the degradations caused by high-energy neutrons and gamma-rays in advanced MOSFETs. Firstly, we showed that the degradation caused by high-energy neutrons in planar fully depleted (FD) and multiple-gate (MuG) SOI MOSFETs are largely similar to that caused by gamma-rays with similar doses. Secondly, a comparative investigation of high-energy neutrons effects on strained and non-strained devices revealed a clear difference in their response to high- energy neutrons exposure. Finally, based on simulations and modeling of partially-depleted (PD) SOI digital circuits, we demonstrated how radiation-induced oxide charge and interface states build-up can affect well-know tolerance of SOI devices to transient effects. 329 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-381 ] MoS2 thin films deposited by chemical bath deposition on Si and glass substrates.* D.E. Perez-Barragan 2 , A.R. García-Sotelo 1 , E. Campos 1 , O. ZelayaÁngel 1 , M. Melendez-Lira ([email protected]) 1 1 Departamento de Física, CINVESTAV-IPN, , Apdo. Postal 14-740, México, DF 07000, México 2 ESIQIE-IPN Escuela Superior de Ingeniería Química e Industrias Extractivas del Instituto Politécnico Nacional, U.P. Adolfo López Mateos, Col. San Pedro Zacatenco, C.P. 07730 México DF, México Even when the increasing interest in MoS2 is driven by their properties as a 2D material, the deposit of MoS2 films using low cost techniques is interesting and allows to explore the feasibility to find routes to produce low cost materials capable to improve photovoltaic structures, etc. The results of the deposit by chemical bath deposition of MoS2 films employing Si and glass substrates are presented. Two precursor were employed: Ammonium molybdate (NH4)2MoO4 and Ammonium molybdate tetrahydrate (NH4)6Mo7O24 · 4H2O. It was found that the first precursor is adequate to obtain amorphous MoS2 films on glass while the second allows to obtain films on silicon. The samples crystallized after a thermal annealing process carried out at 300 °C. UV-Vis spectroscopy indicated a shift in the absorption edge from the MoS2 bulk value, probably related to the film thickness. Samples were characterized also by XPS, Raman and AFM. The results are discussed in terms of the structural characteristic of the films and the interaction with the substrate. *: Partially funded by CONACyT-Mexico 330 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla Sesión Poster [ SEM-13 ] The influence of the recombination on the energy flux density in semiconductor structures José Luis Salazar Laureles ([email protected]) 2 , Yuri G. Gurevich ([email protected]) 1 1 Departamento de Física, CINVESTAV-IPN, Apdo. Postal 14-740, 07000, Distrito Federal, México. 2 Universidad Autónoma Metropolitana Unidad Lerma, Av. Hidalgo Poniente 46, Col. La Estación, Lerma de Villada, Municipio de Lerma, Estado de México, C.P. 52006 A theoretical study of the influence of the recombination to determine the energy flux density is presented. It was studied a linear approximation when there are different temperatures at the ends of one-dimensional semiconductor structures. The mathematical expressions for the energy flux density in the cases of weak and strong recombination are presented. keywords: Recombination, energy flux, semiconductors. [ SEM-49 ] Effect of thermal annealing on points defects in Al-N co-doped ZnO films studied by Raman spectroscopy Luis Zamora-Peredo ([email protected]) 1 , Antonio Martínez-Juan 1 , Julián Hernández-torres 1 , Leandro García-González 1 1 Centro de Investigación en Micro y Nanotecnología, Universidad Veracruzana, Adolfo Ruiz Cortines 455, C.P. 91000, Veracruz, México In this paper, we present the influence of annealing temperature on the structural properties of Al:N co-doped ZnO films by Raman microscopy. The films were deposited by sputtering technique on silicon substrates, Al-concentration was kept constant and the nitrogen flow was changed to 6, 12 and 15 sccm. An annealing process was performed by baking the sample for 30 minutes at temperatures of 300, 400, 500, 600 and 700 °C. In samples without annealing, Raman spectra show two vibration modes one located at 581 cm-1 associated with 331 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla the E1 mode of ZnO and another at 275 cm-1 which has been related to the incorporation nitrogen and the presence of point defects like Zni. Raman intensities of both modes, I275 and I581, decreases when the nitrogen flow increases from 6 to 12 and 15 sccm. After annealing, in the Raman spectra it was observed that I275 increases with temperature, reaches a maximum around 500 ° C and decreases at higher temperatures. X-ray diffraction measurements after annealing show that the tensile stresses have decreased and thus the crystalline quality has improved. [ SEM-61 ] electronic transmission in a finite superlattice of magnetoelectrostatic barriers on graphene with a Pascal profile in the barriers-width Raúl Alberto Reyes Villagrana ([email protected]) 1 , Jaime Raúl Suárez López 1 , Isaac Rodríguez Vargas 1 , Jesús Madrigal Melchor ([email protected]) 1 1 Unidad Académica de Física, Universidad Autónoma de Zacatecas, Carretera Solidaridad con esquina paseo la Bufa S/N, C.P. 98060, Zacatecas, Zacatecas, México. Exist a broad field of research on fractals in different areas such as biology, chemistry, physics, etc. And, it is in this last where they have been deepened in the study of electronic properties of devices using quasi-regulars systems like Cantor, Fibonacci, Period-doubling and more. This paper presents a study on the transport properties of Dirac electrons through a finite superlattice of magneto-electrostatic barriers on a sheet of graphene. We calculate the electronic transmission probability using the transfer matrix method and the formalism of linear Landauer-Büttiker in a finite superlattice where width of the barriers is modulated by a numerical sequence taken from Pascal’s triangle. This sequence is formed the quantity of odd number in each of the triangle rows and has the pattern 1-2-2-4-2-4-4-8-… The sequence has the property of self-similarity. The transmission spectrum is intermediate between that produced by a periodic superlattice and that produced by a disordered one. The transmission spectra are very sensitive to the different parameters in the structure, such as, ratio barrierwidth (Pascal´s profile), incidence angle, height of electrostatic barrier and magnetostatic field. The conductance spectra show a very interesting structure, and shown oscillations in different energy intervals below and up to the electrostatic barrier height. This oscillations can be explained by the opening and closure subband in the bounding state. By other hand, all subbands are degenerate. 332 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-62 ] Conductance and electronic tranmission in a thyristor based-graphene Raúl Alberto Reyes Villagrana ([email protected]) 1 , Jaime Raúl Suárez López 1 , Isaac Rodríguez Vargas 1 , Jesús Madrigal Melchor ([email protected]) 1 1 Unidad Académica de Física, Universidad Autónoma de Zacatecas, Carretera Solidaridad con esquina paseo la Bufa S/N, C.P. 98060, Zacatecas, Zacatecas, México. The thyristor is a device with a structure of four layers, PNPN, similar to a junction between two transistors, PNP-NPN. This device has different applications, but its main function is to control high power systems. This paper presents a study on the transport properties of Dirac electrons through a structure of four magneto-electrostatic barriers on a sheet of graphene, is presented a based-graphene thyristor. The pnpn structure was calculated using the transfer matrix method and the formalism of linear Landauer-Büttiker. We performed a study of four cases. The positive polarization voltage and the magnetic fields were kept constant. The results show that at normal incidence, appears three transmission bands well-defined, with increasing the negative polarization voltage, increases the width of the transmission bands. For oblique incidence, the transmission bands has a toward blue shift and these become narrow. The value of the control voltage (Vn) opens the transmission windows as a function of the deepness of wells. The contour plots have a very interesting structure when the control voltage for the well is more negative. The conductance shows oscillations and peaks in the structure. The conductance oscillations can be explained by the opening and closure of subbands of bounding states. The bond states show degeneration and have three subbands, and goes down with the diminishing of the value of voltage control. Exist interest from the authors to explore further the benefits presented graphene in the development of new devices. 333 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-65 ] Effect of a CdS interlayer in thermochromism and photochromism of MoO3 thin films Marcelino Becerril ([email protected]) 2 , Héctor Silva ([email protected]) 2 , Orlando Zelaya 2 , Rafael Ramírez 1 1 2 Centro de Investigación y de Estudios Avanzados del IPN, Unidad Querétaro, Departamento de Física, Centro de Investigación y de Estudios Avanzados del IPN, Thin films of molybdenum trioxide (MoO3) and the double layer CdS/MoO3 systems were deposited by sequential r.f sputtering of cadmium sulfide (CdS) and MoO3 films on wellcleaned Corning glass substrates. The targets were made from powder of CdS and MoO3. The glass/MoO3 and glass/CdS/MoO3 films were illuminated with light from a 100 W tungsten lamp at times of 45-180 min in order to study the photochromic sensitivity of the films. The films were also thermal annealed at temperatures ranging from 100 to 225 °C to study the thermochromic properties. The X-ray diffraction studies show that the CdS films were polycrystalline and the oxide films were amorphous. Optical absorption shows the presence of an absorption band centered around 850 nm. Photochromic and thermochromic results are in the process. 334 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-96 ] Inelastic light scattering in NbS2 and WTe2 transition metal dichalcogenides Francisco Rodríguez Melgarejo 1 , Aarón Hernán Barajas Aguilar 1 , Martín Adelaido Hernández Landaverde 1 , Gabriel López-Calzada 1 , Chuck Irwin 2 , Sergio Joaquín Jiménez Sandoval ([email protected]) 1 1 Centro de Investigación y de Estudios Avanzados del IPN, Unidad Querétaro 2 Department of Physics, Simon Fraser University Transition Metal Dichalcogenides (TMD) are materials with layered structures which consist of stacks of chalcogenide-transition metal-chalcogenide unit layers bind together by weak van-der-Waals-type forces. These characteristics have made possible to get two-dimensional materials with ease by obtaining single molecular layers. Among these, MoS2 and WS2 have been recently the focus of intensive research efforts from both theoretical and experimental points of view because of the inherent 2D phenomena that occur in them and because of their potential applicability. In this work we present a Raman spectroscopy study of crystalline samples of the two TMD´s. niobium sulfide (NbS2) and tungsten ditelluride (WTe2). The samples were grown by vapour transport by heating the elements in an evacuated quartz ampoule. The Raman scattering experiments were performed at room temperature on fresh surfaces right after exfoliating as-grown crystallites. We report here the Raman spectra of NbS2 and WTe2 obtained by exciting the samples with 785.0, 632.8, 514.5 and 488.0 nm laser lines. The Raman bands are discussed in terms of the known lattice vibrational information and of the applicable group theory. 335 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-98 ] Nanoelectric and photovoltaic caracterization of CuInSe2 films doped with active metals L.E. Arvizu-Rodríguez ([email protected]) 4 , A. Barón-Miranda 6 , F. Caballero-Briones ([email protected]) 6 , S. JiménezSandoval 2 , I. Diez-Pérez 3 , L. Aguilera-Vázquez 4 , U. Páramo-García 4 , F. Sanz 5 , F. Sanz 1 , F. Sanz 3 , F. Chalé-Lara 6 1 CIBER-BBN, Campus Río Ebro Edificio I+D, Bloque 5, 1a planta, C/Poeta Mariano Esquillor s/n, 50018 Spain . 2 CINVESTAV-IPN Unidad Querétaro, Libramiento Norponiente, Fracc. Real de Juriquilla, Juriquilla, México. 3 Departament de Química Física, Universitat de Barcelona, Martí i Franquès 1, 08028, Barcelona, Spain. 4 División de Estudios de Posgrado e Investigación, Instituto Tecnológico de Cd. Madero, Tamaulipas, Mexico. 5 Institute for Bioengineering of Catalonia (IBEC), Edifici Hèlix, Baldiri i Reixac 15-21, 08028 Barcelona, Spain. 6 Instituto Politécnico Nacional, Laboratorio de Materiales Fotovoltaicos, CICATA Altamira. Km 14.5 Carretera Tampico-Puerto Industrial Altamira. 89600 Altamira, México. Investigation has been made as to the incorporation of electrically beneficial for CuInSe 2 impurities, such as with sodium doping. It has been found that the grain boundaries of the CIS not create deep levels and therefore are neutral. However, they have not tested other active dopants that could improve the performance observed with sodium. In this work they were electrodeposited CuInSe2 the films on copper substrates using a bathroom with Cu ratios: Se: In 1: 1: 2. To increase crystallinity and reducer the presence of phases undesirable as Cu-Se or Se films electrochemical post-treatment were carried to the films applying a negative potential in the presence of Se4+ and subsequently a potential positive in the same solution[1]. The films were doped with four electrochemically active metals at three different levels of doping, applying an additional negative potential during deposition. The films were characterized by Raman spectroscopy, atomic force microscopy with current measurement (CAFM), IV macro with light without light and photoelectrochemical current. IV curves and electrical CAFM images by finding an improved rectifying behavior of current with decreasing charge density of the dopant and local variations in conductivity of the materials are compared. The effect of doping on the microstructure and photocurrent measurements and electrochemical photocurrent described. [1] F. Caballero-Briones, L.E. Arvizu-Rodríguez, A. Palacios-Padrós, S. Jiménez-Sandoval, F. ChaléLara, J.L. Fernández-Muñoz, I. Díez-Pérez, F. Sanz, F.J Espinosa-Faller, Phase and surface modification by electrochemical post deposition treatments in ultrasonic-assisted CuInSe2/Cu electrodeposited films properties. Sent: Chalcogenide Letters. 336 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-99 ] Semiconductor thin films of cds as obtained by rf sputtering technique in areas 100 CM2 and its applications in prototype of CdTe pv modules Erendira Velázquez López 2 , Francisco Cortés Carreón 2 , Lourdes Albor Aguilera 1 , Jorge Sastre Hernández 1 , José Alfredo del Oso Acevedo 2 , Rogelio Mendoza Pérez ([email protected]) 2 , Gerardo Contreras Puente 1 1 ESFM-IPN 2 UACM This paper presents the results of processing thin films of cadmium sulfide (CdS) by the use of the technique of Radio-Frequency (RF) sputtering. This semiconductor is the window material employed in the Cadmium telluride (CdTe) PV-modules in areas of 100 cm2. The respective heat treatments with cadmium chloride (CdCl2-TT) and CdTe were performed by the (Close Spaced Sublimation (CSS) technique; while the metal contacts of coppermolybdenum (Cu-Mo) on CdTe were deposited by Sputtering-DC technique. The CdS samples were made with different deposition parameters: substrate temperature, chamber Arpressure, RF-power and CdS thickness. The influence of the deposition parameters are shown in the photovoltaic response of the samples. The results show that the RF-power, and the pressure influence the deposition rate, the layer thickness of the material and therefore in PVperformance with photovoltaic efficiency close to 1%. KEYWORDS: photovoltaic response, CdS, major area. * This work was partially supported by FOMIX 2012-2 CONACYT-GDF under project 189282. 337 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-100 ] Sturm-Liouville formalism in gapless bilayer graphene superlattices: Transmission and transport properties. José Alberto Briones Torres ([email protected]) 2 , René Pernas Salomón 1 , Rolando Pérez Álvarez 1 , Isaac Rodríguez Vargas 2 1 Facultad de Ciencias, Universidad Autónoma del Estado de Morelos, Avenida Universidad 1001, 62209, Cuernavaca, Morelos, México. 2 Unidad Académica de Física, Universidad Autónoma de Zacatecas, Calzada Solidaridad, Esquina Con Paseo La Bufa S/N, 98060, Zacatecas, Zacatecas, México. We study the transmission and transport properties in gapless bilayer graphene superlattices. The Sturm-Liouville formalism and the transfer matrix approach are implemented to obtain the transmission probability, and the Landauer-Büttiker formula to compute the linearregime conductance. In particular, we carry out a comparison between the two methods, and we find that the Sturm-Liouville formalism eliminates the numerical instability present in transfer matrix method for gapless bilayer graphene structures. [ SEM-106 ] Determination of band gap in TiO2 nanotubes using three different techniques Ildefonso Zamudio-Torres ([email protected]) 1 , José de Jesús PérezBueno 1 , Yuny Meas-Vong 1 , Luis Lartundo-Rojas 2 1 Centro de Investigación y Desarrollo Tecnológico en Electroquímica, S.C., Parque Tecnológico Querétaro-Sanfandila, Sanfandila, Pedro Escobedo, Querétaro, México. CP 76703. 2 Instituto Politécnico Nacional, Centro de Nanociencias y Micro y Nanotecnologías, UPALM, Zacatenco México-D.F. 07738, México. In this research, band gap in TiO2 nanotubes (TiO2 NTs) prepared by mean of anodization in an organic medium is studied by three different techniques. TiO2 NTs amorphous were obtaining by mean of anodization, in a bath that containing: 98 % V/V, ethylene glyclol, 2 % V/V water, and 0.3 % weight NH4F, the voltage applied was 60 V during 2 hours. These nanostructures have an internal diameter of 90-120 nm and a wall size of 15-20 nm, the nanostructures showed no crystallographic order, after that the NTs were submitted in heat treatment (480 °C) an then, by mean of X-ray diffraction was possible to establish that anatase structure was reached. Raman technique was used to confirm the vibrational modes 338 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla of anatase phase. Band gap determination was made by mean of three different techniques: Via UV- Vis spectroscopy from the plot of (αhν)n (where n = 1/2, 3/2, 2, and 3 are for direct allowed, direct forbidden, indirect allowed and indirect forbidden transition respectively) versus hν, then extrapolated the straight portion on hν axis at α = 0; the values obtained with photoluminescence and XPS are compared. [ SEM-121 ] GaAs/InGaNAs gaussian superlattice solar cells Carlos I. Cabrera ([email protected]) 2 , Agustín Enciso 2 , David A. Contreras-Solorio ([email protected]) 2 , Luis M. Hernández 1 1 Facultad de Física, Universidad de La Habana, Colina Universitaria. 10400, La Habana. Cuba. 2 Unidad Académica de Física, Universidad Autónoma de Zacatecas, Calzada Solidaridad Esquina con Paseo La Bufa s/n, C.P. 98060, Zacatecas, ZAC., México. The dilute nitride (GaIn)(NAs) is a novel material system grown lattice matched to GaAs. The band gap of GaAs decreases rapidly with the addition of small atomic fractions of N, moreover, the addition of In to GaNAs does not only provide a lattice matched to GaAs, but also decreases the band gap. This property makes very attractive the use of GaInNAs materials to fabricate multiple quantum wells and superlattice to improve the GaAs solar cell conversion efficiency. In the present work a GaAs p-i-n solar cell is modeled where the iregion is filled with GaAs/GaInNAs Gaussian superlattice (GSL), the barriers width is modulated by a Gaussian function. These systems have the outstanding characteristic that the transmission spectrum presents transparency bands or passbands with almost perfect transmission. Using transfer matrix method the tunneling probability as a function of energy was calculated for GSL. The results show that the spectrum is not substantially distorted by the presence of the applied electric field. We have used expressions to evaluate the density of states (DOS) and absorption coefficient corresponding to a GSL under the influence of an electric field perpendicular to the layers. With the increment of the electric field, the DOS value is diminished, meanwhile the absorption coefficient is not substantially modified. The photocurrent was evaluated and our results show that it can reach values which have never been obtained before for a single junction solar cell. The GSL solar cell conversion efficiency was computed and it shows high values. Because of the results that our model predictions are neither compared nor confirmed experimentally, it would be interesting to see if future experiments will corroborate our outcomes. 339 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-138 ] Pulsed laser deposition of non-stoichiometric CdO and the effect of annealing J.G. Quiñones-Galván ([email protected]) 3 , R. Lozada-Morales 6 , S. Jiménez-Sandoval 2 , Enrique Camps 5 , V.H. Castrejón-Sánchez 5 , V.H. Castrejón-Sánchez 7 , V.H. Castrejón-Sánchez 8 , E. Campos-González 4 , M. Zapata-Torres 1 , A. Pérez-Centeno 3 , M.A. Santana-Aranda 3 1 CICATA-IPN, Unidad Legaria, Mexico D.F.11500, Mexico Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Unidad Querétaro, Apartado Postal 1-798 Querétaro, Qro, 76001, Mexico. 3 Departamento de Física, Centro Universitario de Ciencias Exactas e Ingenierías, Universidad de Guadalajara, Boulevard Marcelino García Barragán 1421, Guadalajara, Jalisco, Mexico, C.P. 44430 4 Departamento de Física, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, P.O. Box 14-740, México D. F., 07360, Mexico 5 Departamento de Física, Instituto Nacional de Investigaciones Nucleares, Apartado postal 181027, Mexico D.F., C.P. 11801 6 Facultad de Ciencias Físico-Matemáticas, Postgrado en Física Aplicada, Benemérita Universidad Autónoma de Puebla, Av. 14 sur y Av. San Claudio, Col. San Manuel, Puebla, Mexico 7 Facultad de Química, Universidad Autónoma del Estado de México, Paseo Colón y Tollocan, Toluca, Mexico, C.P. 50110 8 Tecnológico de Estudios Superiores de Jocotitlán, carretera Toluca-Atlacomulco Km. 44.8, Ejido de San Juan y San Agustín, Jocotitlán, Mexico, C.P. 50700 2 By means of pulsed laser deposition, a CdO film was grown onto a glass substrate at room temperature. The mean kinetic energy and the ion density of the laser produced plasma were 75 eV and 13.5 x 10-12 cm-3 respectively. A laser fluence value of 2 J/cm2 was used. The film was thermally treated at 500 ºC in air, in order to see the effect of annealing on its physical properties. The structural properties of the as-grown film indicate that a (200) highly oriented polycrystalline cubic sample was obtained, which was confirmed by transmission electron microscopy. The annealed sample is still cubic but it is no longer oriented in the (200) direction. A reduction in grain size for the annealed sample was observed by scanning electron microscopy. Raman spectroscopy revealed the typical second order vibrational modes of cadmium oxide which are related to defects. XPS results show the presence of CdO together with a substoichiometric CdOx phase for the as-grown sample. For the annealed sample a compensation of oxygen vacancies was observed. Electrical resistivity measurements give a value of 8.602 x10-4 (Ω cm) for the as-grown film which is in excellent agreement for cadmium oxide films obtained by physical vapor deposition techniques. For the annealed sample the electrical resistivity increased to a value of 9.996 x 10-3 (Ω cm). The as-grown sample has zero transmission in the UV-Visible range as shown by optical transmission measurements. The photoluminescence spectra of the samples were measured in order to shed some light on the origin of the zero transmission result. 340 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-139 ] Structural and optical properties of copper selenide films grown by co-evaporation Arlette Casasanero Meléndez ([email protected]) 1 , Jorge Sastré Hernández 3 , Ma. de los Ángeles Hernández Perez 2 , Jorge R. Aguilar Hernández ([email protected]) 1 , Gerardo S. Contreras Puente 1 1 ESFM, IPN, Edificio de Física Avanzada, U. P. A. L. M. Col. Lindavista, México, D. F., C. P. 07738 2 ESIQIE, IPN, Edificio no. 8, U. P. A. L. M. Col. Lindavista, México, D. F., C. P. 07738 3 ITESM, Edificio de Física Avanzada, U. P. A. L. M. Col. Lindavista, México, D. F., C. P. 07738 In this work we present the results of characterization of copper selenides films grown by coevaporation. The substrate temperatures were 300 ºC and 400 ºC. Characterization of samples was carried out by means of SEM, XRD, EDS and UV-Vis studies. We obtained rich copper polycrystalline films; the main phases for the 400 ºC set are Cu2-xSe and Cu2Se, on the other hand, Cu7Se4, Cu2-xSe and Cu2Se are the main phases of the 300 ºC set. Copper atomic percentage is approximately 60 % for both sets of samples. Through UV-Vis transmission spectrum we determined that the films are direct band gap semiconductors and the band gap values are in the range of 1.12-1.46 eV. [ SEM-162 ] Plasmon-phonon coupling in graphene superlattices on polar substrates Gerardo Gonzalez de la Cruz ([email protected]) 1 1 Fisica, CINVESTAV-IPN , Apartado Postal 14-740 Mexico, D.F. We investigate the role of substrates on the collective excitations of layered graphene using the self-consistent field approximation. Specifically, we consider graphene layers adsorbed on polar materials as representative examples of semiconducting and oxide substrates. A new set of spectrum plasmons originate from the coupling between charge carrier plasmons in layered graphene structures and optical surface phonon of substrate. It is shown that the plasmon modes in double-layer graphene structures split into one acoustic mode (w~q) and two distinct optical modes which one of them displays a behavior more like a phonon mode 341 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla while the other one vanishes in the long wavelength limit and behaves similar to the optical plasmon mode present in spatially separated double-layer graphene. On the other hand, the surface plasmon mode in multilayer graphene coupled via Coulomb interaction with the polar substrate is discussed in the long wavelength limit and in the weak coupling limit such that qd>1 where d is the graphene layer separation. [ SEM-164 ] Synthesis and Characterization of Ga2S3 Thin Films Deposited by Pulsed Laser Deposition at Different Pressures Carlos Augusto López Lazcano ([email protected]) 2 , Gibran Guadalupe Martínez Falomir 2 , Ramon Alvaro Vargas Ortíz 2 , Manuel Quevedo López 1 , Susana Paola Arredondo Rea 2 , José de Jesus Campos Gaxiola 2 , Jorge Luis Almaral Sánchez 2 1 Department of Materials Science and Engineering, University of Texas at Dallas, Richardson, TX, 75080, USA 2 Facultad de Ingeniería Mochis, Universidad Autónoma de Sinaloa, Fuente de Poseidón y Ángel Flores s/n, Ciudad Universitaria, C.P. 81223, Los Mochis, Sinaloa, México. Thin films of gallium sulfide (Ga2S3) were deposited on glass substrates and silicon by the technique of pulsed laser deposition (PLD). For deposits, a target of Ga2S3 was used with a purity of 99.99% and Ar gas inside the general chamber of the equipment. The deposits were made at different pressures of Ar gas of 0.1 mTorr, 1 mTorr, 10 mTorr, 50 mTorr and 100 mTorr. The thin films obtained have good adhesion, uniform thickness and were free from microcracks. The films were characterized by Raman diffraction, Rutherford Backscattering Spectroscopy (RBS) and x-ray diffraction. XRD results observed that the films have an amorphous structure, indicating a disordered XMMX packing layers. Raman spectroscopy shows characteristic curves of Ga2S3 with a mainly monoclinic structure due to vibrations at 224 cm-1 (Vs-GaS4 (A1)) and 300 cm-1 (Vd-GaS4 (A ')). Analysis RBS shows that the thin films have an atomic ratio of Ga: S = 40:60 indicating that the PLD technique provides high chemical purity films. The above results show that the PLD technique is successful for growing stoichiometric Ga2S3 amorphous thin films, with high purity and good quality. Keywords: Ga2S3, Pulsed Laser Deposition, Semiconductor, Thin Film. 342 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-165 ] Synthesis and Characterization of ZnS Thin Films Deposited by PLD at different pressures Gibran Guadalupe Martínez Falomir ([email protected]) 2 , Carlos Augusto López Lazcano 2 , Ramón Alvaro Vargas Ortíz 2 , Manuel A. Quevedo López 1 , Adriana Cruz Enríquez 2 , Ramón Corral Higuera 2 , Jorge Luis Almaral Sánchez 2 1 Department of Materials Science and Engineering, University of Texas at Dallas, Richardson, TX, 75080, USA 2 Universidad Autónoma de Sinaloa, Facultad de Ingeniería Mochis, Fuente de Poseidón y Ángel Flores s/n, Ciudad Universitaria, C.P. 81223, Los Mochis, Sinaloa, México Thin zinc sulfide films are successfully deposited on glass and silicon substrates using pulsed laser deposition (PLD) at room temperature under different pressures of argon gas (0.1, 1, 10, 50 and 100 mTorr) and 200 oC at 10 mTorr pressure. For depositions was used a ZnS target with a purity of 99.99%, argon gas was used in general chamber at PLD. Argon influence on optical, structural and morphological properties thin films of zinc sulphide (ZnS), was investigated. The films were characterized by SEM, RBS and Raman. The SEM showed us the thickness of 100 nm, and the microstructural morphology was obtained, in which grain distribution on the substrate for film formation is seen. The Raman vibrational modes corresponding to ZnS a displacement of 300 cm-1 and a characteristic vibrational mode of S to 60 cm-1 they were shown. The RBS showed us only the elements present in the films, Zn and S, which were contained on target. XRD results indicate that the films have an amorphous structure with small crystalline at room temperature, to the deposition made at 200 oC has a higher crystallinity. In this study, the film deposited at a pressure of 10 mTorr to 200 oC is optimal for better crystallinity and better microstructural system and indicates that the PLD technique provides high purity films. Keywords: Semiconductor, Thin film, Zinc sulfide, pulsed laser deposition. 343 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-168 ] TiO2@G photoelectrodes sensitized with natural pigments for reduction of ammonia in aquaculture tanks with visible light Julio Omar Arias Ortiz ([email protected]) 2 , Erick Esaú Hernández Santiago 5 , Oscar Aarón Márquez González 5 , Rafael Valentín Tolentino Hernández 5 , Francisco Javier Espinosa Faller 3 , Mariel Gullian Klanian 3 , Octavio Calzadilla Amaya 1 , Kamaraj Sathish Kumar 4 , Fabio Felipe Chalé Lara 2 , Felipe Caballero Briones ([email protected]) 2 1 Facultad de Física, Universidad de La Habana. San Lázaro y L, Vedado. 10400 La Habana, Cuba 2 Laboratorio de Materiales Fotovoltaicos, Instituto Politécnico Nacional CICATA Altamira, Km 14.5 Carretera Tampico-Puerto Industrial Altamira, 89600 Altamira, México 3 Unidad Experimental Marista, Universidad Marista de Mérida. Periférico Norte Tablaje Catastral 13941 Carretera Mérida-Progreso. 97300 Mérida México 4 Universidad Politécnica de Aguascalientes, Ingeniería en Energía Calle Paseo San Gerardo No. 207. Fracc. San Gerardo. Aguascalientes, Ags. México, 20342 5 Universidad Tecnológica de Altamira, Blvd. de los Ríos Km. 3+100, Puerto Industrial Altamira, 89608 Altamira, México The degradation of waste nitrogen compounds produced in aquaculture tank is commonly done through the usa of biofilters (among other methods) to avoid ecosystem poisoning. An alternative method is TiO2-based photocatalyst to degrade NH3 into N2. On the other hand, graphene is a material with a high charge transport efficiency which is proposed to enhance the photocatalyst system efficiency. In this work TiO2 and TiO2@G films were made by Pechini method onto Fluorine-doped Tin Oxide (FTO), Aluminium-doped Zinc Oxide (AZO), Stainless Steel (SS) and Soda Lime Glass (SLG) substrates. The molar ratios in the Pechini solution were 20:5:1 of titanium isopropoxide, citric acid and ethylene glycol respectively. A mixture of Pechini-TiO2pm25 nanopowder was made and ultrasonically dispersed until a paste is formed and therefore the paste was deposited on FTO and SS substrates (≈1cm2) by doctor blade technique and lately calcined up to 450 °C. Some of the electrodes were impregnated with the ethanolic extract of Laburnum anagyroides Medic. known as golden rain tree to sensitize it to visible light. Films were characterized by Reflectance Spectroscopy (RS), X Ray Diffraction (XRD), and current-voltage (I-V) and photodegradation activity with methylene blue. The results are discussed in terms of substrate type, graphene presence and sensitization. Financed by SIP 20151074 and CONACYT 169108 344 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-172 ] X-ray diffraction studies of CuCdTeO films deposited at room temperature Martín Adelaido Hernández Landaverde ([email protected]) 1 , Alejandro Montañéz Delgado 1 , Francisco Rodríguez Melgarejo 1 , Gabriel López Calzada 1 , Sergio Jiménez Sandoval 1 1 Centro de Investigación y de Estudios Avanzados del IPN, Unidad Querétaro, Mexico. A detailed X-ray diffraction study was carried out on CuCdTeO films deposited by radio frequency sputtering at room temperature. The use of low growth temperatures is appealing in the search for inexpensive processes for the growth on technologically important materials. CuCdTeO films are interesting semiconductor materials because of their ease in tailoring their optical and electrical properties by varying the relative concentrations of the elemental constituents. The CuCdTeO films were prepared from targets made of mixtures of CdTe and CuO powders through cold-pressing processes. The CuO concentrations used in the target preparation ranged from 0 to 25 at.%. All the films were deposited on Corning 2947 glass substrates. Glancing angle X-ray diffraction measurements were performed on each of the as-grown films. Notwithstanding the fact that the substrates were not intentionally heated, all the films showed polycrystalline characteristics with significant preferential orientation. The effect of the various [CuO] concentrations on the crystalline structure (i.e. relative abundance of zincblende and wurtzite phases), preferential orientation characteristics and crystalline quality are presented and discussed. 345 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-184 ] Optical and structural characterization of polycrystalline zinc-selenide thin films grown by pulsed laser deposition Patricia Maldonado-Altamirano ([email protected]) 1 , Luis Arturo Martínez-Ara 1 , María de los Ángeles Hernandez-Perez 2 , Jorge AguilarHernandez ([email protected]) 1 , Gerardo Contreras-Puente 1 , Fray de Landa Castillo-Alvarado 1 1 2 ESFM-IPN Edificio No. 9 UPALM Lindavista C. P. 07738, México D. F ESIQIE-IPN Edificio No. 7 UPALM Lindavista C. P. 07738, México D. F In this paper results of the processing and characterization of polycrystalline thin films of the binary semiconductor compound zinc-selenide (ZnSe) grown onto glass, quartz and crystalline silicon are presented. ZnSe films were processed by Pulsed Laser Deposition (PLD) technique, under the following conditions: substrate temperature Ts =400 °C, deposition time td = 30 min, pressure in the growth chamber P = 1.2x10 -6 Torr, laser = 1064 nm, and repetition frequency 50 Hz. Structural and optical properties of the films were studied by X-ray diffraction, scanning electron microscopy (SEM), UV-Vis absorption, photoluminescence (PL) and Raman spectroscopy. From the analysis of the absorption spectra the value of the band gap Eg = 2.5 eV was obtained. The X-ray diffraction patterns exhibit maxima at 2 = 27.4, 45.5 and 53.76, corresponding to the zinc-blende structure, a small diffraction peak at 2 = 25.7 was also observed, it corresponds to the (010) plane of the wurzite structure. The samples also exhibited room temperature luminescence, which allowed us to carry out a PL study as a function of temperature, 10-300 K, in order to be able to assign the radiative transitions; a deep PL analysis is also presented. The observed Raman features have been related to multiple optical phonon (1LO to 3LO) light scattering. 346 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-189 ] Optical and structural study of GaN grown by pulsed laser deposition in nitrogen atmosphere Luis Arturo Martínez Ara ([email protected]) 1 , Jorge Ricardo Aguilar Hernández ([email protected]) 1 , María de los Ángeles Hernández Pérez 2 , Gerardo Silverio Contreras Puente 1 1 2 ESFM-IPN Edificio No. 9 U. P. A. L. M. Lindavista C. P. 07738, México D. F. ESIQIE-IPN Edificio No. 7 U. P. A. L. M. Lindavista C. P. 07738, México D. F. Results about processing and characterization of gallium nitride (GaN) films grown by pulsed laser deposition technique are presented. The films were grown on sapphire (0001) and silicon (100) substrates, under the following conditions: substrate temperature 850 ° C, time deposition of 2 minutes, pressure of torr. A Nd: YAG laser was used with =1064 nm, repetition frequency of 50 Hz and power of 2.8 W. To characterize GaN films, diffraction X rays, UV-Vis spectroscopy and photoluminescence were used. To study the GaN films structural properties, X-ray diffraction was used obtaining peaks corresponding to GaN and trace Ga2O3. To study the optical properties, UV-Vis spectroscopy absorption and photoluminescence were used. From the UV-Vis spectroscopy a band-gap value of 3.2 eV was obtained. Photoluminescence at room temperature was observed, which allow perform the study at low temperature, the results of this study are also presented in this work. 347 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-191 ] Development of planarized ambipolar aSiGe:H Thin-film Transistors Technology Miguel A. Dominguez Jimenez ([email protected]) 1 , Pedro Rosales Quintero 2 , Alfonso Torres Jacome 2 , Mario Moreno Moreno ([email protected]) 2 , Jose A. Luna Lopez 1 , Salvador Alcantara Iniesta 1 , Susana Soto Cruz 1 1 Centro de Investigaciones en Dispositivos Semiconductores, Instituto de Ciencias, Benemerita Universidad Autonoma de Puebla (BUAP). Puebla, Mexico. 2 Instituto Nacional de Astrofisica, Optica y Electronica (INAOE), Departamento de Electronica. Puebla, Mexico. Electronic devices fabricated on flexible and large-area substrates are of great interest for the research community. Thin-film transistors (TFTs) have a high potential to be integrated in this technology due to its low-temperature process. Although complementary logic circuits based on discrete n- and p-type transistors are currently under development, the use of ambipolar TFTs that work as both p- and n-type transistors can simplify the design and reduce the cost of the complementary logic circuits. An alternative semiconductor for obtaining ambipolar TFTs fabricated at low temperature is hydrogenated amorphous silicongermanium (a-SiGe:H). This film is barely used as an active layer in TFTs, since a high content of germanium increases the density of states in the film. However, a low incorporation of germanium improves some properties of the a-Si:H films, such as electron and hole mobilities. Our a-SiGe:H films have estimated electron and hole mobilities of the same magnitude, which indicates a possible candidate for ambipolarity. Since one of the bottlenecks in this technology is the source/drain contact resistance, different processes have been implemented in order to improve the main device interfaces. Previously in literature, a reduction of the contact resistance has been attributed to the planarization of the gate electrode. In order to provide a physical explanation of this improvement, the electrical performance of ambipolar a-SiGe:H TFTs with planarized gate electrode by Spin-On Glass is compared with unplanarized ambipolar a-SiGe:H TFTs, and the properties in the main device interfaces are analyzed by physically-based simulations. Also, trap density and characteristic energies for the deep localized states in the a-SiGe:H film are obtained. Finally, using these parameters the device modeling is presented. 348 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-192 ] Zinc Oxide Thin-film Transistors Technology by Ultrasonic Spray Pyrolysis Miguel A. Dominguez Jimenez ([email protected]) 1 , Francisco Flores Gracia 1 , Adan Luna Flores ([email protected]) 1 , Jose A. Luna Lopez 1 , Salvador Alcantara Iniesta 1 , Susana Soto Cruz 1 , Pedro Rosales Quintero 2 , Mario Moreno Moreno 2 1 Centro de Investigaciones en Dispositivos Semiconductores, Instituto de Ciencias, Benemerita Universidad Autonoma de Puebla (BUAP). Puebla, Mexico. 2 Instituto Nacional de Astrofisica, Optica y Electronica (INAOE), Departamento de Electronica. Puebla, Mexico. Currently, Zinc Oxide (ZnO) films are attractive to be an alternative to amorphous silicon in thin-film transistors (TFTs) commercial applications. ZnO films can be obtained by several techniques such as pulsed laser deposition, sputtering, chemical vapor deposition, etc. Although some of these techniques allow the deposition of oxide films at room temperature, they present some technical problems such as low compatibility with large-area substrates and high-cost. On the other hand, spray pyrolysis offers low-cost, simplicity, compatibility with large-area substrates and no need of high vacuum. These advantages make of great potential the use of oxide semiconductors by spray pyrolysis as active layer in TFTs for transparent, flexible and large-area applications. Although, oxide TFTs fabricated by spray pyrolysis have already been demonstrated, the temperature of deposition to obtain high performance devices is still high to be compatible with most of the low-cost plastic substrates used in the aforementioned technologies. Then, it is necessary reduce the temperature of deposition at values about 200°C or less in order to be a real alternative for large-area and flexible applications. In this work, it was used an ultrasonic humidifier and air as carrier gas to spray the precursor solution onto the TFT structures. The application of ZnO films obtained by ultrasonic spray pyrolysis at low-temperature (200°C) as active layer in TFTs is presented, as well, the impact of the gate dielectric thickness and active layer thickness in the electrical performance of the ZnO TFTs. Also, the annealing effects at 180°C in the Aluminum-ZnO contacts as function of time were studied. Finally, using a physically-based simulator (SILVACO), the density of states DOS is modeled to reproduce the experimental electrical characteristics of ZnO TFTs fabricated by Ultrasonic Spray Pyrolysis. The contact resistance was experimentally extracted from the ZnO TFTs and included into the simulation, in order to separate the metal-semiconductor interface contribution from the DOS. A comparison between the modeled DOS considering the contact resistance and disregarding it is also presented. 349 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-196 ] Growth of ZnTe and CdTe nanolayer on GaSb and GaAs (100) oriented substrates by Atomic Layer Deposition Miguel Galvan-Arellano 2 , Joel Díaz-Reyes ([email protected]) 1 , Mario Alberto Flores González 4 , Mario Villanueva-Ibañez 3 , Roberto Saul Castillo-Ojeda 3 1 Centro de Investigación en Biotecnología Aplicada, Instituto Politécnico Nacional. Ex– Hacienda de San Juan Molino, Km. 1.5. Tepetitla, Tlaxcala. 90700. México. 2 Depto. de Ingeniería Eléctrica, SEES, CINVESTAV-IPN. Apartado Postal 14-740, México, D.F. 07000. México. 3 Universidad Politécnica de Pachuca, Km. 20, Rancho Luna, Ex-Hacienda de Santa Bárbara, Municipio de Zempoala, Hidalgo. 43830. México 4 Universidad Politécnica de Pachuca, Km. 20, Rancho Luna, Ex-Hacienda de Santa Bárbara, Municipio de Zempoala, Hidalgo. 43830. México. Among the most successful materials for the detector fabrication are the ZnTe, CdTe and their respective alloy Cd1-XZnXTe (CZT). These materials in its nanostructured forms are promising for the production of potential new electronic devices. In addition, it is well known the high detective quantum efficiency of these materials. With the discovery of the new properties arising from the nanostructured materials, the growth of nanolayers and nanostructured materials has gained great importance. ZnTe, CdTe and their alloys, have proved to be a very important materials for application in this field. Moreover it is possible to take advantage of the properties of III-V materials as GaAs and GaSb when are used as substrates of these layered structures. GaSb is an important material used extensively for the infrared radiation detection. In addition, the lattice parameter is close to the ZnTe, making it very attractive for its use as substrate; however, it is well known that GaSb surface is rapidly oxidized introducing additional difficulties for its use. GaAs has been extensively studied IIIV material, with important optical and electrical properties, which can be exploited for device fabrication in conjunction with the CZT structures. In this work are presented the result obtained of the growth of ZnTe and CdTe nanolayers on GaSb and GaAs by Atomic layer Deposition. The results included are Raman spectroscopy and HRXRD in order to study the crystalline quality and optical properties. 350 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-198 ] Optical characterization of thin films of amorphous Cd1-xPbxS from transmittance measurements Jorge I. Contreras-Rascón 4 , Joel Díaz-Reyes ([email protected]) 1 , Miguel Galván-Arellano 2 , Verónica Márquez Buendía 3 1 Centro de Investigación en Biotecnología Aplicada, Instituto Politécnico Nacional. ExHacienda de San Juan Molino, Km. 1.5. Tepetitla, Tlaxcala. 90700. México. 2 Depto. de Ingeniería Eléctrica, SEES, CINVESTAV-IPN. Apartado Postal 14-740, México, D.F. 07000. México. 3 Instituto Tecnológico de Tehuacán. Libramiento Tecnológico S/N, A.P. 247, Tehuacán, Puebla. 75770. México. 4 Universidad de Sonora, División de Ciencias Exactas y Naturales, Col. Centro, Hermosillo, Sonora. 83000. México. This paper presents the study of the optical constants of Cd1-xPbxS thin films prepared by chemical bath deposition in spectral range from 300 to 2600 nm, using interferential fringes of the transmittance spectrum of the film-substrate system. Refractive index, the films thickness and the absorption coefficient are calculated following Swanepoel´s method. The dispersion of the refractive index is explained using the single harmonic oscillator WempleDiDomenico model. The absorption edge is found according to the model proposed by Tauc, from which the value of the optical gap is obtained, also obtaining the optical band gap values. 351 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-199 ] Growth and characterization of chemicalbath deposition Cd1-xPbxS Froylán Ángel Huerta 3 , Joel Díaz-Reyes ([email protected]) 1 , Jorge I. Contreras-Rascón 4 , Miguel Galván-Arellano 2 , José Francisco Sánchez-Ramírez 1 1 Centro de Investigación en Biotecnología Aplicada, Instituto Politécnico Nacional. ExHacienda de San Juan Molino, Km. 1.5. Tepetitla, Tlaxcala. 90700. México. 2 Depto. de Ingeniería Eléctrica, SEES, CINVESTAV-IPN. Apartado Postal 14-740, México, D.F. 07000. México. 3 Escuela Superior de Ingeniería Mecánica y Eléctrica, Unidad Culhuacán. Instituto Politécnico Nacional. Av. Santa Ana 1000, Col. San Francisco Culhuacán, Del. Coyoacán, México, D.F. 04430. México 4 Universidad de Sonora, División de Ciencias Exactas y Naturales, Col. Centro, Hermosillo, Sonora. 83000. México. The development of third-generation solar cells overcoming the Shockley−Queisser efficiency limit for a single absorber, 31%, is one of the most fascinating challenges in the energy research field. In this aspect, semiconductor quantum dots (QDs) have shown extremely attractive properties for the development of solar cells overcoming the current limitations. The demonstration of an efficient multiple exciton generation (MEG) process in colloidal QDs, despite certain controversy, has aroused a huge interest in the use of these materials in photovoltaic devices. This interest has been reinforced with the recent reports of absorbed photon-to-current efficiency (APCE) close to 200% and incident photon-to-current efficiency (IPCE) as high as 114%. These achievements are acquired by using QDs with IR absorption, PbS and PbSe. In the former case PbS QDs have been employed in a sensitized solar cell configuration. An attempt was made to modify the band gap of CdS (~2.4 eV) by preparing a mixed lattice with a low-band-gap material, PbS (0.3 eV), giving a new set of materials, CdxPbl-xS. Band gaps as low as -~ 1.9 eV were achieved with increasing x. The preparation of CdxPbl-xS was carried out by chemical-bath deposition. Structural characterization studies using X-ray diffraction (XRD), energy dispersion analysis by X-rays (EDAX), and optical microscopy were performed. The optical-absorption studies used to find the band gap are also described. The CdxPbl-xS chemical stoichiometry was estimated by EDS. The deposited CdxPbl-xS showed hexagonal wurtzite crystalline phase, which was found by X-ray diffraction and confirmed by Raman spectroscopy. 352 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-200 ] Optical and structural characterization of CdSe1-ySy deposited at low-temperature by chemical bath deposition Jorge I. Contreras-Rascón 4 , Joel Díaz-Reyes ([email protected]) 1 , Miguel Galvan-Arellano 2 , Luis Alberto Juárez-Morán 3 1 Centro de Investigación en Biotecnología Aplicada, Instituto Politécnico Nacional. Ex– Hacienda de San Juan Molino. Km. 1.5. Tepetitla, Tlaxcala. 90700. México. 2 Depto. de Ingeniería Eléctrica, SEES, CINVESTAV-IPN, Apartado Postal 14-740, México, D.F. 07000. México. 3 Facultad de Ciencias Fisicomatématicas, Benemérita Universidad Autónoma de Puebla. Av. San Claudio y 18 Sur. Col. San Manuel, Ciudad Universitaria. Puebla, Puebla. 72570. México 4 Universidad de Sonora, División de Ciencias Exactas y Naturales, Col. Centro, Hermosillo, Sonora. 83000. México. We present the structural and optical characterization of cadmium selenide sulphur (CdSe1ySy) deposited by chemical bath deposition (CBD) technique on glass at a low-temperature (20±2°C). The sulphur molar fraction is varied from 0 to 42.13%. The CdSe1-ySy chemical stoichiometry is estimated by energy-dispersive X-ray spectroscopy (EDS). The CdSe1-ySy shows hexagonal wurtzite crystalline phase, which is found by X-ray diffraction (XRD) analysis and it is confirmed by Raman spectroscopy. The average grain size of the CdSe1-ySy films were in the range from 1.199 to 1.683 nm that were determined by Debye-Scherrer equation from W(002) direction and was confirmed by high resolution transmission electron microscopy (HRTEM). This average grain size indicates a high quantum confinement due to which is smaller than the Bohr radii of CdS (2.8 nm) and CdSe (4.9 nm). Raman spectra show two dominant vibrational bands about 208 and 415 cm-1 associated at CdSe-1LO-like and CdSe-2LO-like. By transmittance measurements at room temperature is found that the optical bandgap energy varies from 1.86 to 2.158 eV in the range of investigated sulphur molar fraction. The room temperature photoluminescence presents radiative bands in visible and a dominant radiative band about 3.0 eV that may be associated exciton bound to donor impurity. 353 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-218 ] Photocatalytic degradation of Methyl Red dye in aqueous solution under UV and solar radiation using Au doped TiO2 R. Hernández ([email protected]) 2 , C. Guzmán 2 , S. M. DurónTorres 2 , K. Esquivel 1 , E. A. Elizalde 1 , A. Domínguez 1 1 Facultad de Ingeniería, Universidad Autonónoma de Querétaro, Cerro de las Campanas, C.P. 76000, Santiago de Querétaro, Qro., México 2 UACQ – UAZ, CU Siglo XXI Edificio 6, Km 6 Carr. Zac – Gdl, La Escondida Zacatecas, Zac, C.P. 96160, México Water pollution is a problem that affect us all, leaving no choice but to seek ways to make contaminated water again be fit for human consumption. Photocatalytic processes received great attention in wastewater treatment due to its cheapness, environmental compatibility and optimal performances. Because of this reason, the present contribution aims to deepen the knowledge in Au doped TiO2-based systems and their employment in methyl red removal from aqueous solutions. Au-TiO2 photocatalysts have been synthetized by a microwave assisted sol-gel method and characterized by means of X-ray diffraction techniques (XRD). Depending on the weight percentage of dopant (0.01 wt%, 0.05 wt%, 0.1 wt%, 0.5 wt%, 1.0 wt%, 5 wt%), some changes in the band gap energy can be observed. X-ray diffractions patterns were recorded to study the formation of TiO2 crystalline species. The diffraction peaks detected after the calcination process indicates the presence of the crystalline anatase phase and no presence of rutile phase was observed. For the Au-TiO2 sample, the peaks detected in 2θ (38°, 44.2°, 64.4°, 77.2°) indicates the presence of particles of metallic gold. The catalytic activity was evaluated with respect to methyl red photodegradation in different conditions as a function of irradiated light (UV, solar), application of an electric current, the combination of both processes and different concentrations of methyl red aqueous solutions. The photocatalytic test demonstrate the positive influence of the application of an electric current to photocatalytic processes. A complete bleaching of the solution was achieved at 20 min using a photoelectrocatalytic method whilst the conventional photocatalytic method didn’t bleach completely at 90 min of reaction and a conventional electro oxidation method achieve the complete bleaching at 40 min of reaction. 354 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-221 ] Size controlled synthesis of In2O3 microcrystals of octahedral shape in vapor-solid growth process Jesús Alberto Ramos Ramón ([email protected]) 2 , Rutilo Silva González 2 , Efraín Rubio 1 , Umapada Pal 2 1 Centro Universitario de Vinculación y Transferencia de Tecnología (CUVyTT), Universidad Autónoma de Puebla, 24 Sur, C.U., Puebla 72570, México. 2 Instituto de Física, Universidad Autónoma de Puebla. Apdo. Postal J-48, Puebla, Pue., México Micro-/nanometer indium oxide (In2O3) particles of octahedral shape were synthesized through vapor-solid (VS) method varying the growth conditions, such as growth temperature (640, 750 and 850 °C) and heating rate (10, 20, 40 and 60 °C/min) using a high temperature horizontal furnace. A mixture of In + graphite powder was used as precursor, and Ar + O2 (10:1 v/v, 220 sccm) mixture was used as carrier cum reactive gas. The quartz substrates used as support were put downstream at the lower temperature zone. The morphology and size of the micro-/nanostructures were analyzed by scanning electron microscopy (SEM). The composition of the particles was estimated by energy-dispersive spectroscopy (EDS). The crystallinity and optical properties of the particles were analyzed using microRaman spectroscopy at room temperature. It has been observed that both the heating rate and growth temperature affect the final size of the microcrystals without affecting their crystallinity. We acknowledge the financial supports extended by CONACyT, Mexico (Grant # CB2010/161767), and VIEP, BUAP (Grant# VIEP/EXC/2015), Mexico for realizing this investigation. 355 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-226 ] Paving the way for an increased photocatalytic performance of TiO2 in the visible spectral region by surface chemical modification Adan Luna-Flores ([email protected]) 1 , Adan Luna-Flores 3 , José Luis Sosa-Sánchez 1 , Maritza Méndez-Hernández 3 , Javier Martínez-Juárez 1 , María Josefina Robles-Águila 1 , Ligia Catalina Muñoz-Arenas 2 1 Centro de Investigación en Dispositivos Semiconductores del IC-BUAP, 14 sur y Av. San Claudio, Ciudad Universitaria, Puebla, Pue. A.P. 196, C.P. 72000, MÉXICO 2 Facultad de Ciencias Biotecnoambientales, UPAEP, 21 Sur 1103 Barrio Santiago, Puebla, Pue. C.P. 72410, MÉXICO 3 Facultad de Ingeniería Química, Benemérita Universidad autónoma de Puebla, Av. San Claudio y 18 Sur, Ciudad Universitaria, Puebla, Pue. C.P. 72570, MÉXICO Keywords: Advanced Oxidation Processes, Surface Modified Photocatalyst, Phthalocyanine Dyes. Recently developed Advanced Oxidation Processes -AOPs- show a great potential for application in many wastewater treatment procedures. In a general context, AOPs refer to an emerging technology consisting of chemical procedures designed to remove organic and sometimes inorganic materials in water and wastewater by oxidation reactions with hydroxyl radicals (•HOs). These AOPs utilize the very strong oxidizing power of these radical species generated “in situ” to oxidize organic compounds, in the best case scenario, to the end products of carbon dioxide and water. In the follow-up of an ongoing project, we present our results on the degradation of Rhodamine B using a new TiO2 photocatalyst which was modified on its surface with Al to prevent charge carrier recombination. In addition, a tetracarboxylated zinc phthalocyanine dye -ZnPc- was incorporated onto the TiO2 surface as an antenna molecule in order to extend the catalyst photo-response to the visible range. In the modified photocatalyst system, the absorbed dye can inject electrons into the conduction band of the semiconductor after visible light excitation. On the other hand, the incorporation of the Al metal dopant results in an improved trapping of electrons that inhibits the electron-hole recombination during irradiation. The decrease of charge carriers recombination results in an enhanced photoactivity for the degradation of Rhodamine B. The degradation process was monitored by UV-Visible spectroscopy and comparison of the photocatalytic activity of three different materials TiO2, TiO2/Al y TiO2/Al/ZnPc under the same degradation conditions show an increased performance in the same order: 15%, 60% y 70% respectively. 356 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-232 ] Structural and Optical Characterization of InAsSb/GaSb Grown by Liquid Phase Epitaxy Yolanda Elinor Bravo-García ([email protected]) 2 , Patricia Rodríguez-Fragoso 3 , Julio Gregorio Mendoza-Álvarez 3 , Gerardo González de la Cruz 3 , Rogelio Fragoso-Soriano 3 , José Alberto AndracaAdame 1 1 CNMN-IPN FCE-BUAP 3 Physics Department-CINVESTAV 2 High quality InAs1-xSbx semiconductor films were successfully grown on (100) GaSb single crystal substrates using liquid phase epitaxy technique (LPE). The crystalline structure and lattice mismatch between film and substrate were investigated by high-resolution X-ray diffraction (HRXRD). The surface roughness and the interface morphology of the epitaxial film-on-substrate were characterized by atomic force microscopy (AFM), scanning electron microscopy (SEM) and optical microscopy. These results show the high-purity InAs1-xSbx epitaxial layers with mirror-like surface and rms ranges from 0.5 to 2 nm, and a sharp interface between substrate a ternary film. The optical properties of the layers were studied by low temperature photoluminescence (PL) spectroscopy. PL spectrum of the ternary film shows one radiative emission peak with narrow full width at half-maximum, which is an evidence of the good crystalline quality of the epilayer. It is worth to mention that the InAsSb films were grown on GaSb substrates for compositions of Sb with x=0.16 without introducing any intermediate composition buffer layer between the GaSb substrate and the film as reported in previous works. 357 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-242 ] Influence of pH on ZnO nanocrystalline thin films obtained by CBD method Bertha Luisa Rivera Flores ([email protected]) 1 , Reina Galeazzi Isasmendi 1 , Tomás Díaz Becerril 1 , Elia Viridiana Reyes Cervantes 1 , Nicolás Rutilo Silva González 2 , Enrique Rosendo Andrés 1 , Crisóforo Morales Ruiz 1 , Godofredo García Salgado 1 1 CIDS-ICUAP, Benemérita Universidad Autónoma de Puebla. Av. San Claudio y 14 Sur s/n C.U., Col. San Manuel, Edif. 103-C. Puebla, Pue., 72570, México. 2 Instituto de Física, Benemérita Universidad Autónoma de Puebla, Apdo. Postal J-48, Puebla, Pue. México. In this work, different formation of zinc oxide (ZnO) nanoparticles with wurtzite structure are reported. Semiconductors such as ZnO, ZnS, and ZnTe have extensive applications in electronics, photonics and photoelectronics. ZnO nanoparticles are of great interest in both scientific and technological point of view because of their novel electronic properties. ZnO nanocrystalline thin films have been prepared on glass substrates by using chemical bath deposition (CBD) method, at low temperature in aqueous solutions and varying the pH of precursor solutions from 8 to 11.5 under controlled growth conditions. The nanostructures obtained at low pH present a grow along c-axis in form of spindle. A higher pH of the reaction mixtures leads to a better definition of prismatic planes, forming bar-shaped structures. The analysis show that the surface morphology improves with increase of pH values. The structural, morphological and optical characterization were performed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence (FL) respectively. It was found that with the variation of the pH of the reaction solutions the morphology of ZnO nanostructures could be controlled. Keywords:ZnO nanostructures, CBD technique, Wurtzite structure. 358 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-245 ] Electric-Dipole Spin Resonance dynamics for an electron confined in a quantum dot Miguel Ángel Rodríguez Moreno ([email protected]) 1 , Lilia Meza Montes 2 , David Hernández de la Luz ([email protected]) 1 1 2 CIDS, BUAP IFUAP, BUAP Electric-dipole spin resonance or EDSR [1] provides an effective way for manipulating the electron spin as it has been demonstrated experimentally in nanolitographic quantum dots [2]. It is based on the spin-orbit interaction that couples the spin degree of freedom with the orbital motion when a time-dependent electric field and a static magnetic field are applied. Here, we present a detailed study of this dynamics for one electron in a single quantum dot. We numerically solve the time-dependent Schrödinger equation in order to analyze the evolution of an electron spin confined in a single quantum dot, including Rashba and linear Dresselhaus spin-orbit interactions. Rabi oscillations are observed and their dependence on different parameters is studied. An analytical approach based on Schrieffer-Wolff theory was also used, showing qualitative agreement with the numerical one within the limits of the perturbative approximation. Dependence on the orientation of the electric field with respect to the crystallographic axes is discussed and conditions for maintaining the system within an ideal two-level system are proposed. References [1] Rashba, E. I. and Efros, A. L., "Orbital mechanisms of electron-spin manipulation by an electric field". Phys. Rev. Lett. 91, 126405 (2003). [2] Laird E. A. et al., "Hyperfine-mediated gate-driven electron spin resonance". Phys. Rev. Lett. 99, 246601 (2007). 359 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-250 ] Photocatalytic activity of TiOx thick films prepaed by Dr. Blade method. E. Morales Ricardez 1 , M. Zapata-Torres ([email protected]) 2 , E. Valaguez Velázquez 4 , J.L. Fernández Muñoz 2 , O Calzadilla Amaya 3 1 CECYT 6 - IPN, Av. Jardin y calle 4 s/n , C.P. 02950, Mexico D.F. CICATA-IPN, Unidad Legaria, Legaria 694 C.P. 11500 D.F., México 3 Facultad de Física. Universidad de La Habana. San Lázaro y L. CP 10400. La Habana. Cuba 4 UPIITA-IPN, Av. IPN 2580 C.P. 07340 México, D.F. 2 TiO2 is a widely used photocatalyst with diverse applications such as air purification, deodorization, water purification and self-cleaning coatings. TiO2 is a wide band gap (3.2 eV) semiconductor material that shown photocatalytic activity under UV light irradiation. However, the UV radiation intensity in the solar radiation reaching surface earth is very faint, just around 5 % of the incident solar energy. Then, producing a photocatalytic TiO2 based material with a lower band gap could increase its efficiency. Finding novel photocathalytic semiconductor materials that absorb lower energy photons, in the visible and infrared regions of the solar spectrum, would allow to use a wider portion of the solar spectrum and as consequence increasing its effiency. Several studies have reported the red-shift of the band gap of TiO2 employing several approaches such as doping with diverse metals; doping with non metallic ions; dye sensitization; mixing with semiconductor quantum dots and nonstoichiometric mixed phase titania nanocomposites. The improved photoresponse in the visible region of the solar spectrum of Ti suboxides involves new energy levels of the semiconductor: Ti3+ defects enhance visible light photoactivity by introducing band-gap energy states. TiOx thick films have been deposited on ITO coating corning glass substrates, using Dr. Blade method. In order to obtain TiOx nanoparticles we used a ball milling of TiO2+NaBH. The TiOx nanoparticles were annealed at 500 °C in Ar atmosphere. The structural and chemical bond characteristics were analyzed by X- ray diffraction and X-ray photoelectron spectroscopy (XPS). UV-Vis diffuse reflectance spectroscopy was employed to determine the band gap energy. The photocatalytic efficiency was evaluated by the photodegradation of a methylene blue aqueous solution. The samples showed a photocatalytic activity in the visible or visible-NIR light spectrum. This work was supported by SEP CONACYT (projetc 153245) and SIP-IPN (project 20150090) 360 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-262 ] Optical and electrical characterization of HCl doping polyaniline Cesia Guarneros Aguilar ([email protected]) 1 , Miguel A. Dominguez Crespo 1 , Ana Bertha Lopez Oyama 1 , Edna Carina De la Cruz Terrazas 1 1 CICATA-IPN Unidad Altamira, Carretera Tampico-Puerto Industrial Altamira Km 14.5, Industrial Altamira, 896000, Altamira Tamaulipas, Mexico The most of semiconductors are crystaline inorganic solids, however, it has been demostrated that conjugated organics molecules can exhibit semiconductor behavior. The conducting polymers have specific properties such as high flexibility, high impact resistance and unique electronic-optical properties. As a consequence has a potential application in a variety of advanced devices ranging from organic electronics, sensors, batteries, actuators, thermoelectrics, to electro-optic and electro-chromatic devices. In this study, it is reported the synthesis and characterization of a series of HCl (0.5 M, 0.75 M and 1.0 M) doping polyaniline (PANI) by oxidative polymerization using ammonium persulfate (APS) as oxidant, and maintaining the reaction temperature in the range from 0° to 3° C. The asprepared samples were characterized using X-ray diffraction, IR and UV-vis spectroscopy in irder to know their structural and optical properties. The electrical characteristics were analyzed by Hall effect. XRD analysis indicates that all PANI samples exhibit typical crystalline peak at 25°, whereas the UV-vis spectra show the band absorption in the range from 240 to 320 nm asosiated to the HOMO-LUMO transition. Finally, the conductivity of PANI samples were about 6.2, 9.7 and 26.4 S/cm. 361 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-287 ] Preparation of hybrid material : metal phthalocyanine sensitized oxide semiconductors by soft chemistry for enviromental applications Maria Josefina Robles Aguila ([email protected]) 1 , Adan Luna Flores 2 , José Luis Sosa Sanchez 1 , Javier Martinez Juarez 1 1 2 Centro de Investigación en Dispositivos Semiconductores ICUAP-BUAP Facultad de Ingeniería Química, Benemérita Universidad Autónoma de Puebla Over the last few years, the search for novel nano materials with special physical and chemical properties has been an important challenge in the field of nanotechnology. A promising approach is to synergistically combine two or more nano materials into a hybrid structure. The hybrids systems TiO2/PcZn and ZnO/PcZn were prepared following a soft chemistry approach using a solvothermal method assisted by microwave radiation. Results from this study indicate that changing the irradiation time within the microwave oven, the reagents, the pH and the incorporation of a surfactant additive in the reaction medium affect the crystallinity of all the materials obtained. An asymmetric zinc-phthalocyanine complex of the A3B type was used for sensitization of the oxides semiconductors. Phthalocyanines (Pcs) are considered very attractive sensitizers because of their light-harvesting properties in the red and near-infrared (near-IR) spectral regions and this allows the use of solar radiation to activate the photocatalytic process. The performance of the system hybrids were evaluated by the photocatalytic degradation aqueous solutions of Rhodamide B for 240 minutes under irradiation visible light. 362 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-313 ] Sub-Wavelength Structured Silicon Films Deposited by RF-PECVD for Photovoltaics William W. Hernández-Montero ([email protected]) 1 , Carlos Zúñiga 1 , Javier De la Hidalga 1 , Wilfrido Calleja 1 , Adrián Itzmoyotl 1 1 Departamento de Electrónica, INAOE, Puebla, México Solar cell is the key element for the generation of electrical energy from solar radiation. Basically, a solar cell is a transducer of optical power to electrical power. In this work, we report the structural and optoelectronic properties of sub-wavelength structured silicon films prepared by radio-frequency plasma-enhanced chemical vapor deposition (RF-PECVD) for photovoltaics. Fixed parameters were deposition time of 30 minutes, substrate temperature of 150 °C, hydrogen flow of 50 sccm, power of 30 W and frequency of 13.56 MHz. The varied parameters were silane and pressure at high and low levels. Corning glass and p-type c-Si wafers were used as substrates. Structural characteristics were analyzed by Atomic Force Microscopy, infrared and Raman spectroscopy. Optical properties were estimated by transmittance in the UV-Vis region. By the transmission line method under darkness and illumination conditions, we calculate the photosensitivity for the standard AM1.5. Two groups of samples with similar characteristics resulted, being the flow of silane the key parameter. At 100 sccm of silane flow, films with enhanced photosensitivity were obtained due to the presence of random mesostructures that scatter the light, making the film opaque; the deposition rate was 0.6 nm/s. These films are appropriate for intrinsic layers in p-i-n structures for solar cells. At 10 sccm of silane flow, films that included nanocrystalline regions were obtained; the films exhibited low photosensitivity but high dark conductivity, which is suitable for p or n-type doped layers. 363 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-322 ] Morphological Characteristics of Si:H p-i-n Structures Deposited by PECVD on AZO/Glass Substrates Carlos Alberto Ospina Ocampo ([email protected]) 1 , Andrey Kosarev ([email protected]) 1 1 Departamento de electrónica, INAOE, Luis Enrique Erro # 1, Santa María Tonatzintla, 72840 Heróica Puebla de Zaragoza, Pue. In this paper we present a study of morphological characteristics changes through the various layers comprising a Si:H p-i-n structure, which has been deposited by PECVD on AZO/Corning glass substrates and where the transparent conductive oxide is AZO. AFM measurements were conducted over area of 2 x 2 µm2 to determine morphological characteristics of the substrates, carbon layer, p-layer, as well as intrinsic layer and finally the n-layer. The deposition temperature was set at 160°C and frequency 13.56 MHz. AZO is considered as an inexpensive transparent and conducting material which has been used in industry for flat-panel displays and solar cells. AZO also serves as ohmic contact and as reflective and passivation layer, whereby it is possible to improve the efficiency of photoelectric devices. The behavior of average height, kurtosis and rms roughness parameters is the same layer by layer and skewness behavior is exactly contrary to these three. Average height, kurtosis y rms roughness decrease as the number of layers increases and there is an exception for p-type layer. Skewness increases in value as it grows the number of layers not being seen this in the p-layer. 364 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-333 ] Optical and structure characterization of nand p-type Ga0.86In0.14As0.13Sb0.87 José Saúl Arias-Cerón 3 , Joel Díaz-Reyes ([email protected]) 1 , Julio G. Mendoza-Álvarez 2 , Patricia Rodríguez-Fragoso 2 , José Luis Herrera-Pérez 4 1 Centro de Investigación en Biotecnología Aplicada, Instituto Politécnico Nacional. Ex– Hacienda de San Juan Molino. Km. 1.5. Tepetitla, Tlaxcala. 90700. México. 2 Depto. de Física, CINVESTAV-IPN, Apartado Postal 14-740, México, D.F. 07000. México. 3 Depto. de Ingeniería Eléctrica, SEES, CINVESTAV-IPN, Apartado Postal 14-740, México, D.F. 07000. México. 4 Unidad Profesional Interdisciplinaria en Ingeniería y Tecnologías Avanzadas. Av. Instituto Politécnico Nacional 2580, Gustavo A. Madero, Barrio La Laguna Ticoman. México, D.F. 07340. México Ga0.86In0.14As0.13Sb0.87 quaternary solid solutions lattice-matched to the GaSb (001) substrate were grown by liquid phase epitaxy, which were intentionally doped with Te and Zn in a wide range. Two main vibrational peaks are observed in their Raman spectra over the doping range investigated. The assignment of the observed modes to GaAs-like and (GaSb+InAs)like mixture modes is discussed for each impurity. The comparison of the experimental results with obtained ones by the modified random-element isodisplacement model allows to confirm that the peaks correspond to the vibrational modes associated LO and TO of the binary compounds GaAs and (GaSb+InAs). The photoluminescence for the undoped GaInAsSb shows three narrow exciton-related peaks with narrow full width at half maximum, which is an evidence of the good crystalline quality of the epilayers. The lowtemperature photoluminescence of n- and p-type GaInAsSb were obtained as a function of tellurium and zinc concentrations added to the melt solution. These spectra were interpreted taking into account the nonparabolicity of the conduction (valence) band. Calculations of the peak position and photoluminescence transitions were performed. Both the band filled as well as band tailing effects due to Coulomb interaction of free carriers with ionized impurities and shrinkage due to exchange interaction between free carriers were considered in order to properly account for the observed features of the photoluminescence spectra. It is shown that the band-to-band transition energy can be used to obtain the free carrier concentration in GaInAsSb, for a wide range of dopant concentration. 365 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-336 ] Mg-doped GaN and undoped InN Nanocolumns by HCVD Rafael Garcia Gutierrez ([email protected]) 3 , Godofredo Garcia 2 , Oscar E. Contreras 1 , Ricardo Rangel-Segura 4 1 2 Center of Nanosciences & Nanotechnology, UNAM, Ensenada, B. C. México. Centro de Investigaciones en Dispositivos Semiconductores, BUAP, Puebla, Puebla, México 3 Departamento de Investigación en Física, Universidad de Sonora, Hermosillo,Sonora,Apdo. Postal5-088, C.P. 8300, México 4 División de Estudios de Posgrado, UMSNH, Morelia, Michoacán, México InGaN alloys are ideally suitable for high performance solar cells. Compared with conventional photovoltaic materials such as InGaP and InGaAs, the band gap of InGaN can be tuned from 0.7 to 3.4 eV, covering the full solar spectrum. These alloys exhibit excellent transport properties and show much less deterioration in their optical and electronic properties. In this work we present a low-cost, large-area deposition method, using a halide chemical vapor deposition technique to grow columnar nanostructures of un-doped and doped GaN and InN. These columns show a cathodoluminescence (CL) and photoluminescence (PL) peak at 3.52 eV, in the un-doped samples. That corresponds to the donor bound exciton (DoX). The Mg-doped sample does not show the D°X being the donor acceptor pair (DAP) at ~3.25 eV the dominant emission as it is common in the heavily Mg-doped GaN. Also is possible to observe in this spectrum the blue luminescence related to Mg complex as deep donor. In both CL and PL analysis is possible to observe that the luminescence intensity of the Mg-GaN is superior to the luminescence of the un-doped or unintentional doped GaN. Therefore we concluded that Mg as dopant improves luminescence of GaN as phosphor. 366 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-340 ] Construction of CdSSe/GO multilayer thin films for hybrid solar cells Rafael Valentin Tolentino Hernandez 1 , Rafael Valentin Tolentino Hernandez 3 , Oscar Arón Márquez González 1 , Oscar Arón Márquez González 3 , Javier Armando Barón Miranda 1 , Nereyda Elizabeth Martínez García 1 , Ernesto Silva Galaviz 3 , Sathish Kumar Kamaraj 2 , Fabio Felipe Chalé Lara 1 , Felipe Caballero Briones ([email protected]) 1 , Jesus Guerrero Contreras 1 1 Instituto Politecnico Nacional, Laboratorio de Materiales Fotovoltaicos, CICATA Altamira 2 Universidad Politécnica de Aguascalientes 3 Universidad Tecnológica de Altamira Multilayer films of graphene oxide (GO) and cadmium selenide nanoparticles (CdSSe) with and without molecular functionalization linkers were prepared by sequential electrophoretic deposition and dip-coating techniques for applications in hybrid solar cells. CdSSe nanoparticles were prepared by glycerin mediated precipitation and later functionalized with 1,8-octanedithiol or 6-mercapto-1-hexanol. Electrophoretic deposition of graphene oxide was done from a commercial graphene oxide suspension or from surfactant-assisted mechanically exfoliated graphene onto fluorine-doped tin oxide or aluminium-doped zinc oxide substrates either commercial or prepared by spray pyrolysis. The obtained films were characterized by UV-Vis spectroscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and atomic force microscopy. The photocurrent response was also tested either making a solid device setting the film between two conductive substrates or in front of a sulfide/polysulfide electrolyte. The UV-Vis measurements showed that there is a decrease in the transmittance of the film compared to the transmittance of the substrate without deposition and this decrease varies depending on the molecular linker selected for the functionalization of nanoparticles. The SEM images show different integration of the nanoparticles also in function of the molecular linker. Financed by: SIP 20151074 grant. 367 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-342 ] CdSe/CdS diode by Successive Ionic Layer Absorption and Reaction (SILAR) and Chemical Vapor Deposition (CVD) Iker Rodrigo Chávez-Urbiola ([email protected]) 1 , Yurii Vorobiev 1 , Rafael Ramírez-Bon 1 1 Cinvestav-Qro Research in thin films solar cells and photo-sensors implies a development of different hetero-junctions between p-type and n-type semiconductor; the different growth techniques also are important, so that the same material can have different characteristics depending on the particular technique, like strains, morphology, grain size, porosity, adherence, among others. All these characteristics can affect the junction of two different materials, even in some cases one film can reject a subsequent film due to their characteristics or the growth techniques, so a good compatibility is important between materials and growth techniques. A heterojunction with p-type cadmium selenide having hexagonal crystalline structure is quite suitable for an absorber layer in a solar cell system due to its similarity with cadmium telluride; the cadmium selenide presents a direct band gap (1.7 eV), high absorption coefficient and photosensitive nature. In this work we study the heterojunction formed between CdSe and CdS; also we present an alternative way to synthesize hexagonal CdSe by a combination of techniques (Successive Ionic Layer Absorption and Reaction (SILAR) and Chemical Vapor deposition(CVD)) where each technique has its own advantage: SILAR easily provides films with good adherence, uniform morphology and high thickness control, and with CVD normally gives large grain size and high deposition rate. The CdS layer was obtained by a classical chemical bath deposition (CBD).The films developed were characterized by X-Ray diffraction (XRD), Scanning Electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDX) and the optical reflection spectra recorded in the wave length range 600-800 nm. Electrical properties were found from Hall measurements. The I–V characteristics were obtained using an Agilent semiconductor parameters analyzer. The applied bias voltage varied between −5 V and + 5 V, measurements being taken every 10 mV. The resultant CdSe films are homogenous with good adhesion to the substrate and hexagonal crystalline phase with a band gap of 1.7 eV. It is noteworthy that these films have a large thickness up to 20 micrometers and the grain size 2-3 micrometers with hexagonal shape. All these characteristics of the CdSe films, which are difficult to attain with a single deposition process, are quite suitable for applications in absorption layers in thin film solar cells. The device CdSe/CdS shows a satisfactory behavior as diode at 300K. 368 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-367 ] Stacking Vertical of heterojunctions bulk of organic semiconducting materials and CNS, to build OFETs. Ramón Gómez Aguilar ([email protected]) 2 , Gerardo Ortega Cervantes 1 , Adrian A. Castañeda Galván 2 1 Departamento de Física, ESFM-IPN, U.P.A.L.M. Zacatenco, U.P.A.L.M. Zacatenco, México D.F., C.P. 07738. 2 Departamento de ciencias Básicas. UPIITA-IPN, Av IPN No. 2580, Col. Barrio la Laguna Ticomán, Gustavo A. Madero, México D.F C.P. 07340. Over the years, new technologies have been trying to use inexpensive materials, such as some types of carbon-rich substances, including certain polymers to create organic semiconductors capable of performing the same functions than more expensive technologies based on silicon, at a rate as close as possible to that achieved with the latter.In order to design, build and analyze organic light emitting field effect transistors (OLEFET), Arises the design of the device OLEFET in flexible substrate in different architectures using thin films of the polymer MEH-PPV and MWNT like a bulk heterojunction prepared in solution in aromatic solvents, deposited by different methods, innovating design with the use of a transparent film of carbon nanotubes and graphite flakes as gate elements, source and drain. Emission properties and of current-voltage (I-V), as well as, the combined effects of source-drain voltage and gate voltage were analized to finally build the luminescent flexible device according to predesigned patterns. The OLEFETs show great potential for technological applications in optoelectronics and active-matrix displays. Organic light emitting transistors are constructed based semiconductor MEH-PPV and carbon nanotubes multi-walled (MWCNTs) and gate and / or source-drain electrodes deposited on a flexible substrate film of PET. The devices were electrically and optically characterized. MWCNTs were synthesized by microwave irradiation technique. A mixture of graphite powder and bimetallic catalyst (CoMo). CNTs were deposited on a flexible substrate as a thin film, to be used as gate. The architecture used was vertical, ITO / PEDOT: PSS / MEH-PPV:CNT-CoMo/ Gain / PMMA / CNT-CoMo. One of the important conclusions is that in these transistors, we can see in the source-drain current a linear behavior below 300mV and a regimen of saturation below 1 Volt, results that allow modular current at low gate voltages. The second is the importance of the sensitivity to ambient light, which makes it a candidate to be an opto-transistor competent. Finally, the response to the presence of O2 among other environmental gases allow us to think in a broader application as gas detectors transistors. All these phenomena are made present in its response I-V characteristic of our devices. 369 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-376 ] Amorphous iron oxide/sulfide (a-FeO/S) thin films via chemical bath deposition: characteristics and properties D. A. Mazón Montijo ([email protected]) 1 , M. T. S. Nair 1 , P. K. Nair 1 1 Instituto de Energías Renovables - UNAM Iron oxide is known for its wide variety of phases, each of which with its chemical and physical properties that are functions of their crystalline structure and chemical composition. The versatility of iron oxide includes the interest in its amorphous phase. The amorphous iron oxide (a-FeO) films are especially used as precursor-films for other iron oxide phases and even for iron sulfide or disulfide films. Moreover, they have also been studied for their properties and functionality in photoelectrochemical devices. To improve the performance of devices based in these materials, research works have been done to modify their electronic, optical, electrical and charge carrier transport properties through adding cationic and anionic doping agents such as Al, Ni, Ti, Sn, S and Se. In this work, we present the preparation and characterization of chemical bath deposited iron oxide/sulfide (a-FeO/S) thin films. The films were deposited on glass substrate at 40 °C at different deposition time. The chemical bath contained ferric nitrate, sodium thiosulfate, hydrochloric acid and triethanolamine at pH ~ 7– 8. Uniform thin films deposited on both sides of the glass substrate appear orange-yellow in daylight and with amorphous structure. The films thickness presented a typical tendency to increase from 120 to 315 nm with the increase of deposition duration from 0.5 to 2.5 h. The work will deal with show the details of the chemical composition, morphology, optical and electrical properties of the films. All features and properties presented by the a-FeO/S films can be exploited for their use in photovoltaic and/or photoelectrochemical devices. 370 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-377 ] Photoluminescence spectroscopy study of ntype GaSb passivated by acid Mercaptosuccinic Delia María Hurtado-Castañeda ([email protected]) 4 , Fabiola Vázquez-Hernández 1 , José Saúl Arias-Cerón 2 , José Luis Herrera-Pérez 3 , Daladier Alonso Granada-Ramírez 5 , Juan Pedro Luna-Arias 1 , Julio Gregorio Mendoza-Álvarez 5 1 Department of Cell Biology, CINVESTAV-IPN. México, D. F. 07000, México Department of Electrical Engineering-SEES, CINVESTAV-IPN. México, D. F. 07000, México 3 Instituto Politécnico Nacional-UPIITA, Av. IPN 2580, Col. La Laguna Ticomán, México DF 07340 4 National Institute of Astrophysics, Optics and Electronics, Luis Enrique Erro # 1, Santa María Tonantzintla, Puebla-México, 72840 5 Physics Department, Cinvestav-IPN, A.P. 14-740, México DF 07000 2 In this work, we have studied the influence of mercaptosuccinic acid (MSA) passivation on the surface of n-type (100) GaSb single crystals doped with Te at concentrations of around 5x1017 cm-3, through the low temperature photoluminescence (PL) spectroscopy. After a cleaning process of the GaSb substrates to remove the oxides layers, the samples were treated at different times using an aqueous solution of MSA. By measuring the PL intensity change as a function of the aqueous MSA treatment times we can optimize the MSA passivation time on the surface of the GaSb single crystals, measuring the efficiency of the aqueous MSA passivation, through the measurement of the PL intensity for the different passivation times. The effect of different treatment times of the GaSb surfaces on the surface recombination velocity was investigated using low temperature PL spectroscopy. Finally, we described the variation as a function of the passivation time of the relative contribution to the PL intensity of the different transitions involved in the passivation process. 371 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-379 ] Effect of deposition temperature on the formation of the SiO2/ZnO/SiO2 heterostructure by reactive RF sputtering.* R. Escobedo-Alcaraz 1 , C. Atzin-Mondragon 1 , A.P. Chavelas-González 4 , A. Hernández-Hernández 2 , L.A. Hernández-Hernández 3 , A.R. GarcíaSotelo 1 , M. Meléndez-Lira ([email protected]) 1 1 Departamento de Física, CINVESTAV-IPN, , Apdo. Postal 14-740, México, DF 07000, México 2 Escuela Superior de Apan, Universidad Autónoma del Estado de Hidalgo, Calle Ejido de Chimalpa Tlalayote s/n Colonia Chimalpa, Apan Hidalgo, México. 3 Escuela Superior de Física y Matemáticas del Instituto Politécnico Nacional, Edificio 9 U.P. Adolfo López Mateos, Col. San Pedro Zacatenco, C.P. 07730 México DF, México 4 Universidad Politécnica del Valle de México, Av. Mexiquense s/n, esquina Av. Universidad Politécnica, Col. Villa Esmeralda, C.P. 54910, Tultitlán, Estado de México. The roughness associated with the sputtering deposition process has been employed to explore the possibility to produce ZnO nanoparticles embedded within a silicon oxide matrix on soda-lime glass and p-silicon substrates. Silicon dioxide and metallic Zn films were deposited employing silicon and zinc targets. An oxygen rich working plasma was employed. A sequential deposition of SiO2/Zn/SiO2 films were deposited ; SiO2 layer was produced at 400 °C while deposition temperature of Zn layer was changed between 100 and 500 °C. We present results of the chemical, structural and electronic properties. Results indicated the successful production of ZnO with properties depending on temperature. *: Partially funded by CONACyT-Mexico 372 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-386 ] Genetic algoritms for solve reflectance spectrum for porous silicion multilayers Cristian Felipe Ramírez Gutiérrez ([email protected]) 1 , Mario Enrique Rodríguez García ([email protected]) 1 1 Centro de Física Aplicada y Tecnología Avanzada, Universidad Nacional Autónoma de Mexico Campus Juriquilla, Qro., Mexico The porous silicon (PS) multilayers are a heterostructure made through electrochemical etch. The electrochemical etch route for doing PS films is very sensible to different parameters like: HF/surfactant ratio, electrolyte temperature, current density, resistivity among other, and it is usually characterized by UV-VIS reflectance. However, neither electrochemical process or UV-VIS spectrum provide direct information about the thickness and porosity of the films, for these reason we develop an algorithm based in genetic algorithms (GA) to fitting the UV-VIS. The GA can fit the UV-VIS spectrum in the range of 1100 to 200 nm for a heterostructure composed by PS film and Si substrate using as parameters the following chromosome: where p is the porosity, d the thickness, and and are the RMS roughness of the interfaces air/PS and PS/SI respectively, and using like penalty function the optical response stimulated by characteristic matrix method and any effective medium theory that have been the best fit. In this work we show the simulation and fit of optical response for four differents films of PS and we compared the results with SEM. 373 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-387 ] Defect photoluminescence in ZnS films Berenice Y. Valles Pérez 1 , Aarón Hernán Barajas Aguilar 1 , Francisco Rodríguez Melgarejo 1 , Martín Adelaido Hernández Landaverde 1 , Gabriel López Calzada 1 , Sergio Joaquín Jiménez Sandoval 1 1 Centro de Investigación y de Estudios Avanzados del IPN, Unidad Querétaro Zinc Sulfide (ZnS) is a well-known luminescent semiconductor material, having prominent and promising applications in displays, sensors, blue-light emission devices and as window layer in thin-film solar cells [1-3]. Some of its advantages include low cost and non-toxicity. It exhibits wide optical transparency from the ultraviolet to the infrared. This optical transparency combined with its chemical and thermal stability makes ZnS a strong candidate for its use as window layer in hetero-junction photovoltaic cells [1]. Structural defects, especially vacancies, exist commonly in ZnS crystals due to variations in temperature and pressure during the crystallization process. The defect density influences the electronic properties and, therefore, affects the ZnS physical and chemical properties [4]. In the present work we report the growth by RF sputtering of ZnS thin films as well as their luminescent properties at room temperature and at 80 K. Substrates were made of Corning glass and kept at various temperatures during growth (RT, 200 and 300 °C). The deposition time, RF power and total pressure were kept constant during depositions. To promote the formation of zinc or sulfur vacancies the targets were made from different mixtures of ZnS and adding controlled quantities of Zn or S powders. The structural properties were characterized by Xray diffraction. The optical properties were determined by UV-VIS and photoluminescence spectroscopies. [1] H.M.M.N. Hennayaka,Ho Seong Lee, Thin Solid Films 548 (2013) 86-90. [2] V.L. Gayou, B. Salazar-Hernandez, M.E. Constantino, E. Rosendo Andrés, T. Díaz.Vacumm 84 (2010) 1191-1194. [3] Rengang Zang, Baoyi Wang, Long Wei. Vacumm 82(2008) 1208-1211. [4] Jinhuan Yao, Yanwei Li, Ning Li, Shiru Le. Physica B 407 (2012) 3888-3892. 374 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-397 ] Structural, optical and electrical characterization of Li doped PbS thin films. Melissa Chavez Portillo ([email protected]) 1 , Mauricio Pacio Castillo ([email protected]) 1 , Hector Juarez Santiesteban 1 , Oscar Portillo Moreno 2 , Xavier Matthew 3 1 2 CIDS BUAP Ciencias Quimicas BUAP 3 IER, UNAM Lithium (Li+) doped Lead sulfide (PbS) thin films were prepared chemical bath method. The concentration of Lithium in the precursor solution of Lead Sulphide was varied from 3mls to 6mls. The structural properties of as deposited films were characterized by X-ray diffraction. XRD patterns indicated the presence of cubic phase PbS with preferential orientation along (111) plane. Optical absorbance in visible region of the film increases with dopant concentration. The optical measurements reveal that the PbS:Li thin films possess direct band gap and the band gap energy increases with an increase of Li+ concentration. Thin films were found to be 1.8, 2 and 2.1 eV respectively. The dc conductivities of PbS and PbS:Li thin films are measured in temperature range 10–40 K. It is observed that the thermal conductivity increases at with an increase of Li content in PbS system. The experimental data suggests that the conduction is due to thermally assisted tunneling of the charge carriers in the localized states near the band edges. The activation energy and optical band gap are found to increasae with increasing Li concentration 375 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-398 ] Deposit and characterization of metal oxides on silicon porous for use in gas sensor Raul Juárez nahuatlato ([email protected]) 1 , Godofredo García 3 , Mauricio Pacio 3 , Crisoforo Moroles 3 , Tomas Díaz 3 , Enrique Rosendo 3 , Valentín López 2 , Gabriela Nieto 3 1 2 BUAP CIBA-IPN 3 ICUAP ZnO particles supported on a porous silicon structure and used as ethanol sensor is presented in this work. ZnO particles obtained in a colloidal solution were mixed with the traditional ethanoic solution of hydrofluoric acid (1:2:2) to obtain porous silicon. Another colloidal solution mixed with formaldehyde and hydrofluoric acid was used too (1:2:2). XRD, FTIR, and UV-vis spectroscopy were used to corroborate the presence of the ZnO particles in the porous silicon matrix. Gravimetry measures were obtained to control the porosity and thickness of the porous silicon with ZnO particles layer, in both solutions. Porous silicon with ZnO particles sensors were obtained in normal and free standing layers, showing a better response that sensors obtained without ZnO [1][2][3]. It is concluded that the ZnO particles growth on the porous silicon surface enhanced the oxide-reduction mechanisms giving place to an increase in the conduction response of the sensors in presence of ethanol. [1]. O. Bisi, S. Ossicini and L. Pavesi, Surf. Sci. Rep. 38,1, 2000 [2] D. Bellet, G. Dolino, Thin Solid Films 276 (1996) 1. [3] Dazhi Sun, Minhao Wong, Luyi Sun, Yuntao Li, Nobuo Miyatake, Hung-Jue Sue, “Purification and stabilization of colloidal ZnO nanoparticles in methanol” J Sol-Gel Sci Technol (2007) 43:237–243. 376 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-403 ] Solvothermal synthesis of the ternary compound ZnHgS E. A González de la Torre 1 , A. Pérez-Centeno 1 , Arturo Chávez-Chávez 1 , José Quiñones-Galván 1 , Miguel Ángel Santana-Aranda ([email protected]) 1 1 Departamento de Física, CUCEI, Universidad de Guadalajara The sulfide ternary compound ZnHgS is a promising material for optoelectronics applications which has been barely studied because of the difficulties involved on its synthesis; or even more, its thin film deposition. Quite few reports involving this compound, that could be useful in a wide range of the electromagnetic spectrum (from 0.5 to 3.7 eV), have been published. Back in 1960, Kremheller et al. (J. Electrochem. Soc. 107, 12) reported a hydrothermal process to obtain some concentration values of the ternary, starting with mixtures of the binary compounds, ZnS and HgS. In this work, we propose a solvothermal process in ethanol-water mixtures, by mixing the binary compounds, for comparison, and different combinations of reactant sources for zinc, mercury and sulfur. The crystalline structure of the samples was characterized by X-ray diffraction and Raman; the morphology with scanning electron microscopy images; and the band gap was estimated from UV-Vis measurements. Acknowledgements: Authors want to thank the technical support of Sergio Oliva. This work was partially supported by CONACyT (grant CB2010-156773) and U. de G. (programs proSNI and PROINPEP). 377 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-406 ] A study of Ge nanocrystals embedded within a SiO2 matrix produced by RF sputtering.* A. García-Sotelo 1 , E. Campos 1 , S. Gallardo-Hernandez 1 , A. HernándezHernández 2 , J.L. Enríquez-Carrejo 3 , P.G. Mani-Gonzalez 3 , J.R. FariasMancilla 3 , M. Melendez-Lira ([email protected]) 1 1 Departamento de Física, CINVESTAV-IPN, Apdo. Postal 14-740, México, DF 07000, México 2 Escuela Superior de Apan, Universidad Autónoma del Estado de Hidalgo, Calle Ejido de Chimalpa Tlalayote S/N Col. Chimalpa, Apan, Hidalgo. México 3 Universidad Autonoma de Ciudad Juarez- IIT, Departamento de Física y Matemáticas. Av del Charro 450 norte. Cd. Juárez, Chihuahua. México. CP 32310. The characteristics of germanium, mainly its compatibility with silicon technology and the sensitivity of its band structure to confinement confer a high attractive to the synthesis of germanium nanostructures. The samples were prepared on p-type Si (1 1 1) substrates by reactive sputtering. Structural characterization was carried out by grazing angle X-ray diffraction. Surface roughness was quantified by atomic force microscopy and correlated with micro Raman spectroscopy imaging. Micro-Raman mapping allow to obtain the Ge nanocrystals distribution. XPS indicates that there is a transition layer with a gradual composition around Ge nanocrystals. SIMS results are well correlated with the Ge depth distribution observed by micro-Raman imaging. IvsV and spectral response results are correlated with the size and spatial distribution of Ge nanocrystals. TEM micrographies indicate the presence of unstable phases of Ge. *: Partially funded by CONACyT-Mexico 378 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-408 ] SIMS and HRXRD study of the deviation from the Vegard’s law of GaNAs layers grown by PAMBE José Angel Espinoza Figueroa ([email protected]) 1 , Estebán Cruz Hernández ([email protected]) 1 , Salvador Gallardo Hernández 2 , Eliseo García Ramírez 1 , Miguel Angel Vidal Borbolla 1 , Máximo López López 2 , Víctor Hugo Méndez García 1 1 CIACyT, Universidad Autónoma de San Luis Potosí 2 Departamento de Física, CINVESTAV The incorporation of Nitrogen (N) in GaAs is a very important topic in the recent years for the realization of the quaternary material that includes GaNAs such as GaNAsSb, InGaNAs and GaNAsP. These materials has an remarkable relevance for the development of new optoelectronic devices due to the property of Nitrogen (N) of decreasing the bandgap of GaAs, allowing the so-called bandgap engineering, and for relieving the lattice strain when coupled to GaN. For GaNAs layers diverse parameters are involved to achieve an optimal growth like nitrogen flux pressure, Ga/As ratio, growth rate, N RF power, doping and growth temperature. Each one of these parameters can modify the characteristics of the GaNAs layers in such a way that the Vegard Law is not longer followed by this material. In this work, GaNAs films were grown by Molecular Beam Epitaxy (MBE) using GaAs (100) as substrate. After desorption at 580°C, a 500 nm buffer layer of GaAs was grown, in order to obtain a flat surface, then 100 nm-thick of GaNxAs1-x layers were grown at temperatures ranging from 400 to 600 °C. The crystal quality of the films was evaluated by High Resolution X-Ray Diffraction (HRXRD) and for the measurement of the N incorporated Secondary Ion Mass Spectroscopy (SIMS) was performed. The results obtained by HRXRD were analyzing with Vegard’s Law, by performing simulations based on the dynamical theory. We found that the concentrations vary from 1.16 to 3.1% of N incorporated into the GaAs matrix. But when we compare the SIMS and HRXRD results, we found that for the samples grown at low temperatures (<500 °C) the concentrations are higher than that obtained by the HRXRD simulations. Conversely, the samples grown at higher temperatures the N concentrations are almost the same as obtained from both techniques. This deviation from the Vegard’s Law could be caused by the very nature of N. When the Nitrogen is incorporated into the GaAs lattice, it does in different ways: the N not only occupy sites of Arsenic (As) as expected, but can also occupy sites of Gallium (Ga) and form different bonds like Ga-N, As-N and even N-N in both the lattice or in interstitial sites. We explain the discrepancy between the SIMS and HRXRD results as a consequence of the N incorporation in interstitial sites. Acknowledgments: The author acknowledges the financial support of CONACYT, CeMIESOL 22, FRC-UASLP, INFR-2015-01: 255489, PNCPN2014-01: 248071 and CB: 168761. 379 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-416 ] Silicon-on-insulator Self-Switching Diode analyzed by TCAD-simulations Irving Eduardo Cortes Mestizo ([email protected]) 1 , Joel Briones 2 , Edgar Briones 1 , Víctor Hugo Méndez García ([email protected]) 1 1 CIACyT, Universidad Autónoma de San Luis Potosí, San Luis Potosí, 78210 SLP, México 2 Instituto de Estudios Superiores de Occidente, Guadalajara, 45604 GDL, México The manipulation of surface states, surfaces charge and depletion zone allows to develop a surface-states engineering such as the Self-switching diode (SSD) device developed by A. M. Song [1]. In that device a nano-channel between two L-shape insulating grooves is fabricated by electron beam lithography. The depletion zone caused by surface states in the groves, lets the current flux only in one direction. The SSD exhibits the advantage of high frequency cut-off and simplicity of fabrication. Even when the SSD has been extensively studied in III-V heterostructures for THz applications, the working principle of the device permits the use of cheap and widely applied bulk-materials like silicon. In this work the DC and AC performance of Silicon-on-insulator (SOI)-based SSD are evaluated by TCAD software. Simulation indicates that the geometrical shape and size of the grooves have a strong effect on the performance of the device. The viability of modifying the turn-on voltage in the diode-like current-voltage characteristic from ~0 to 1 V by controlling the surface density and/or the SSD geometry is demonstrated in the DC-injection mode, where the relationship between channel width and surface-charge is the key issue. The AC performance is determined by the vertical grooves widths, a large width propitiates higher frequency cutoffs. Transient simulations verify the viability of use the SSD as a half- and full-wave rectifier by the correct array of SSDs. Three-dimensional simulation in conjunction with a self-heating model are used in order to define the appropriate silicon layer thickness of the devices that improve the current-voltage response and reduce the typical thermal issues of SOI technology. This numerical study indicates that SOI technology can be applied to the SSD concept and the way to determine the best geometry for a desire application improving the DC and AC response. [1] A. M. Song et al. Appl. Phys. Lett. 83, 1881 (2003). The author acknowledges the financial support of CONACYT, CeMIE-SOL 22, FRCUASLP, INFR-2015-01: 255489 and PNCPN2014-01: 248071. 380 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-446 ] Incorporation of Ag nanoparticles in solvothermal-assisted spin coated TiO2 layers E. A. González-De-La-Torre 1 , K. Y. Sillas-Montaño 1 , J. G. GuiñonesGalván 1 , G. Gómez-Rosas 1 , M. A. Santana-Aranda 1 , A. Pérez-Centeno ([email protected]) 1 1 Departamento de Física, Centro Universitario de Ciencias Exactas e Ingeniería – Universidad de Guadalajara (CUCEI-UDG). Guadalajara, Jal., México TiO2 is a semiconductor material with extraordinary optical properties which are dependent on its size and crystalline structure. It is the reference material for photocatalytic activity, furthermore, it is a suitable material for solar cell applications. In this work, we analyze the structural, optical and morphological properties of TiO2 films deposited by spin-coating on glass substrates, using titanium n-propoxide diluted with isopropanol. In order to crystalize TiO2, we compared samples solvothermally pre-treated with conventional calcination process. We analyzed the quality of the film, in particular the surface coverage. We also compared the influence of time and synthesis temperature. Finally, the incorporation of Ag nanoparticles, produced by laser ablation in water, within the TiO2 layers was explored. XRD and Raman spectroscopy were used to analyze the crystalline structure. The optical and morphological properties were studied through UV-Vis spectroscopy and SEM images, respectively. Authors want to thank the technical support of Sergio Oliva. This work was partially supported by CONACyT (grant CB2010-156773) and U. de G. (programs pro-SNI and PROINPEP). 381 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-480 ] Electrochemical properties of TiOx thin films deposited on different metal substrates. E. Valaguez ([email protected]) 4 , M. Zapata - Torres 1 , E. Hernández Rodríguez 2 , J.L. Fernández Muñoz 1 , O. Calzadilla Amaya 3 1 CICATA-IPN, Unidad Legaria, Legaria 694 C.P. 11500 . México D.F. Departamento de Física Aplicada, CINVESTAV-IPN, Unidad Mérida, Km. 6 Antigua carretera a progreso. C.P. 97310, Mérida, Yucatan, México. 3 Facultad de Física. Universidad de La Habana. San Lázaro y L. C.P. 10400. La Habana Cuba 4 UPIITA-IPN, Av. Instituto Politécnico Nacional 2580. C.P. 07340. México D.F. 2 Titanium Dioxide is a promising photocatalyst for its strong oxidation potential and its moderate potential reduction due to the generation of electron - hole pairs in the valence band (VB) and conduction (BC). The excited electrons in the BC reduce oxygen in super oxide radical, and holes in the BV oxidize water molecules into hydroxide radicals. These radicals are potent intermediates in the decomposition of organic molecules. In addition, the TiO2 is physically and chemically stable and nontoxic therefore has a variety of applications such as self-cleaning surfaces, antimicrobial and environmental purification. In this work TiO2 thin films have been deposited on different metal substrates, using reactive Rf sputtering technique. The structural and chemical bonding characteristics were analyzed by X- ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). UV-Vis diffuse reflectance spectroscopy was employed to determine the band gap energy. The electrochemical properties of films on different metal substrates were obtained using the electrochemical impedance spectroscopy, mott schottky and cyclic voltammetry. The results shown a strong dependence of the metal used as substrate with the electrochemical properties of the films. This work was supported by SEP CONACYT (project 153245) and SIP-IPN (project 20150173) 382 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-494 ] Optical and structural properties in ZnO nanostructures due to CTAB surfactant concentrations. Edith bravo González 2 , Aarón Israel Diaz Cano 2 , Efraín rubio rosas 1 , Yosemik Arjuna León Nataret ([email protected]) 2 1 2 Benemerita Universidad Autonoma de Puebla, San Manuel, 72570, Mexico Instituto Politecnico Nacional, UPIITA, Gustavo A. Madero, 07340, Mexico Zinc Oxide (ZnO) nanostructures were synthesized by the Microwave Assisted Hydrothermal method (MAH). The precursors used were Zn(CH3COO)2∙2H2O dissolved in aqueous solution of NaOH and a concentration of 1M and stirred for 10 minutes. Were prepared 4 solutions with 50 mL incorporating slowly 1 mL, 2 mL and 3 mL CTAB (Cetyltrimethylammonium bromide) surfactant. One sample is not use surfactant to compare finally results. Was used a digestion oven in two phases, first 10 minutes, 900W and 150°C, and second 30 min, 700W and 150°C. The samples were cooled 20 min for his subsequent extraction and centrifuged at 3600 rpm for 25 min. Finally were washed with deionized water and dried at 60°C in air. Were used Photoluminescence (PL), UV-Vis, Raman scattering, XRay Diffraction (XRD) and Scanning Electron Microscopy (SEM) characterization for the comparative study of ZnO nanostructures. Four PL bands appear with the PL peaks at 1.54, 2.08, 2.81 and 3.08 eV due to morphology changes in function of CTAB surfactant concentration. UV-Vis studies exhibit an increase of band gap (4.65 – 5.0 eV) due to the enlargement in the size and density of ZnO Nanocrystals (NCs). RAMAN studies shown bands centered in in 438 cm-1, 378 cm-1, 327 cm-1, 522 cm-1, 1075 cm-1, 150 cm-1 and 165 cm-1, shows ZnO phases corresponding to the main phonons signal in ZnO like-flower morphology (3E2H-E2L), degrees of order-disorder network ZnO, degrees corresponding to the contribution of energy E1 and harmonics tones of the combinations bands. It is shown that the Raman intensity for all peaks in ZnO NCs is high twofold in comparison with those in ZnO with low concentration of surfactant. XRD studies have shown that the thermal annealing stimulates the ZnO oxidation and crystallization with the creation of wurtzite crystal lattice (JCPDS 36-1451) and SEM studies show different morphologies (spherical, wires, like-flowers & amorphous) with NCs size of 29.4 nm (diameter´s wires) and 363.6 nm (flowers petal). 383 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-504 ] Synthesis and characterization of QDs ZnO by colloidal method Yosemik Arjuna León Nataret 2 , Aarón Israel Diaz Cano 2 , Efraín Rubio Rosas 1 , Edith Bravo González ([email protected]) 2 1 2 Benemerita Universidad Autonoma de Puebla, San Manuel, 72570, Mexico Instituto Politecnico Nacional, UPIITA, Gustavo A. Madero, 07340, Mexico This work describes a simple process to obtain Zinc Oxide (ZnO) nanocrystals with low dimension. The electronic, structural and compositional characteristics were discussed. Quantum Dots Zinc Oxide (QDs ZnO) were synthetized by colloidal method using 0.05M Zn(CH3COO)2∙2H2O in 50 ml Absolute Ethanol solution. It was stirred by 2 hrs at 700 rpm and 80°C. A second absolute ethanol solution was prepared as previous solution at 0.1 M LiOH∙H2O, this solutions was added to the first at the same time that it stirred at 700 rpm, 80°C for 2 hrs. The pressure increasing was controlled to sealing the flask perfectly to conserve temperature and pressure constants. Finally it was washed in Ethanol, centrifuged at 4000 rpm and dried for 3 hrs at 80°C. The characterization showed a hexagonal phase (wutzite crystalline structure) according to JCPDS 36-1451. The crystal sizes were analyzed using Scherrer equation in the (100), (002), (101) family planes using XRD information (711 nm). The EDS microanalysis identified the atomic relation in function of %W (weight) and it has 83.16 % and 16.84 % for Zn and O respectively. It confirmed the results obtained by XRD technic. TEM measured particles with semi-spherical morphology around 7.3 nm, witch confirmed the Nanocrystal (NC) sizes obtained in XRD processing analysis. FTIR spectroscopy identified different vibrational modes in bands centered in 542 cm-1, 678 cm-1, 828 cm-1, 1592 cm-1 and 3326cm-1 to corresponds to stretching frequencies for pure ZnO (NC), the charge in the microstructural features into ZnO lattice, H-O-H assigned to small amount H2O in the QDs ZnO NCs and O-H vibrational frequencies. PL spectroscopy showed the emission wavelength around 590 nm to correspond to red emission, the process to generate this emission is generally considered as originating intrinsic defects of nanocrystals such as oxygen vacancies. 384 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-510 ] Structural properties of GaN films grown on SiC/Si(111) Mario Cervantes Contreras ([email protected]) 1 1 Departamento de Ciencias Básicas, Unidad Profesional Interdisciplinaria de Biotecnología - Instituto Politécnico Nacional. Av. Acueducto s/ n Col. Barrio la Laguna Ticoman, C. P. 07340 México city, México Although some early studies of GaN deposition on SiC employed lowtemperature buffer layers for nucleation of the GaN (in analogy with nucleation on sapphire), more recent workers have deposited the GaN directly on a suitably prepared SiC surface. In this work we studied the different nucleation processes on (111) oriented Si substrates. We prepared GaN films over SiC/Si(111) using different growth conditions. The GaN layers were grown in a conventional molecular beam epitaxy (MBE) system with a RF activated nitrogen plasma source (P = 400 W and f = 2 sccm). The GaN/SiC(Si(111) structural properties were evaluated by X – ray diffraction Raman spectroscopy and transmission electron microscopy (TEM). The surface morphology of the films was investigated by atomic force microscopy (AFM). We found that even when there is no intentional nitridation, the higher reactivity between Si and N leads to the formation of an amorphous SiN layer at the interface. In spite of the presence of the amorphous SiN layer, the GaN films grew epitaxially with the hexagonal phase. In order to avoid the formation of the amorphous SiN layer we employed a SiC buffer layer at the interface (Figure 1). In this way we tried to reduce the reactivity between Si and N. The results obtained by different characterizations techniques showed that the SiN layer formation was avoided, but the obtained films presented the hexagonal phase. 385 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-519 ] Analysis of AlGaAs:Si/GaAs heterostructures grown as a function of the arsenic beam equivalent pressure. L.I. Espinosa Vega ([email protected]) 1 , S. Shimomura 2 , E. Cruz Hernández 1 , D. Vázquez Cortes 2 , A.G. Rodríguez 1 , J.J Ortega 3 , Víctor Hugo Méndez ([email protected]) 1 1 Coordinación para la Innovación y la Aplicación de la Ciencia y la Tecnología (CIACYT), Universidad Autónoma de San Luis Potosí, Universidad Autónoma de San Luis Potosí, Álvaro Obregón 64, San Luis Potosí, S.L.P., 78000, México 2 Graduate School of Science and Engineering, Ehime University, 3 Bukyo-cho, Matsuyama, Ehime 790-8577, Japan. 3 UAF-UAZ, Av. Preparatoria S/N, campus II, Col. Hidráulica, C.P. 98060, Zac., México. One of the most promissory and intriguing nanostructures though which exciting fundamental physics has arose and that have numerous applications in advanced devices are the quantum wires (QWRs), where the charge carries are confined to freely move only along one spatial direction. The motivation for studying the growth on (631) substrates arises from the fact that under appropriated growth conditions uniform nanoscale step arrays can be synthesized which for instance can be used as nanotemplates for QWRs self- assembly. In this work, we present the analysis AlGaAs:Si/GaAs heterostructures grown on GaAs (631) and (100) sustrates as a function of the As-cell beam equivalent pressure studied by high resolution X-ray Diffraction (HRXRD) and Raman spectroscopy. Raman spectroscopy in back-scattering geometry has been used for the characterization. It is observed for the AlAslike modes of the AlGaAs (631) films, which the ratio between transverse optical phonon (TO) and longitudinal phonons (LO) increases with PAs, while for the (100) plane the ratio decreases. These observations are related with HRXRD characterization of the films: high crystalline quality for films grown on (100) as compared to the films grown on the (631) crystallographic orientation was obtained. Additionally, by HRXRD it was found PAsdependent Al concentration in the AlGaAs alloys related to the Ga and Al competition for III sites that frequently occurs in high index substrates. 386 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-540 ] Synthesis and characterization of p-doped GaAs films grown by Molecular Beam Epitaxy José Alberto Piedra-Lorenzana ([email protected]) 1 , Yenny Lucero Casallas-Moreno 1 , Dagoberto Cardona 1 , Salvador GallardoHernández 1 , Gilberto Gamaliel Díaz-Monroy 1 , Carlos Alberto Hernández-Gutiérrez 1 , Máximo López-López 1 1 Departamento de Física, CINVESTAV During the past last decades, considerable research has been devoted to the physical properties and the device behavior of III-V compounds semiconductors. The Development of p-type doping techniques is needed for the design of multilayer devices. In this work, we present the growth of p-doped GaAs films using Molecular Beam Epitaxy (MBE), the synthesized films were (p-doped with Magnesium (Mg) and Beryllium (Be)). With the aim of investigate the surface morphology and the hole concentration, the films were grown by varying the Mg beam flux equivalent pressure (BEPMg) in the range of 1.5x10-9 to 3x10-8 Torr and the growth temperature Tg in the range of 530°C to 595°C. FESEM pictures show a clear difference between the Be-doped GaAs layers and the Mgdoped GaAs layers. The Be-doped GaAs layers shown characteristical GaAs defects, the density of defects decreases as the BEPBe increase, Atomic Force Microscopy (AFM) shows higher roughness of Mg-doped GaAs than Be-doped GaAs. We found that for high flux of Magnesium (BEPMg of 2.95x10-8 cm-3), the Magnesium segregates to the surface and starts the formation of Magnesium Arsenide (MgAs) according to Secondary ion mass spectrometry (SIMS) and X-ray diffraction (XRD). The measurement of the hole concentration was made using hall effect at room temperature, the mobility for both dopants increase as the carrier concentration decrease, the highest mobility of 128.249cm2V-1s-1 and 194cm2V-1s-1 corresponds to 3.37x1018cm-3 and 1.78x1018 cm-3 for Bedoped GaAs and Mg-doped GaAs respectively. 387 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-544 ] Fabrication of InGaAs semiconductor lasers for applications in technologies of the information José Vulfrano González Fernández ([email protected]) 3 , Ismael Lara Velázquez ([email protected]) 1 , Ramón Díaz de León Zapata 2 1 2Instituto Tecnológico Nacional de México ITSLP, San Luís Potosí, SLP, 78437, México 2Instituto Tecnológico Nacional de México ITSLP, San Luís Potosí, SLP,78437, México 3 Instituto de Investigación en Comunicación Óptica, Universidad Autónoma de San Luis Potosí San Luís Potosí, SLP, 78210, México 2 Abstract This work presents the fabrication of optic and electronic confinement semiconductor laser diodes with InGaAs/GaAs quantum dots matrix in the active area grown by self-assembly technique in the Molecular Beam Epitaxy system and their morphological and optical characterization. It seeks to tone the spectrum of photo-emission of the above mentioned devices around the windows lower electromagnetic absorption of optical fiber telecommunications systems. 388 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-548 ] Cleaning of GaN Surface by Chemical Method D. A. Flores-Cordero ([email protected]) 2 , Y. L. CasallasMoreno 3 , C. A. Hernández-Gutiérrez 3 , D. Cardona-Ramirez 3 , S. Gallardo-Hernández 1 , M. López- López 3 1 Electric Engineering Department, Centro de Investigación y Estudios Avanzados del IPN, Apartado Postal 14-740, 07360 México, D. F., México. 2 Escuela Superior de Ingeniería Química e Industrias Extractivas, ESIQIE, Apartado postal. 07738. México D.F. 3 Physics Department, Centro de Investigación y Estudios Avanzados del IPN, Apartado Postal 14-740, 07360 México, D.F., México. Gallium nitride (GaN) is a semiconductor with a band gap of 3.4 eV of great technological interest, and is very important for manufacturing optoelectronic devices such as LEDs, Laser diodes, photodetectors. In order to improve efficiency of these devices, it is indispensable the fabrication good ohmic contacts on GaN layers. In this work we present two methods of chemical cleaning for GaN which removes contaminants such as a carbon and oxides that hinder the realization of good ohmic contacts. The first method is to treat the surface of GaN with a piranha solution (HCL:HNO3:H2O) in proportion (1:2:1). The second method is to treat the surface with an acid solution (H2SO4:H2O2:H2O) in proportion (3:1:1) and subsequently with an alkaline solution (NH4O:H2O2:H2O) in proportion (1:1:3). These chemical methods in addition to reducing surface impurities such as oxides, do not alter the surface morphology of GaN samples. The chemically cleaned samples by these two methods were analyzed by XPS (X-ray Photoelectron Spectroscopy) and transmission line. 389 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-550 ] Device performance for InGaAsSb infrared photodetector grown by liquid phase epitaxy José Luis Herrera-Pérez ([email protected]) 2 , Delia María HurtadoCastañeda ([email protected]) 3 , José Saúl Arias-Cerón 1 , Patricia Rodriguez-Fragoso 4 , Julio Gregorio Mendoza-Álvarez 4 1 Department of Electrical Engineering-SEES, CINVESTAV-IPN. México, D. F. 07000, México 2 Instituto Politécnico Nacional-UPIITA, Av. IPN 2580, Col. La Laguna Ticomán, México DF 07340 3 National Institute of Astrophysics, Optics and Electronics, Luis Enrique Erro # 1, Santa María Tonantzintla, Puebla-México 72840 4 Physics Department, Cinvestav-IPN, A.P. 14-740, México DF 07000 We report on the characterization of the resistance area product at zero bias, R0A=dJ/dV|V=0, for the InGaAsSb/GaSb photodiode grown by liquid phase epitaxy. The calculated R0A values were 8.11 ohms-cm2 at T = 20 K and 2.49 ohms-cm2 at room temperature. We note that there are essentially three regions; i) a region at low temperatures dominated by the process associated to trap-assisted tunneling; ii) in the range between 60 K and 125 K the generation-recombination (G-R) processes dominate; iii) at high temperatures is limited by the G-R current and the diffusion current. The diode architecture was a back-illuminated (BI) structure with a ring-shaped metallic contact in the GaSb substrate face. From the photodiode spectral response was obtained a responsivity of 0.65 A/W at a temperature of 20 K that compares well with the values reported by the more sophisticated and expensive MBE technique. 390 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SEM-553 ] Photoreflectance study of Mn delta-doped GaAs/InGaAs quantum wells G. Díaz-Monroy ([email protected]) 2 , A. Piedra-Lorenzana 2 , Y. Casallas-Moreno 2 , S. Gallardo-Hernández 2 , D. Cardona-Ramírez 2 , C. Hernández-Gutiérrez 2 , C. Mejía-García 1 , M. López-López 2 1 2 Departamento de Física, ESFM-Instituto Politécnico Nacional Physics Department, Centro de Investigación y de Estudios Avanzados del IPN In the past few years III-V semiconductor-based ferromagnetic materials such as GaAs doped with Mn have been intensively studied. The combination of semiconducting and magnetic properties aims to use the spin of carriers in novel spintronic devices. In order to realize these devices, optical, electric and magnetic characterizations of spintronic materials are necessary. In this work we studied Mn delta-doped GaAs/InGaAs quantum wells employing photoreflectance spectroscopy (PR). The heterostructures were grown by molecular beam epitaxy on GaAs(001) substrates. A set of samples was prepared with a constant thickness of the InGaAs quantum well, but the thickness of the Mn-delta layer was varied: 0.4 monolayers (ML), 0.8 ML, and 1.2 ML. We used Secondary Ion Mass Spectroscopy (SIMS) to confirm the Mn concentration in the samples. The PR spectra show the presence of damped oscillations at energies above the GaAs band-gap (Franz–Keldysh oscillations), which are a clear signature of the existence of intense internal built-in electric fields in the samples. In addition we observe two features at energies below the GaAs band-gap: at 1.41 eV which we assign to the Mn-delta doping, and at 1.40 eV which is assigned to the InGaAs quantum well. The variation of the PR characteristics as a function of the thickness of the Mn-delta layer is discussed. 391 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla SOL-GEL (SGE) Chairman: L. Irais Vera Robles (UAM-Iztapalapa) Sesión Oral [ SGE-102 ] Adsorption and Removal of Cadmium Ions from Simulated Wastewater Using Commercial Hydrophilic and Hydrophobic Silica Nanoparticles; a Comparison with Sol-Gel Particles Susana Vargas Muñoz 1 , Martha Shaday Martínez 2 , Maykel González Torres 1 , Sadott Pacheco Alcalá 4 , Francisco Quintanilla 2 , Antonio Rodríguez-Canto 3 , Rogelio Rodríguez Talavera ([email protected]) 1 1 Centro de Física Aplicada y Tecnología Avanzada, Universidad Nacional Autónoma de México, Campus Juriquilla, Apdo. Postal 0-1010, Queretaro, Qro., CP 76000, Mexico. 2 Universidad del Valle de México, Campus Queretaro, Queretaro, Mexico. 3 epartamento de Hidrobiología, DCBS, UAM-Iztapalapa, Apdo. Postal 55-534, México, D.F. 09340, Mexico. 4 nstituto Mexicano del Petroleo, Eje Central L. Cardenas 152, Apdo. Postal 14-805, C.P. 07730, Mexico. Adsorption and removal of cadmium ions from simulated industrial wastewater using hydrophilic and hydrophobic commercial silica nanoparticles, are reported. These results are compared with those obtained using sol-gel silica nanoparticles. Two types of dense commercial pyrogenic silica nanoparticles with different chemical groups on the surface were used to adsorb cadmium ions: Aerosil A130VS and R972. The pore absence in these particles reduces the surface area and, consequently, the concentration of active chemical groups appropriated for adsorption, as compared with the sol-gel particles that are highly porous; this effect is partially compensated by the small sizes available for these commercial particles. The concentration of cadmium ions was reduced: from 109 ppm to 0.01 ppm for A130VS, from 138 ppm to 1.44 ppm for R972 and from 123 to 0.005 ppm for sol-gel. The flocculation kinetics was obtained using Dynamic Light Scattering, and the amount of adsorbed cadmium in the sediment using Atomic Absorption Spectroscopy. 392 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SGE-210 ] Synthesis and characterization of a SiO2TiO2 coating by ultrasound – assisted sol-gel technique Juan Antonio López Rubio ([email protected]) 2 , Carlos Martinez Guzman 2 , Eduardo Arturo Elizalde Peña 2 , José de Jesús Perez Bueno 1 , Karen Esquivel Escalante 2 1 CIDETEQ 2 UAQ Nowadays, atmospheric pollution is dramatically increasing the presence of soiling on buildings due to the deposition of organic matter and other contaminants. Hence, the development of self-cleaning coatings,using TiO2 as a photocatalyst, has received special attention from researchers in recent years.The sol – gel synthesis was successfully modified by incorporating ultrasound. The chemical effects of ultrasound have been explained as the consequence of localized hot spots created during bubble collapse .For all ultrasound assisted reactions there exists an optimus power input or amplitude at which a specific reaction can be performed . The percentage of amplitude used in this research work was 40 % (26kHz) the irradiation was carried out for 10 min in a 5 s pulse mode , 5 s ON and 5s OFF mode. Tetraethylorthosilicate (TEOS) and titanium tetraisopropoxide (TTIP) have been employed as Si and Ti sources, respectively. Ethanol (EtOH) and water were used as solvents, while sulfuric acid assisted the catalysis of TEOS . A molar ratio TEOS/EtOH/H2O/TTIP/H2SO4 of 1/4/4/0.1,0.2,0.5/0.0004 was used. The water contact angle was measured and evaluated to characterize the effectiveness of the sols in providing hydrophobic protection. The water contact angle measurements were made using an optical tension meter under laboratory conditions, according to the sessile drop method. It was observed that according to an increase of the molar ratio of TTIP, hydrophobic efectiveness decreased. The innovation of this synthesis pertains to the application of a hydrophobic transparent nano-composite based on SiO2–TiO2 with self-cleaning properties. In addition, no toxic catalysts have been employed in the sol–gel process and the times of reaction have been reduced. 393 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ THF-238 ] Characterization of BST thin films for application Resistive Random Access Memories Juan Reséndiz Muñoz ([email protected]) 2 , José Luis Fernández Muñoz 1 , Miguel Ángel Corona Rivera 2 , Martín Zapata Torres 1 , Alfredo Márquez Herrera 3 , Enrique Valaguez Velázquez 4 1 CICATA-IPN 2 UASLP 3 UGT-Campus Salamanca-Irapuato 4 UPIITA-IPN Characterization of BST thin films for application Resistive Random Access Memories The resistive switching properties of barium strontium titanate (BST) as a thin film (1,2) are important because their potential applications in microelectronics devices. The parameters which govern the resistive switching behaviour have not been satisfied explain yet. The properties of BST thin films may be best known as deposited under controlled conditions of thermal and electrical insulation, temperature, stoichiometric composition, and deposition time, which can be achieved with the technique RF Co-Sputtering magnetron. Thin films of BST were deposited on quartz substrates with different values of electric power (120 watts divided between two magnetrons) with strontium titanate (BTO) and barium titanate (STO) targets, different temperatures (25, 374.8, 434.8, 494.8, 548.8 ºC and deposition times (since 60 until 72 minutes), gas flow Ar=18 sccm,O2=2 sccm, 30 mTorr, to achieve different stoichiometric composition and thickness. The transmittance spectrum of thin films show changes on its percentage depending on wavelength and temperature. We report values of Eg and resistivity (measured with 4 probes technical), when is variated the stoichiometric composition and deposition temperature. The Eg decreases and resistivity increases when deposition temperature is increased. These first results are important because they ones related to the mechanism of resistive switching behaviour when is aplicated forward and reverse bias voltage on metal-insulator-metal MIM decives based on BST. [1] R. Oligschlaegera, R. Waser, R. Meyer, S. Karthäuser, and R. Dittmann, Resistive switching and data reliability of epitaxial (Ba,Sr)TiO3 thin films, APPLIED PHYSICS LETTERS 88, 042901 (2006) [2] Wan Shen, Regina Dittmann, Uwe Breuer, and Rainer Waser, Improved endurance behavior of resistive switching in (Ba,Sr)TiO3 thin films with W top electrode, Appl. Phys. Lett. 93, 222102 (2008) 394 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SGE-248 ] Formation of Sol-Gel amorphous HfOxPMMA hybrid gate dielectric layer for Flexible and transparent thin film Transistors. Gouri Syamala Rao Mullapudi ([email protected]) 1 , Rafael Ramirez Bon 1 1 Material Science,Cinvestav Unidad Queretaro. Libramiento Norponiente #2000, Fracc. Real de Juriquilla. C.P. 76230 For flexible thin-film transistors (TFTs), hybrid gate dielectric materials are great current interest because of their high mechanical properties, low temperature processability, lowcost, and operating at low voltages. In this study we report here a vacuum-free solution processed novel organic/inorganic hybrid dielectric layer composed of HfOx-PMMA precursor solutions. The effect of hybrid solutions are studied with and without cross linking agent 3-Glycidoxy propyl trimethoxy silane (GPTMS). Dielectric films are readily prepared by Spin/Dip coating process with controlled thickness (~100nm) and then followed by cured at low temperatures (≤2000C) for compatibility of plastic substrates. The optical properties of the hybrid films are determined by UV-vis spectroscopy and the films are optically transparent in the visible range (400-700nm). The morphologies and microstructure of the films depended on the amount of GPTMS in the precursor solution and were characterized by FE-SEM. The films are homogeneous, amorphous moreover high smooth enough and very low roughness (≤1nm) observed by AFM. The chemical composition of the films and functional groups studied by XPS and followed by Fourier transform infrared spectroscopy (FTIR). Additionally these hybrid amorphous films are desired for electrical and dielectric properties such as reduced leakage current and Capacitance –Voltage properties of TFTs. 395 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SGE-249 ] Sol-Gel deposited ZnO-CdO thin films: Synthesis and Characterization E. Carro-Gastélum ([email protected]) 1 , M. P. Campos-Arias 1 , G. Alarcón-Flores 1 , M. A. Aguilar-Frutis 1 , J. A. Luna-Guzmán 1 1 INSTITUTO POLITECNICO NACIONAL CENTRO DE INVESTIGACIÓN EN CIENCIA APLICADA Y TECNOLOGÍA AVANZADA U. Legaria Calz. Legaria # 694, Col. Irrigación, Del. Miguel Hidalgo, C.P. 11500, México, D.F., México CdO and ZnO thin films are interesting Transparent Conducting Oxides that are studied because of their electrical and optical properties. ZnO is characterized for its wide direct energy band gap (~ 3.3 eV), high electron mobility, and high transparency in the visible range of the electromagnetic spectrum. CdO, on the other hand, is probably the oxide that exhibits one of the highest electrical conductivities, very close to the one shown by ITO thin films (~ 103 S/cm). These characteristics make CdO and ZnO important materials for different applications in Solar Cell technologies and in the Transparent Electronics. In this work, the Sol-Gel technique was used to obtain ZnO-CdO thin films with a composition ranging between ZnO and CdO. Pure CdO and ZnO thin films, and mixtures of them, were deposited from Zinc and Cadmium acetates. The main characteristics of the synthesis and their optical and electrical properties are presented in this work. A mixture of both oxides show a conductivity of about 6.2 S/cm, an electronic mobility of 0.43 cm2/V-s, and a carrier concentration in the range of 1019 cm-3. Higher and lower electronic conductivities were obtained in pure CdO and ZnO films, respectively. The films were characterized by UV-vis spectroscopy, Scanning Electron Microscopy, X-ray Diffraction, and the electrical properties were determined by Hall Effect. In resume, high quality ZnO-CdO thin films were obtained by the Sol-Gel deposition technique. The authors acknowledge the financial aid to carry out this work to Secretaría de Investigación y Posgrado del INSTITUTO POLITECNICO NACIONAL, grant # 20151155, and BEIFI-IPN Program. 396 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla Sesión Poster [ SGE-29 ] High Dose Thermoluminescence Dosimetry Performance of Sol-Gel Synthesised TiO2 Phosphors Ch. J. Salas-Juárez ([email protected]) 3 , R. Bernal 2 , C. Cruz-Vázquez 3 , V.E. Alvarez -Montaño 3 , V.M. Castaño 1 1 Centro de Física Aplicada y Tecnología Avanzada, Universidad Nacional Autónoma de México, Apartado Postal 1-1010, Querétaro, Querétaro 76000 México 2 Departamento de Investigación en Física, Universidad de Sonora, Apartado Postal 5-088, Hermosillo, Sonora 83190 México 3 Departamento de Investigación en Polímeros y Materiales, Universidad de Sonora. Apartado Postal 130, Hermosillo, Sonora 83000 México TiO2 is a ceramic materialwith many applications due to their different crystalline phases ( rutile, anatase and brookite [1]. It has attracted attention in several fields because its high mechanical strength, chemical stability and ion-conducting properties [2]. Moreover, in recent years, some research groups gained interest in the thermoluminescence features of TiO2 concerning their potential use as thermoluminescence dosimeter. In this work, we present the thermoluminescent characterization of Sol-Gel synthesized TiO2 phosphors exposed to beta particle irradiation. TiO2 was prepared by alkoxide sol-gel route using titanium tetrabutoxide as precursor, ethanol, water and ammonia as catalyst. Pellet-shaped samples were subjected to a thermal treatment at 700 °C for 6 h in air atmosphere, and then were exposed to radiation doses from 25 to 6400 Gy. The glow curves show a maximum located at 171 °C, and the integrated TL is a linear function of dose in the whole dose range studied. From the experimental results here presented, we conclude that TiO2 is a promising material to develop high dose TL dosimeters. References. 1.Cernea, M.; Secu, M.; Secu, C. E.; Baibarac, M.; Vasile, B. S.,. Journal of Nanoparticle Research 2011, 13 (1), 77-85. 2.F.Gonella,G.Mattei,P.Mazzoldi,G.Battaglin,A. Quaranta,G.DeandM.Montechi.Chem.Mal,11(1999) 814-821 397 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SGE-177 ] Study by EDS and X-ray of ZrO2 pure and doped with trivalent erbium, synthesized by the Sol-gel technique Raúl Gutiérrez Enríquez ([email protected]) 2 , Rebeca Sosa Fonseca 2 , Alma Mireya Arrieta Castañeda 2 , Miguel Ángel García Sánchez 1 1 Chemistry Department, Universidad Autónoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco 186, Vicentina, D. F. 09340, México 2 Physics Department, Universidad Autónoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco 186, Vicentina, D. F. 09340, México Analysis by microscopy SEM/EDS and X-ray about the effects on spectroscopic properties and morphological changes caused by the reduction of organic material is presented. These were made in both two different drying process, room temperature and annealing at 500 °C in a matrix of ZrO2 and in a ZrO2:Er3+, respectively. Additionally, these monolithic materials were synthesized with and without acid catalysis by the Sol-gel method. The results of microscopy SEM/EDS revealed that materials are synthesize homogeneously with a resolution of 90μm, which provides an analysis of the solid solutions, which confirms predominance in oxygen concentration in the matrix, against a little erbium concentrations in ZrO2:Er3+ sample, about 2% wt, approximately. The samples of pure zirconia without catalysis has a composition of 65% wt in oxygen and 35% wt of zirconium; where part of the 65% wt corresponds to remnants organic matter of the synthesis. On different way the sample with catalysis has a 60/40% wt composition of oxygen and zirconium, approximately. There is a minimum change of concentration with the use of an acid catalyst. X-ray spectroscopy shows a structural change of amorphous to a crystalline phase, when the sample of ZrO2 is subjected to heat treatment at 500° C. The X-ray spectra shows a tetragonal structure due to the heat treatment; It is important emphasize that EDS of the annealing material show that contains 35% wt of oxygen and 65% wt of zirconium content and the photoluminescence band show a UV-shift. 398 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SGE-229 ] Synthesis and characterization of TiO2 doped with SnO2 Karin Monserrat Alvarez Gomez ([email protected]) 1 , Joaquin Alvarado Pulido 1 , Blanca Susana Soto Cruz 1 , Miguel Angel Hernandez Espinosa 2 1 2 CIDS-BUAP ICUAP-Buap TiO2 and SnO2 nanoparticles were synthesized by sol-gel method from a precursor solution of titanium isopropoxide tetrachloride dehydrate tin. Obtained nanoparticles were heated at 500°C for 1hr in order to crystallize them. After, TiO2 was doped with SnO2 nanoparticles by a mixing technique, with a ratio of TiO2:SnO2 (0.1M: 0.01M). Obtained samples were characterized through different techniques such as: X-ray diffraction (XRD), energy backscattered spectroscopy (EDS), Raman and electron microscopy (SEM). In the case of XRD, different phases were observed in the nanoparticles like anatase and rutile which belongs to the TiO2 and cassiterite for SnO2. The atomic percentage ratio of the different materials and the presence of Ti, O and Sn was obtained by EDS. Bands positions of the samples were observed at 143, 396, 516 and 639 belonging to TiO2 through Raman characterization. Furthermore, the morphology of the samples was obtained by SEM, where a size less than 100nm was observed. Obtained results validate the proposed technique to obtain TiO2 doped with SnO2. 399 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SGE-277 ] Biomineralization of TiO2 Using a Genetically Engineered Bacteriophage Armin Hernández-Gordillo ([email protected]) 1 , Antonio Campero 1 , L. Irais Vera-Robles ([email protected]) 1 1 Department of Chemistry. Universidad Autónoma Metropolitana-Iztapalapa. San Rafael Atlixco 186, Col. Vicentina, C.P. 09340. México, D.F. Mexico. Peptides and proteins are the most common biomolecules used by organisms in inorganic synthesis; this process is best known as biomineralization. [1] Biomineralization can create wonderful nano, micro and macro structures under ambient conditions. Is for this reason that scientists are interested in mimic nature. In order to mimic the biomineralization process, scientists have used specific peptides, which show high affinity for some material and then they are used for its synthesis. The search of specific sequences is based on a combinatorial technique of molecular biology named biopanning. There are several reports of sequences with specificity to many inorganic materials such as metal nanoparticles and semiconductors. [2] In this way, we have chosen the peptide called H1 (HKKPSKS) [3], which has been reported to have anatase affinity to biomineralize TiO2. Through this approach, we have obtained anatase nanoparticles of ~5 nm in size at room temperature [4]. Thus, we are performing an experiment in which the filamentous bacteriophage M13 -virus that infect bacteria- is being genetic engineered in gene 8 (who express the major coat protein of virus) in order to insert the sequence of peptide H1. On other hand, M13 phage is able to self-assembly [5] as a liquid crystal depending on concentration, pH among others parameters. Thus, our aim is to obtain crystalline mesoporous structures of TiO2 using engineering M13 phage as template. The combination of knowledge from biology and chemistry can be a powerful tool for the synthesis of novel materials and the development of new technologies through ambient friendly techniques. References [1] Sarikaya, M.; Tamerler, C.; Jen, A. K.-Y.; Schulten, K.; Baneyx, F. Nature Mater. 2003, 2, 577. [2] Dickerson, M. B.; Sandhage, K. H.; Naik, R. R. Chem. Rev. 2008, 108, 4935. [3] Chen, H.; Su, X.; Neoh, K.-G.; Choe, W.-S. Anal. Chem. 2006, 78, 4872. [4] Hernández-Gordillo, A.; Hernández-Arana, A.; Campero, A.; Vera-Robles, L. I. Langmuir 2014, 30, 4084. [5] Chung, W.-J.; Oh, J.-W.; Kwak, K.; Lee, B. Y.; Meyer, J.; Wang, E.; Hexemer, A.; Lee, S.-W. Nature 2011, 478, 364. 400 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SGE-360 ] Luminescent ionogel based ionic liquid [Carb-Bzmim] Br Mariely Guadarrama R. ([email protected]) 1 , Antonieta García M. ([email protected]) 1 , Cesar A. Flores S. 2 1 2 Cerrada de Cecati s/n, Azcapotzalco, Santa Catarina, 02250 Ciudad de México, D.F. Eje Central Lázaro Cárdenas Norte 152 Col. San Bartolo Atepehuacan, México D.F. C.P 07730 The ionic liquids (IL) have the advantage of being used in various applications, among which as new materials in analytical chemistry, new solvents in electrochemical devices, green chemistry, among others; and the ability to retain its properties to be immobilized in a matrix of oxide acting as arranger for the formation of inorganic ionogeles, is one of the features that attracts attention of inorganic chemistry because of how they influence the physicochemical properties of LI in the construction of the network where the solid is confined (Eu3+) and how involved in the phenomenon of luminescence. [ SGE-413 ] Mn-Doped Zinc Silicate Phosphors Synthesized by Sol-Gel Method and Solid-State Reaction: A Comparative Study of their Optical and Structural Properties. Claudia Elena Rivera Enríquez ([email protected]) 1 , Ana Leticia Fernández Osorio ([email protected]) 1 1 Facultad de Estudios Superiores Cuautitlán, Campo 1. Universidad Nacional Autónoma de México. Ave. 1o de Mayo S/N, C.P.: 54740, Cuautitlán Izcalli, México. Mn-doped Zn2SiO4 is well-known as a green emitting phosphor due to its high luminescent efficiency, thermal and chemical stability. This material is widely used in technological applications such as cathode ray tubes, fluorescent lamps and plasma display panels [1]. Zinc silicate particles have been developed industrially by solid-state reaction. This method requires the application of a large amount of energy reaching its formation at temperatures higher than 1300°C. Several chemical methods are being developed with the aim to develop 401 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla low temperature routes. Sol-gel method has had the objective to obtain fine particles controlling particle size, shape and size distribution [2]. Solid solutions of Zn2-xMnxSiO4 (x = 0, 0.01, 0.03, 0.06, 0.09 and 0.12) powder phosphors were successfully synthesized by solid-state reaction and sol-gel method followed by post annealing treatments in air. X-ray powder diffraction (XRD), high resolution transmission electron microscopy (HRTEM) and photoluminescence spectroscopy (PL) were utilized to characterize the prepared samples. The samples synthesized by solid-state reaction at 1400°C showed average crystallite sizes of 80 ± 6 nm determined by XRD data. It was possible to reduce synthesis temperature of Zn2SiO4 at 800°C using the sol-gel method achieving crystallite sizes of 42 ± 2 nm. Crystallite size determined by Scherrer equation shows a close agreement with particle size found by HRTEM. In both methods crystallite size increases while increasing annealing temperature and decreases with increasing manganese concentration. PL spectra showed a broad emission band centered at 524 nm corresponding to the 3d5 electron transitions of Mn2+ under an excitation wavelength of 250 nm. Quenching manganese concentration are 6% and 3% mol for samples synthesized by solid-state reaction and sol-gel method, respectively. Samples made by solid-state reaction showed higher luminescent intensity. Reduction in luminescent intensity samples synthesized by sol-gel method is attributed to the presence of ZnO found as a byproduct of the reaction. In both series the emission intensity increase with increasing crystallite sizes. [1] Y. C. Kang, H.D. Park. Applied Physics A77 (2003) 529-532. [2] Masafumi Takesue, Hiromichi Hayashi, Richard L. Smith Jr. Progress in Crystal Growth and Characterization of Materials 55 (2009) 98-124. 402 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SGE-441 ] Synthesis and characterization of nanoparticles of KNbO3 by chemicals process on acid environment Jesus Alfredo Hernandez Marquez ([email protected]) 2 , Manuel Cortez Valadez 1 , Juan Francisco Hernandez Paz 2 , Jose Trinidad Elizalde Galindo 2 , Jose Rurik Farias 2 , Pierre Giovanni Mani Gonzalez 2 1 2 Centro de Investigación en Física, Universidad de Sonora Instituto de Ingeriería y Tecnología, Departamento de Física y Matemáticas, Universidad Autónoma de Ciudad Juárez Potassium niobate (KNbO3) is an important ABO3 material because of their pyroelectric, piezoelectric, dielectric susceptibility properties and linear and no linear optical effects. The KNbO3 nanoparticles were synthetized with chemical process that belongs to a variation of sol-gel method using an acid environment which was obtained using citric acid. The acid environment contributes to the reaction between K2CO3 and Nb2O5 making it control with the KNbO3 phase, the temperature and mixing time are important variables for the reactions too. After that, the exposition to different thermal annealing (800-1000 C) was important to increase the superficial area and crystalline limit of grain. X-Ray diffraction (XRD) and scanning electron microscopy (SEM) were used to ensure the quality of obtained KNbO3 nanoparticles trough structural parameters to analyze the phase and particles size for the morphology of nanoparticles respectively. 403 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SGE-569 ] Copper Doped Titania Prepared by Sol-GelMicrowave Method: Synthesis, Characterization, and Application Verónica De La Luz Tlapaya ([email protected]) 1 , Karina del Carmen Jiménez Córdova 2 , Ricardo Gómez Romero 1 1 2 Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa División Académica de Ingeniería y Arquitectura, Universidad Juárez Autónoma de Tabasco Titanium dioxide has attracted great attention in the fields of environmental purification, solar energy cells, photocatalysts, gas sensors, photoelectrodes and electronic devices. In addition, their high chemical stability, environmental friendliness, easy availability, and cost effectiveness makes TiO2 an ideal candidate as a photocatalyst [1]. The previous research works provided some promising methods to enhance the photoactivity of TiO2, involving metal or non-metal ions doping and co-doping. But nevertheless, the effect of doping on the activity depends on many factors, e.g. the method of doping, and the type and the concentration of dopant [2-3]. The synthesis of TiO2 by the sol-gel method has proven to be a very useful tool for photoinduced molecular reactions to take place on a titanium dioxide surface [4]. There are special variables that affect the photo-induced reactions, including particle size, phase composition, incident light and preparation method; for instance, anatase TiO2 nanoparticles have shown more photocatalytic activity than rutile TiO2 [5] In this work, we prepared a TiO2 precursor by sol-gel method, and samples copper doped TiO2 (1 and 3 % Cu) assisted by microwaves. We identified anatase phase in samples Cu doped TiO2. These materials were probed like photocatalysts in hydrogen production as main aim. Moreover, we observed that the incorporation of copper ions into the TiO2 structure seems to enhance the photoactivity of the system, and with it, was improved hydrogen production. References [1] T. Bak, J. Nowotny, M. Rekas, C.C. Sorrell, Int. J. Hydrogen Energy 27 (2002) 991– 1022 [2] R. Jaiswal, N. Patel, D.C. Kothari, A. Miotello, Appl. Catal. B Environ. 126 (2012) 47– 54. [3] R. Jaiswal, J. Bharambe, N. Patel, A. Dashora, D.C. Kothari, A. Miotello. Appl. Catal. B Environ. 168-169 (2015) 333–341 [4] Jang H.D., Kim S.K., Kim S.J., J. Nanopart. Res. 3 (2001) 141 [5] Scaflani, L. Palmisano, M. Schiavello, J. Phys. Chem. 94 (1990) 829 404 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla THIN FILMS (THF) Chairman: Sandra Rodil (IIM-UNAM) Giovanni Ramirez (Argonne National Laboratory USA) Sesión Oral [ THF-44 ] Yttria-stabilized Zirconia coatings on AISI 316L using the Ultrasonic Spray Pyrolysis technique by controlling the substrate temperature and the mixture of carrier gas Daniel Eduardo Villalobos Correa ([email protected]) 1,2 , Jhon Jairo Olaya Flórez ([email protected]) 1 , Ivan Romero-Fonseca 2 1 Facultad de Ingeniería, Departamento de Ingeniería Mecánica y Mecatrónica, Universidad Nacional de Colombia 2 Vicerrectoría de Investigación, Universidad ECCI In this research homogeneous coatings of Yttria-stabilized Zirconia on substrates of stainless steel AISI 316L were deposited. The focus was on two important aspects: the substrate temperature and composition of the gas mixture flow of air/nitrogen and its effect on corrosion resistance. The corrosion resistance was evaluated by the technique of electrochemical impedance spectroscopy (EIS) and the mechanical properties obtained by nanoindentation. The microstructure of the coatings was characterized by scanning electron microscopy (SEM) and confocal laser microscopy. Additionally, the crystalline structure was determined by X-ray diffraction (XRD). The optimization of the deposition parameters has yielded coatings of excellent quality, good adhesion and adequate corrosion resistance. More details on the corrosion modes showed in the deposited coatings are discussed in this work. 405 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ THF-47 ] Photocatalysis in thin films elaborated by thermal evaporation of BiOX (X = Br, Cl, I) for degradation of Rhb in water. Jose Luis Olivares Cortez ([email protected]) 1 , Enrique Manuel Lopez Cuellar 1 , Azael Martinez de la Cruz 1 1 UANL-FIME The use of organic dyes has been extensively increased in the last decades by a great variety of industries. One of these dyes is the Rhb, it belongs to the family of the xanthans which is used in groundwater research and dyeing cotton and silk, but recently its carcinogen potential has been discovered. In this sense, the pollution of water with Rhb is an interesting topic, and some semiconductor photocatalysis techniques had proven their efficacy to eliminate the organic pollutants and in an environmentally friendly manner. BiOX compounds present a strong absorption in the visible region, and are good candidates to be used in degradation of Rhb. This research has the goal to elaborate thin films of BiOX (X = Cl, Br, I) by thermal evaporation to evaluated the photocatalytic activity in degradation of Rhb and determine the degree of mineralization of organic dye. Also is measured the activity of BiOX powders, showing the thin films better activity than powders in degradation of this dye. 406 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ THF-113 ] Electrochemical deposition of SnS and Sb2S3 thin film semiconductor material for photovoltaic applications Nini Rose Mathews 1 1 Instituto de Energia Renovables Electrodeposition is a relatively simple and inexpensive deposition technology which can be scaled up easily. In the present work the development of tin sulfide and antimony sulfide thin films by electrochemical method will be discussed. SnS and Sb2S3 thin films are deposited on SnO2:F-coated transparent conductive oxide glass substrates by pulse electrodeposition. The potentials applied for the deposition of these semiconductor materials were determined by cyclic voltammetry measurements from their respective baths containing tin(11) and antimony(111) chlorides. Thiosulfate was used as the source for sulfur. The structural, morphological and the optical characterizations of the these films were carried out using Xray diffraction, Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and UV-VIS transmittance spectroscopy. The morphological characterizations revealed that the films were uniform and compact. The band gap of these materials was in the range of 1.3-1.7 eV with an absorption coefficient 105 cm-1 in the visible region. The films were photosensitive and had good electrical properties to be used as a photovoltaic absorber layer . Acknowledgements:- Authors acknowledge Maria Luisa Ramon Garcia for the XRD analysis. This work was supported by the projects: CONACYT Ciencia Basica 238869, IN107815, CeMIE-Sol P28 407 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ THF-119 ] Synthesis of V2O5 thin films produced by magnetron sputtering . Dwight Acosta ([email protected]) 1 , Argelia Perez 1 , Carlos Magaña 1 , Francisco Hernandez 1 1 Instituto de Física de la UNAM Vanadium oxide is a material that shows a phase transition of semiconductor to metal when is heated around of certain critical temperature. For the V2O5 compound,,this phase transition occur at 257±5°C. The study of vanadium compounds in thin film configuration, has received special attention in recent times because of their interesting electrochromic and thermochromic properties and potential uses as thermal sensing, optical switches, optoelectronic devices and energy saving devices with emphasis in the development of smart windows 1. In this work, vanadium pentoxide (V2O5) thin films were deposited by RF magnetron sputtering with different deposition conditions: with and without O2, using a V2O5 target . A power of 100 watts during 10 minutes was used to deposit vanadium oxide on corning glass pure and coated with a conductive layer of SnO2:F (FTO) with an average sheet resistance of 7Ω/sq . The films were deposited on substrates kept at room temperature and 400ºC respectively. The optical and electrical properties were characterized by optical spectroscopy in the visible and ultraviolet range and the Four Points Van der Pauw method, respectively. Likewise, changes in resistance as a function of temperature were performed. The surface composition and morphological properties were followed with X-ray photoelectron spectroscopy (XPS) measurements and electron microscopy techniques. Cyclic voltammetry experiments were performed in a potential range: E0= -2800mV to E= potential 2800 mV vs. a platinum reference electrode with a scanning rate of 1000 mV/s. The cyclic voltammogram exhibits the evolution of the formation of vanadium oxides until the electrochromic species be obtained. Cycling runs, were done for 1, 10 and 60 cycles respectively and the coloration and decoloration processes at different rates, were observed for all the cases. X-rays diffraction patterns reveals low crystallinity mainly in samples deposited at room temperature. For samples deposited at 400ºC , HREM micrographs confirm low crystallinity in our samples.From SEM micrographs obtained before and after voltammetry cycling it was observed that V2O5 films look regular and compact, with an uniform grain size distribution. From SEM micrographs of films deposited at room temperature and 400 ºC and after cyclic voltammetry experiments it were detected modifications in grains configuration and surface structural properties that might be related with sample degradation and loss of electrochromic activity as a consequence of mass and charge transport during the experiment. 408 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ THF-123 ] Influence of laser ablation plasma parameters on the incorporation of silicon into Al-Si-N thin films Laura P. Rivera-Reséndiz ([email protected]) 1,2, Enrique Camps 1 , Stephen Muhl 2 1 Departamento de Física, Instituto Nacional de Investigaciones Nucleares, Apartado Postal 18-1027, México D.F. C.P. 11801, México. 2 Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Apartado Postal 70-360, Coyoacán, México, D.F. 04510, México. Nitride based hard films as protective coatings for cutting and wear applications have received widespread attention in the last decades. Particularly, coatings based on Al-Si-N were developed to improve the hardness and oxidation resistance. Different techniques including chemical vapor deposition and magnetron sputtering have been used to grow these films. Pulsed laser deposition is a technique that allows the deposition of ternary systems, such as Al-Si-N, but has not been extensively used. In this study Al-Si-N thin films were deposited using simultaneous laser ablation of two targets (Al and Si, respectively) in a reactive atmosphere of N2, with a substrate temperature of 200 °C. The plasma parameters (ion kinetic energy and plasma density) were studied using a Langmuir planar probe and optical emission spectroscopy, this latter to measure the type of excited species present in the plasma. The ion energy and plasma density of the plasma formed during the ablation of the aluminum target was fixed at two levels of energy and for each of these two values, the parameters of the plasma obtained during the ablation of the silicon target were varied. For the case of high energies for both aluminum (230 eV) and silicon (80 eV) the plasma emission at a low working pressures (4 x 10-3 Torr) was mainly dominated by the emission from N2+ (at 391.4 nm), with some smaller peaks corresponding to ionized aluminum and silicon. When the working pressure was increased (10 x 10-3 Torr), the main emission was from excited and neutral aluminum and the emission from ionized molecular nitrogen species was strongly reduced. In the case when the lower value of both aluminum ion energy (105 eV) and silicon (52 eV) was used, the main emission corresponded to excited and neutral aluminum species which persisted for times much longer than after the laser pulse. However, the emission from N2+ (at 391.4 nm) decayed to low intensities at working pressures of 6 x 10-3 Torr were it was usually seen that the N2+ intensity was maximum when the high aluminum ion energies were used. In these different conditions samples were deposited and some properties such as structure, composition, hardness and optical transmittance were studied and are discussed in the present work. 409 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ THF-157 ] Corrosion behavior of ternary metal oxides films obtained by magnetron sputtering Jonatan Pérez Alvarez ([email protected]) 1 , Osmary Depablos Rivera 1 , Roberto Mirabal Rojas 1 , Sandra E. Rodil 1 1 Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Ciudad Universitaria, 04510, D.F., México The stainless steel passivity is attributed to the formation of metal oxide film in the surface. However, the austenitic stainless steel SS 316L have a poor corrosion resistance in solutions containing chloride ions (Cl-), since penetration of Cl- through the passive film, increased the corrosion rate and decrease the durability, limiting the application of this material in saline environments. Recent studies showed that metal oxides coatings inhibit the corrosion of the 316L SS. In this work we investigated the corrosion performance of two different ternary metal oxides, varying the composition of the Nb and Si in the Bi2O3 and in Nb2O5 respectively. The films were deposited on SS 316L substrates using a magnetron sputtering system. Compositional characterization was done by X-ray photoelectron spectroscopy. The structure of the films was analyzed by Raman spectroscopy and X-ray diffraction. The electrochemical evaluation of the films were investigated from potentiodynamic polarization, using a standard three electrode cell, employing the films as a working electrode, saturated calomel electrode (SCE) was used as a reference electrode and platinum grid as counter electrode, immersed in 10 wt.% NaCl; the corrosion rate was determined from Tafel extrapolation. 410 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ THF-208 ] Study on the effects of hydrogen dilution and B-doping on the suitability of a-SixC1-x:H thin films for biomedical and biological applications José Herrera-Celis ([email protected]) 2 , Claudia Reyes-Betanzo 2 , Abdu Orduña-Díaz 1 , Adrián Itzmoyotl-Toxqui 2 1 Centro de Investigación en Biotecnología Aplicada del Instituto Politécnico Nacional, ExHacienda San Juan Molino Carretera Estatal Tecuexcomac-Tepetitla Km 1.5, C.P. 90700, Tlaxcala-México 2 Instituto Nacional de Astrofísica, Óptica y Electrónica, Luis Enrique Erro #1, Santa María Tonantzintla, C.P. 72840, Puebla-México This work presents a study on the effects of hydrogen dilution and boron (B) doping on the formation of Si–C and Si–H bonds during the deposition of hydrogenated amorphous silicon carbide (a-SixC1-x:H) thin films by plasma-enhanced chemical vapor deposition. Methane and silane were used as precursor gases, while hydrogen and diborane were the diluent and dopant gases, respectively. The deposition parameters such as the temperature and the methane-silane gas flow ratio were selected according to the application. Therefore, temperatures of 150 °C and 200 °C, and methane-silane gas flow ratios of 0.70 and 0.85 were chosen in order to obtain carbon-rich films suitable for biomedical and biological applications. The deposition assessment was based on the results of different measurement techniques. Fourier transform infrared spectroscopy was used to analyze the formation of bonds. The effects of hydrogen dilution and B-doping on optical and electrical properties of the films were studied using UV-visible spectroscopy and electrical dark conductivity measurements. The surface morphology analysis was made by atomic force microscopy. The results show that, under the proposed deposition parameters, the hydrogen dilution and the B-doping affect mainly the formation of Si–H bonds, whereas the formation of Si–C bonds is governed by the methane-silane gas flow ratio. Furthermore, both the hydrogen dilution and the B-doping decrease the optical band gap and increase the conductivity of the films. Regarding the degree of disorder, the hydrogen dilution decreases it, while the B-doping increases it. Carbon-rich B-doped a-SixC1-x:H thin films with a root mean square roughness of about 1 nm, a conductivity of the order of 10-6 S/cm and a high density of Si–C bonds were obtained. These findings are important to incorporate the material in implants, implantable devices or biosensors. 411 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ THF-264 ] The surface plasmons resonances in the visible range of the silver-tin dioxide thin films system Narcizo Muñoz-Aguirre ([email protected]) 1 , Luis Felipe Rodríguez Llamas 1 , Omar Rosales Altamirano 1 , Lilia Martinez Perez 2 1 Instituto Politécnico Nacional, Sección de Estudios de Posgrado e Investigación, Escuela Superior de Ingeniería Mecánica y Eléctrica-UA. Av. Granjas, N° 682, Colonia Santa Catarina. Del. Azcapotzalco, CP. 02250, México, D.F. México 2 Unidad Profesional Interdisciplinaria en Ingeniería y Tecnologías Avanzadas del Instituto Politécnico Nacional, Av. IPN No. 2580, Col. Barrio La Laguna Ticomán, C.P. 07340, México D.F. México. The Surface Plasmons Resonances of silver-tin dioxide (Ag-SnO2) thin films system as a function of the wavelength of the incident light beam are determined. In order to determine the Plasmons Resonances in the visible spectrum range, calculations and plots of the reflectance spectra as function of the wavelength, at fix angle of incidence, were carried out using academic Maple software. In the calculations, the dielectric function of the SnO2 thin films was obtained fitting the Sellmeier model to the experimental data reported by Shamala et. al. , and the dielectric function of the silver films was determined using the Drude´s formula. The results showed that bilayer systems with thicknesses in the order of 35 nm and 10 nm of Silver and Tin Dioxide films, respectively, shown Resonances in the 375-800 nm range. Experimental measurements for the Ag-SnO2 system confirmed such theoretical results. The purpose of obtaining and tuning the resonances in a specific position is to work in the amplitude mode of operation using a monochromatic beam. Furthermore, thinking about future gas sensing applications, changes of the order of 10-4 in the refractive index of the air were theoretically studied resulting in shifts of the resonance positions of some nanometers, which can be measured by this SPR method. 1.- N. Muñoz-Aguirre, C. A. Andrade-Arreguin, C. Ávila-Salazar, P. Tamayo-Meza and L. Martínez Pérez. Optical characterization of low density polyethylene thin films by Means of Surface Plasmon Resonance. Optics of Surfaces and Interfaces 9 (OSI9), Septiembre 19-23 Akumal, México, 2011. 2.- N. Muñoz Aguirre, L. Martínez Pérez, J. A. Colin, E. Buenrostro González, Sensors 7(9), 1954 (2007). Acknowledgements. Work partially supported by Instituto Politécnico Nacional from México with the project number SIP-20151005. Authors also would like to acknowledge the technical assistance of Ing. Ana Berta Soto and QFB. Marcela Guerrero both from the Physics Department of CINVESTAV-IPN. 412 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ THF-308 ] The Seebeck Effect for Key Thin-Film Thermoelectric Materials as a Function of Thickness Horacio Estrada ([email protected]) 2 , Francisco J. Hernández-Cuevas 1 , Miguel A. Aleman-Arce 1 1 CNMN - Instituto Politécnico Nacional, Mexico, DF 2 Centro Nacional de Metrología, Queretaro, QRO ABSTRACT Results of a detailed study of the Seebeck effect for thin films of pure bismuth and antimony, with respect to platinum thin films will be presented. The characterization of the thermoelectric properties of thin films is aimed at identifying the optimum films for the implementation of various devices based on this effect including thermoelectric converters for metrology applications, high sensitivity temperature and biosensors, and thermoelectric power generators. Thin films deposited by DC-magnetron sputtering on polyimide films are investigated for their thermoelectric power with respect to platinum. The value of Seebeck coefficients is established using a simple but yet quite accurate experimental setup that considerably reduces most possible uncertainties. It will be shown that the dependence of the Seebeck coefficient with the film thickness for bismuth is opposite to that for antimony, and these variations are correlated with the films’ crystallographic structure, using XRD methods. For the thickness-range that has been thus far investigated, the values for thermoelectric power of Bi vary from -50 to -90µV/oC, higher than its bulk-value of -70µV/oC that has been long reported in the literature, while the ones for Sb vary from +23 to +28µV/oC, which concur with some reported data for films deposited by other methods, but lower that the bulkvalue of about +40µV/oC. The results of this study will be important to define the films for Bi-Sb alloys and other to optimize the Seebeck coefficient most applicable to the devices under consideration. 413 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ THF-328 ] Studies on optical, morphological, structural and electrical properties of CdS : Cu thin solid films that were synthesized by using chemical wet technique. Fernando Sánchez 4 , Gelacio Atondo 2 , Cristo Yee 2 , Oscar Velarde 2 , Miguel Aguilar-Frutis 1 , Manuel García-Hipólito 3 , Francisco Ramos-Brito ([email protected]) 2 1 CICATA Legaria - Instituto Politécnico Nacional Facultad de Ciencias Físico Matemáticas - UAS 3 Instituto de Investigaciones en Materiales - UNAM 4 Student in Facultad de Ciencias Físico Matemáticas - UAS 2 Thin solid films of ZnO were synthesized by employing chemical wet technique. Films were obtained as function of different parameters: precursors, deposition time and annealing temperature. Transmittance, Resistivity, Photo and Cathodoluminescence (PL, CL) at room temperature, XRD, HR-SEM, HR-TEM, and AFM studies were done. The thicknesses of the films were measured by using a surface profiler KLA-Tencor/P 15 obtaining an average thickness of 160 nm for all films. The surface of undoped films was conformed by splinter shaped nanoparticles with width distribution functions centered at around 35 nm and FWHM = 0.603 nm. The crystalline phase of films was cubic and invariant under changes in deposition time or precursors. All samples resulted with a = 5.82 A lattice constant, crystalline grain size of around 6 nm and preferred (111) orientation. The presence of monoclinic CdSO4 • H2O in undoped films was investigated. HR-TEM and XRD studies were in good agreement. HR-TEM shows a film surface conformed by regularly-spaced entities asterisk shaped of around 35 nm size composed by the superposition of several nanocrystals with dimensions lower than 10 nm. The films presented an energy gap of around 2.4 eV that move slightly with changes in deposition time and precursors. The PL and CL emission spectra present the free exciton emission and reveal the presence of structural defects. Defects were identified. The resistivity achieved was of 5.822 x 10 -5 ohm/cm. 414 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla INVITED TALK [ THF-344 ] Pushing the performance limits of electrical contact materials - connecting nano to macro Nicolas Argibay ([email protected]) 1 , Michael Chandross 1 , Blythe Clark 1 , Michael Dugger 1 , Somuri Prasad 1 1 Sandia National Laboratories From nano- and micro-electromechanical systems (NEMS/MEMS) to wind turbines and satellites, the desire to engineer electrical contacts with increasingly greater efficiency and reliability in increasingly more aggressive and demanding operating environments continues to provide ample motivation for both applied and fundamental cutting-edge, multi-scale and multi-disciplinary materials research. In this presentation we share new insights based on experimental and atomistic simulations on the fundamental mechanisms of wear and friction of metal contacts, the results of recent efforts to develop metal-matrix nanocomposite and high-temperature nanostructured binary metal alloy thin films, and end with a discussion of ongoing research efforts aimed at overcoming longstanding technical obstacles in the wind power and electronics industries. 415 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ THF-429 ] Temperature Dependence of Resistive Switching Memories based in Ultra-Thin Hafnium Oxide Dielectrics Rene Valderrama ([email protected]) 1 , Joel Molina 1 1 Electronics Department, National Institute of Astrophysics, Optics and electronics (INAOE), Tonantzintla, Puebla, 72000, Mexico. Resistance Random Access Memories (ReRAM) based in hafnium oxide and having different concentrations of oxygen vacancies are present in this work. They are a candidate for the next-generation of nonvolatile memory technology, because of their suitability against scaling down, low power consumption and fast switching speed. The structure of these ReRAM memories is simple just like a capacitor consisting of two metal electrodes and an insulator (MIM structure). For fabrication of these MIM structures, N-type Silicon wafers (100) with resistivity of 5-10 Ω•cm were used as substrate which were cleaned with standard procedures. Three different ReRAM devices were fabricated using stoichiometric HfO2, nonstoichiometric HfOx and HfOx-HfO2 as mixed layer, all deposited at 250°C by Atomic Layer Deposition technique using different exposure times to H2O precursor in order to promote oxygen-rich, oxygen-deficient and a stack layers, and the other precursor being TDMAH. Tungsten and aluminum were deposited by E-beam Evaporation under ultra-high vacuum conditions and they were used as bottom and top electrodes of the MIM structure respectively. After MIM fabrication a lithography process was applied to all samples in order to define the gate area which is 64e-6 cm2. It was reported that the resistance switching is due to the formation/dissolution of filaments inside the dielectric film, these filaments are created for the movement of oxygen vacancies which are repaired by Joule heating effect of the current through the filaments. Based on this phenomenon, the influence of test temperature on ReRAM memories was studied from I-V measurements, where different conduction mechanisms were fitted to experimental results in order to highlight physical parameters which can help to understand better the resistance switching of these memory devices and then improve their performance characteristics. 416 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ THF-462 ] Vanadium oxide compounded with silver prepared by pulsed laser deposition using a two parallel plasmas configuration Fernando Gonzalez Zavala ([email protected]) 5 , Luis Escobar Alarcon 2 , Dora Alicia Solis Casados 1 , Emmanuel Haro Poniatowski 3 , Rafael Basurto 4 1 Centro Conjunto de Investigación en Química Sustentable UAEM-UNAM Departamento de Física, Instituto Nacional de Investigaciones Nucleares 3 Departamento de Física. Universidad Autónoma Metropolitana Iztapalapa 4 Departamento de Quimica, Instituto Nacional de Investigaciones Nucleares 5 Doctorado en Ciencia de Materiales. Facultad de Química. UAEMex 2 Thin films of vanadium oxide compounded with silver were prepared by pulsed laser deposition using a two parallel plasmas configuration. Deposits on glass and silicon substrates using a Nd:YAG (1064nm) laser were obtained. High purity vanadium and silver targets were ablated in vacuum at working pressures close to 4x10-6mbar. During experiments the plasma parameters, mean ion kinetic energy and plasma density, of vanadium remain approximately constant while the plasma parameters of silver were varied in order to obtain different silver content in the deposited thin film. Afterwards, the thin films were subjected to thermal treatment at 450°C in order to obtain crystalline oxides. The obtained materials were characterized by Raman spectroscopy showing that the thin films were composed by mixtures of vanadium oxides, silver vanadate, and silver oxides in different proportions. XPS confirmed the existence of mixtures of V2O5, V2O3, VO2 and AgVO3, as well as the presence of AgO and AgO2 for films prepared at higher silver plasma densities. EDS results showed silver contents ranging from 6.2 to 17.4 at. % at corresponding to the lowest and the highest silver plasma density. Surface morphology was observed by SEM, characteristic vanadium pentoxide acicular structures were observed at low Ag contents; the length of such structures increases as the silver plasma density employed during the deposition experiment was increased. 417 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ THF-508 ] Surface processing of carbon fiber composites for the effective adhesion of primary structures in aeronautics applications Víctor Hugo Martínez-Landeros ([email protected]) 2 , Sandra Yesenia Vargas-Islas 2 , Serafín Barrera 1 , Khassan Mourtazov 1 , Jorge HerreraOrdóñez 2 , Gerardo Trápaga-Martínez 2 , Rafael Ramírez-Bon 2 1 2 Bombardier Aerospace México CINVESTAV - Unidad Queretaro Adhesive bonding techniques to join advanced composite materials for critical structures of the aircraft parts (critical load carrying component) need to be investigated to attain the vanguard of technology in design and manufacturing of aircrafts. It consists by preparing the surface of the composites based on carbon fiber, for efficient adhesion in primary structures and selecting the most appropriate methodology to measure the quality of surface preparation of such composites prior to bonding with other parties. This development results from tests of the composite materials, adhesives and mechanical quality tests under various bonding surface preparation of the composites. The analysis was performed by means of several spectroscopic and microscopic techniques, such as XPS, FTIR, SEM, AFM, etc., and a contact angle measurement technique which provides a direct, fast and easy measurement of the surface energy of the fiber composites. The ASTM D 5528-01, reapproved 2007 norm was employed for the analysis of the mechanical testing of the adhesively bonded carbon fiber composites. The mechanics of the linear elastic fracture is considered a tool for the failure of the laminate in composite materials with cracks or cuts in the plane, due to the presence of damaged zones in the tip of the crack; which is therefore applied to the study of delamination or fracture toughness. Keywords: Adhesive bonding, surface processing, contact angle, mechanical tests. 418 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ THF-530 ] Deposition and Characterization of CuS by Successive Ionic Layer Absorption and Reaction Obed Yamín Ramírez-Esquivel ([email protected]) 1 , Raquel Garza-Hernández 1 , Eduardo Martínez-Guerra 1 , Francisco Servando Aguirre-Tostado ([email protected]) 1 1 CIMAV-Monterrey, Alianza Norte 202, Parque PIIT, Apodaca, N.L., México 66628. The deposition of semiconductor materials for photovoltaics applications by solution methods is attractive because it implies low processing temperatures, low cost and large area. However the elucidation of the process reaction paths is of tremendous importance in order to understand how to control the physical and chemical characteristics of the deposited films. Successive Ionic Layer Absorption and Reaction (SILAR) is a solution-based technique that allows for the control of composition and thickness by simply manipulating the solution composition, ion concentration and solution temperature. The technique consists of successive dipping of a substrate on separate cation and anion precursor solutions with intermediate DIW rinsing steps. Cu2S is a p-type II-V semiconductor with a direct band gap of 1.2eV employed in solar cells as the active layer or as a precursor for ternary or quaternary systems such as CIGS, CIS and CTS. Upon thermal annealing in vacuum CuS decomposes into Cu2S and S2 through the following reaction 4CuS = 2Cu2S + S2. In this work CuS thin films were deposited by SILAR on glass substrates from CuSO4, Na2S and Thiourea precursors in aqueous solutions. The deposition speed depended on the concentration of NH4OH of the cationic solution and type of anionic precursor as well as on its concentration. X-ray photoelectron spectroscopy analysis was used to understand the nucleation and initial stages of CuS formation during the first deposition cycles. The dependence of the optical characteristics, morphology, grain structure, chemical composition and electrical characteristics as function of the deposition conditions will be discussed. 419 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla Sesión Poster [ THF-7 ] Fabrication of hydrophobic films from ps with contact angle above 90º Rafael Catarino ([email protected]) 1 , Elías Pérez 1 1 IF-UASLP This work is aimed to the fabrication of polymeric rough surfaces from the mixture of two immiscible polymers: Polystyrene (PS) and Poly-(Butyl Methacrylate) (PBMA), both dissolved in a common solvent: Tetrahydrofuran (THF). The interest of this work is to generate hydrophobic and super hydrophobic films from structured surfaces (nano and micro) in order to shape these two polymers when the solvent suddenly evaporates. All samples were submitted to the following analysis: Infrared Spectroscopy (FTIR) for the evolution of surface chemical species, Atomic Force Microscopy (AFM) for supervising the topography of the films and, Contact Angle (CA) to modulate the water wettability extension on the films and the evolution of this parameter for each treatment. [ THF-25 ] Chemical bath deposition of zno thin films and their application in field effect transistors María del Carmen Camacho Alcántar ([email protected]) 3 , Rodolfo Bernal 2 , Dainet Berman Mendoza 2 , Catalina Cruz Vázquez 3 , Víctor Manuel Castaño 1 1 Centro de Física Aplicada y Tecnología Avanzada, Universidad Nacional Autónoma de México, Apartado Postal 1-1010, Querétaro, Querétaro 76000 México 2 Departamento de Investigación en Física, Universidad de Sonora, Apartado Postal 5-088, Hermosillo, Sonora 83190 México 3 Departamento de Investigación en Polímeros y Materiales, Universidad de Sonora, Apartado Postal 130, Hermosillo, Sonora 83000 México ZnO films have been studied as the active channel material in thin-film transistors because it is an n-type semiconducting material with a wide band gap of 3.3 eV, chemically inert and it exhibits thermal stability. Moreover, it can be growth along certain crystalline planes if deposited on the suitable substrate.[1] 420 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla In this work, we report the fabrication of ZnO film– based Metal Oxide Semiconductor Field Effect Transistors (MOSFET). The used ZnO films were synthesized by a chemical bath deposition method, and their electrical properties measured after being subjected to different thermal treatments. The fabricated transistors have a structure consisting of a low resistivity Si substrate, a SiO2 thin layer as the insulator gate, the synthesized ZnO thin film as the active channel, and two Al contacts as source and drain terminals; by the backside of the silicon wafer a thin Al layer was deposited to generate the gate electrode. With this structure, saturation currents dependent on the thermal annealing of the ZnO films are observed in the I-V curves. [1] H. C. Cheng, C. F. Chen and C. C. Lee, Thin Solid Films, Vol. 498, No. 1-2, 2006, pp. 142-145. [ THF-46 ] Scattering of Gaussian electromagnetic beams by a stack of graphene layers Juan Sumaya Martínez ([email protected]) 1 , Raúl Salazar Hernández ([email protected]) 1 1 Physics Dept., Universidad Autonoma del Estado de Mexico. Instituto Literario 100, Col.Centro. Toluca, Edo. Mex. The interaction of Gaussian electromagnetic beams with single-layer graphene and a stack of parallel graphene sheets at arbitrary angles of incidence is studied. It is found that the scattered energy is strongly dependent on the polarization (TM or TE- polarization), on the angle of incidence, on the thickness hi of layers and on the beam diameter L. Finally we show that a periodic stack of planar graphene layers has features similar to those of an onedimensional photonic crystal, with gaps at certain frequencies. 421 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ THF-48 ] Single and twofold SiOx films deposited by HFCVD: Hydrogen flow and annealing effect on the photoluminescent properties Diana Elizabeth Vázquez Valerdi ([email protected]) 1 , Jose Alberto Luna López 1 , Godofredo García Salgado 1 , Jesús Carrillo López 1 , Alfredo Benítez Lara 1 1 IC-CIDS Benemérita Universidad Autónoma de Puebla, Ed. 103 C o D, Col. San Manuel, C.P. 72570 Puebla, Pue., México. In this work, the hydrogen flow and annealing effect on the photoluminescent properties of the single and twofold non-stoichiometric silicon oxide (SiOx) films is reported. The single and twofold SiOx films are obtained by hot filament chemical vapor deposition technique in a temperature range from 795 to 829 °C at two hydrogen flows, 25 and 75 sccm. The single and twofold SiOx films as-grown and annealed are characterized by Fourier transform infrared spectroscopy and photoluminiscence. FTIR reveals, so that, the both films composition changes with the hydrogen flow. In general FTIR spectra show vibrational bands related to the presence of hydrogen in the both films as-grown. This band disappears after thermal annealing. The single SiOx films exhibit PL intensity bigger than the twofold SiOx films. The single SiOx films as-grown exhibit PL spectra with two main peaks at 700 and 750 nm. These bands are more intense as the grown temperature is decreased as well as the hydrogen flow decreased. When the single SiOx films are thermally annealed the PL intensity is more intense as the grown temperature is increased as well as the hydrogen flow increased, at the same time that the presence of hydrogen disappears. The twofold SiOx films as-grown exhibit PL spectra with a main peak at 750 nm. The film deposited at 795°C-25sccm / 795°C25sccm has the biggest PL intensity. The PL intensity increased after the twofold SiOx films are thermally annealed. Also the spectra width increased, exhibiting a broad spectrum from 600 at 875 nm. These results lead to good possibilities for proposed novel applications in optoelectronics devices. 422 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ THF-82 ] Next generation environment protection sensor Vinoth Kumar Jayaraman ([email protected]) 1 , Yasuhiro Matsumoto 1 , Maria de la luz Olvera Amador 1 1 Department of Electrical Engineering, CINVESTAV-IPN, Mexico City, Mexico Propane is a colorless, odorless, flammable and non-toxic gas, which is one of the major hydrocarbon in LPG (Liquefied Petroleum Gas) used in day to day life. In addition, propane is an important source of energy. When propane is used as a fuel in vehicles, causes less pollution than other petroleum products. It is predicted that there will be propane gas stations than other petroleum products. Therefore, it is mandatory to design a gas sensor to detect propane leaks to ensure safety for the environment. In this work, we are reporting results about sputtered zinc oxide (ZnO) thin films for manufacturing propane gas sensors. Zinc oxide thin films were deposited by the radio frequency (RF) magnetron sputtering technique, at different RF on glass substrates. Structural, morphological, and gas sensing properties of the thin films were studied in detail. Structural analysis of all deposited films was performed by X-Ray diffraction (XRD) to confirm the wurtzite hexagonal ZnO phase, the preferred growth orientations, and the crystallite size. Scanning Electron Microscopy (SEM) technique was used for analyzing the surface morphological changes as a function of the RF power. Variations in RF power resulted in change in the grain size and the thickness of the films at similar deposition conditions. Gas sensing performance was tested in a propane gas atmosphere at different operation temperatures, and different propane concentrations. Sensitivity of sputtered ZnO thin films were in three orders of magnitude even at low concentration of gas. 423 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ THF-83 ] A simple and cost-effective zinc oxide thin film sensor for propane gas detection Vinoth Kumar Jayaraman ([email protected]) 1 , Arturo Maldonado Alvarez 1 , Maria de la luz Olvera Amador 1 1 Department of Electrical Engineering, CINVESTAV-IPN, Mexico City, Mexico In this work, we have reported a cost-effective thin film of zinc oxide (ZnO) sensor for propane gas detection. ZnO thin films were deposited on soda lime glass by ultrasonic spray pyrolysis using zinc acetylacetonate as a precursor in the starting solution. Thin film deposition was carried out at 450°C, by varying the water content in the spraying (starting) solution. Structural, morphological, and gas sensing properties were studied in detail. Variations in the water content resulted change in crystallinity, geometries, and gas sensitivity. ZnO thin film exhibited maximum sensitivity ~7, when measured at 100°C. [ THF-84 ] Simulation of a device for laminar flow generation in a SPU system Jorge Carmen Flores Juan ([email protected]) 2 , Evaristo Isac Velázquez Cruz 2 , Guillermo Juárez López 2 , Rafael Martínez Martínez 2 , Julián Javier Carmona Rodríguez 2 , Edgardo Yescas Mendoza 2 , Ciro Falcony 1 1 Centro de Investigación y de Estudios Avanzados de lIPN, Departamento de Física, Av.IPN 2508, Col.San Pedro Zacatenco,C.P. 07360 México D.F 2 Universidad Tecnológica de la Mixteca, Carr. A Acatlima km 2.5, Huajuapan de León, Oaxaca. CP 69000. Ultrasonic Spray Pyrolysis (SPU) system produced a droplet size that is direct function of two parameters. The first parameter is the vibration frequency of piezoelectric, since the higher the frequency of vibration the drop size generated is smallest and the second parameter, are the conditions in the which the aerosol is generated. A laminar flow is associated with an order along the path followed by the droplets composing the spray, that is a turbulent flow is prevented. So, in this work, a theoretical comparative study is performed of the influence of the nozzle geometry and the volumetric flow of carrier gas to obtain a laminar flow of aerosol in a SPU system. The study was performed with the SolidWorks 424 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla 2013 software. To simulate four different nozzle geometries were used, the best results were obtained with a geometric shape of circular type with four boosters of air distributed evenly around a circular section where the aerosol emerges. To generate the laminar flow, an air flow was used at a rate of 10 and 15 LPM, the first present with minus turbulence to the nozzle exit. [ THF-90 ] Wear performance of expanded austenite obtained by high temperature pulsed plasma nitriding of austenitic stainless steel. J.C. Díaz-Guillén ([email protected]) 3 , J.C. Díaz-Guillén 1 , E.E. Granda-Gutiérrez 3 , J.L. Acevedo-Dávila 3 , R. Muñoz-Arroyo 3 , J.A. DíazGuillén 2 , A. Garza-Gómez 3 1 2 Dirección de Cátedras. Consejo Nacional de Ciencia y Tecnología. México D.F. División de Estudios de Posgrado e Investigación. Instituto Tecnológico de Saltillo. Saltillo México 3 Gerencia de Desarrollo Tecnológico. Corporación Mexicana de Investigación en Materiales S.A. de C.V. Saltillo México Expanded austenite (S) has been identified as crystalline phase with remarkable properties when it is used for wear or abrasion applications. This phase is produced through introduction of atomic nitrogen on the surface of austenitic stainless steel by the use of plasma assisted processes as ion nitriding. The good properties of this solid solution have been attributed to both, the surface structural strain phenomenon, and the generation of high compressive stresses promoted by nitrogen introduction in the octahedral interstitial sites of austenite. It is also known that nitriding treatment at temperatures above 440°C promotes the detrimental of corrosion properties as a consequence of chromium nitrides precipitation. In this sense, in order to avoid decreasing in corrosion properties, typical treatment is carried out for periods up to 6 h. In the present work, pulsed plasma nitriding at high temperature and short time was carried out on 316L austenitic stainless steel. A free chromium nitride layer of expanded austenite with 8 mm in thickness was identified on the surface of 316L samples through Xray Diffraction and Scanning Electron Microscopy. Pin on disk wear test, performed using 52100 steel balls as a static friction partner, shows the significant drop of the friction coefficient of expanded austenite in respect to untreated sample and the consequent decrease in the wear volume. Obtained results promise an important decrease in the nitriding process duration which can result in a considerable energy saving for this technological process. 425 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ THF-105 ] Europium decorated graphene films Veronica Janette Cedeño Garcidueñas ([email protected]) 4 , Ricardo Rangel Segura 4 , Pascual Bartolo Pérez 5 , Luis Mariano Hernández Ramírez 3 , Rafael García Gutiérrez 2 , Donald Homero Galván Martínez 1 1 Departamento de Fisicoquímica de Materiales, CNYN- UNAM Ensenada. 2 Departamento de Investigación en Física, Universidad de Sonora 3 División de Estudios de Posgrado, Facultad de Físico-Matemáticas, Universidad Michoacana de San Nicolás de Hidalgo 4 División de Estudios de Posgrado, Facultad de Ingeniería Química, Universidad Michoacana de San Nicolás de Hidalgo 5 División de Física Aplicada, CINVESTAV-IPN Unidad Mérida The room temperature mobility, transparency, thermal conductivity and high Young’s modulus properties of graphene have attracted the attention in many fields and make graphene a promising candidate for applications in electronic, energy storage devices and sensors [1-3]. Graphene is a bidimensional material where its carbon atoms bonded together in a hexagonal lattice. Since graphene was discovered, many synthesis routes have been studied to produce large-area graphene. Chemical vapor deposition is the most suitable method to prepare easily transferable films [4]. Despite of their excellent properties, graphene may be doped in order to promote changes on their electronic, chemical and magnetic properties for application in electronic devices [5]. The synthesis of graphene begins with the choice of copper foil due to low solubility of carbon and a gaseous source of carbon such methane. Copper films were deposited by spin plasma coating, and further introduced in a 1 in diameter tube furnace, under an Ar/H2 gas mixture at atmospheric pressure. After annealing the Si/copper substrate for 10 min, graphene was growth at 1000°C using a methane flow, for 30 min. The films were decorated with europium at 800°C under inert atmosphere (Ar) and europium nitrate pentahydrate being used as precursor. Samples were characterized by AFM (Atomic Force Microscopy), RAMAN and TEM (Transmission Electronic Microscopy). The characterization shows regular deposition of graphene and a uniform europium film. [1] Hu B., Ago H., Ito Y., Kawahara K., Tsuji M., Magome E., Sumitani K., Mizuta N., Ikeda K. and Mizuno S. 2012. Epitaxial growth of large- area single –layer graphene over Cu (111)/sapphire by atmospheric pressure CVD. Carbon, 50, 57-55. [2] Bernard L.S., Spina M., Jacimovic J., Ribic P.R., Walter A., Orbeli D.Y., Horvath E., Forró L. and Magrez A. 2014. Functionalized graphene grown by oxidative dehydrogenation chemistry. Carbon, 71, 11-19. 426 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [3] Yao Y. and Wong Ch. 2012. Monolayer graphene growth using additional etching process in atmospheric pressure chemical vapor deposition. Carbon, 50, 5203-5209. [4] Bhaviripudi S., Jia X., Dresselhaus M., Kong J. 2010. Role of kinetics factorsin chemical vapor deposition synthesis of uniform large area graphene using copper catalyst. Nanoletters, 10, 4128-4133. [5] Ruitao Lv. and Terrones M. 2012. Towards new graphene materials: doped graphene sheets and nanoribbons. Materials Letters, 78, 209-218. [ THF-118 ] Structural, optical, electrical properties of spray pyrolized Mo:WO3 and TiWO3: thin films Dwight Acosta ([email protected]) 1 , Carlos Magaña 1 , Francisco Hernández 1 1 Instituto de Física de la UNAM The influence of molibdenum and titanium doping on WO3 thin films produced with a low cost pneumatic spray pyrolysis equipment, in the structural, electrical, optical and electrochromic properties has been investigated .Tungsten trioxide in thin film configuration is a very interesting material with optical, electrical and electrochromic properties which make it suitable for practical and advanced technological applications.The use of electrochromic and thermocromic materials for energy saving purposes is a subject of intensive research around the world. Electrochromic behavior of tungsten trioxide thin films have been studied extensively for last 30 years due to their potential applications in display devices, rear view windows and smart windows for energy saving purposes.Mo:WO3 and Ti:WO3: thin films have been deposited on FTO/Glass substrates by thepulsed chemical spray technique at a substrate tempertature of Ts = 450°C. The effects of doping concentration in the starting solution on structural, optical electrical and electrochromical properties were followed by the XRD, SEM, HREM, AFM, van der Pauw and cyclic voltammetry experimental techniques. The Mo:WO3 and Ti:WO3 thin films present for all the cases, a regular and compact surface but grain size distribution and morphology show differences as the metals concentration is increased. There is a noticeable improving in conductivity and carrier density when the Mo and Ti concentrations are increased in the starting solution. The electrochromic properties of Mo:WO3 and Ti:WO3: thin films are revisited and correlated when possible with the parameters used during the synthesis . The electrochromic phenomena was induced in an electrochemical cell using the Cyclic Voltammetry technique. The charge diffusion coeficients during the electrochromic coloration associated in turn with cathodic and anodic peaks, present different values for equivalent Mo and Ti atomic concentration in the starting solution used for the films deposition. 427 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ THF-140 ] Pulsed laser deposition of zinc vanadium oxides from a ZnV2O6 target J.G. Quiñones-Galván 3 , R. Lozada-Morales 6 , Enrique Camps 5 , Y.A. González-Rivera 6 , S. Jiménez-Sandoval 2 , E. Campos-González 4 , M. Zapata-Torres 1 , A. Pérez-Centeno 3 , M.A. Santana-Aranda 3 1 CICATA-IPN, Unidad Legaria, Mexico D.F.11500, Mexico Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Unidad Querétaro, Apartado Postal 1-798 Querétaro, Qro, 76001, México 3 Departamento de Física, Centro Universitario de Ciencias Exactas e Ingenierías, Universidad de Guadalajara, Boulevard Marcelino García Barragán 1421, Guadalajara, Jalisco, Mexico, C.P. 44430 4 Departamento de Física, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, P.O. Box 14-740, México D. F., 07360, México 5 Departamento de Física, Instituto Nacional de Investigaciones Nucleares, Apartado postal 18-1027, México D.F., C.P. 11801 6 Facultad de Ciencias Físico-Matemáticas, Postgrado en Física Aplicada, Benemérita Universidad Autónoma de Puebla, Av. 14 sur y Av. San Claudio, Col. San Manuel, Puebla, Mexico 2 Thin films of different zinc vanadium oxide compounds were grown on glass substrates at room temperature by means of the pulsed laser deposition technique. A polycrystalline ZnV2O6 target was used for the ablation process. The target was prepared by the melt quenching method at a temperature of 1000°C using a starting mixture of ZnO and V2O5. The films were annealed at 500 °C in air. The physical properties of the as-deposited as well as the annealed samples were analyzed as a function of deposition pressure and laser fluence. It was found that the deposited compounds are highly influenced by the background gas pressure used during the deposition process. The samples were structurally characterized by X-ray diffraction, Raman spectroscopy and transmission electron microscopy. The asdeposited films are amorphous. After the thermal treatment mixtures of vanadium oxides together with the ternary compound Zn2V2O7 were found. The proportions of each compound present in the sample depend on the deposition pressure. The optical characterization of the films was carried out by means of UV-Vis and PL spectroscopies. Surface morphology of the samples was analyzed by scanning electron microscopy. Structures with a variety of sizes and shapes were found in the annealed films. 428 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ THF-143 ] Structural and optical properties of Sb2S3 thin films deposited by vacuum evaporation R.G Sotelo Marquina 1 , N.R Mathews 1 , X. Mathew ([email protected]) 1 1 Instituto de Energía Renovables, Universidad Nacional Autónoma de México, Temixco, Morelos, 62580, México In this work we present the physical properties of vacuum evaporated Sb2S3 thin films. The as-deposited films were amorphous and highly resistive. The film changed to polycrystalline after annealing at 250 oC. The crystalline size of the film showed a systematic increase with annealing temperature. The estimated values of lattice parameters were a= 1.1 nm b = 1.13nm and c = 0.384 nm. At temperatures above 350 oC traces of Sb2O3 were observed. Morphological studies showed a compact and void-free film surface. The band gap calculated from optical study was about 2.1 eV and 1.87 eV respectively for as-deposited and the film annealed at 350 oC. The films were photosensitive. Acknowledgements:- Authors acknowledge Maria Luisa Ramon Garcia for the XRD analysis, Jose Campos and Gildardo C. Segura for technical support in material characterization. This work was supported by the projects: CONACYT Ciencia Basica 238869, PAPIIT- IN107815, and CeMIE-Sol P28. 429 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ THF-146 ] Effect of deposition potential on physical properties of electrodeposited Sb2S3 thin films R.G Avilez Garcia 1 , C.A Meza 1 , M. Pal 2 , N.R Mathews ([email protected]) 1 1 Instituto de Energías Renovables, Universidad Nacional Autónoma de México, Temixco, Morelos 62580, México 2 Instituto de Física, BUAP, Av. San Claudio y Blvd. 18 Sur Col. San Manuel, Ciudad Universitaria, C.P. 72570, Puebla, México Thin films of Sb2S3 were fabricated by pulse electrodeposition on ITO glass substrates from aqueous solution containing 0.5 mM SbCl3 and 0.25 mM Na2S2O3. The deposition was carried out by applying potential pulses; the deposition potential (Von) was applied for 10s which was followed by a dissolution potentials (Voff) for 10s. The thickness of the film was controlled by the number of cycles. In the present work, we investigated the effect of variation of deposition potential on the physical properties of Sb2S3 thin films. The films were deposited at different Von: - 0.7V, -0.72 V, and -0.75V versus SCE. The dissolution potential was kept constant at 0.1 V versus SCE. The structural, morphological and the optical characterizations of the as deposited and annealed films were carried out using Xray, SEM, AFM, Raman spectroscopy and UV-VIS transmittance spectroscopy. The films deposited at a potential of Von -0.72 V and Voff + 0.1 V vs SCE after annealing at 300 oC in N2/S atmosphere were nearly stoichiometric, polycrystalline and photoconductive. The photo conductivity of these films were in the range of 4 x10-7 (ohm-cm)-1 . Acknowledgements: Authors acknowledge Maria Luisa Ramon Garcia for the XRD analysis, Jose Campos and Gildardo C. Segura for material characterization. This work was supported by the project: CONACYT Ciencia Basica 238869, PAPIIT-IN107815, and CeMIE-Sol P28. 430 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ THF-190 ] Studies on optical and morphological properties of ZnO thin films as function of the synthesis technique employed. Carlos Fernández 3 , Iván García Payán 3 , Manuel Pérez 3 , Alejandro Ibarra Delgado 3 , Luis Castaños 3 , Gelacio Atondo 1 , Cristo Yee 1 , Oscar Velarde 1 , Manuel García-Hipólito 2 , Francisco Ramos-Brito 1 1 Facultad de Ciencias Físico Matemáticas - UAS Instituto de Investigaciones en Materiales - UNAM 3 student in Facultad de Ciencias Físico Matemáticas - UAS 2 Thin films of ZnO were synthesized by employing three techniques: Spray Pyrolysis, Chemical Bath and Spin Coating. Films were obtained as function of different parameters for each technique. Specular Reflectance, Transmittance, Photoluminescence (PL) at room and low (20K) temperature and Scanning Electron Microscopy studies were done for all samples. A comparison between energy gaps of all films is presented. The PL studies reveal films that have an intense exciton emission (384 nm) and poor visible emission (defects) and films that have poor exciton emission and intense visible emission, depending of the technique employed and its parameter values. The visible emission present two principal bands centered at 510 and 630 nm that were associated with typical structural defects. An energy diagram that shows the differences in the excitation and decay mechanisms for ZnO obtained by the three different techniques is presented. The films present morphology conformed by nanoparticles that depends of the technique employed for the synthesis. 431 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ THF-203 ] Study of Magnetic Interactions in Zn1xMnxO/ Si (100) Thin Films Carlos William Sánchez ([email protected]) 2 , Katherine Gross 2 , Wilson Lopera 2 , María Elena Gómez 2 , Pedro Prieto 1 1 Center of Excellence for Novel Materials CENM, Universidad del Valle, A.A. 25360, Cali, Colombia 2 Thin Film Group, Department of Physics, Universidad del Valle, A.A. 25360, Cali, Colombia The effects of Mn concentration on the crystal structure, morphological and magnetic properties of Zn1-xMnxO (0< x <0.3) thin films have been investigated by varying the deposition temperature (300 oC < Td < 600oC) and thickness systematically. Thin films growth was performed by RF sputtering technique with an oxygen pressure of 5.0x102mbar from Zn1-xMnxO targets with a stoichiometric composition on (100) Si substrates. X-ray diffraction (XRD) measurements reveal a (002) out-of-plane texture of the films and did not reveal any Mn-based oxides compounds. The magnetic properties of the films have been measured using vibrating sample magnetometer (VSM) at various temperatures with fields up to 3KOe. Ferromagnetic ordering at room temperature has been evidenced in all samples. Magnetic interactions have been studied using Delta-M plots as proposed by Thamm and Hesse[1], their method uses the natural relationship between the initial curve and hysteresis loop for the description of interactions of single-domain particles with uniaxial anisotropy dispersed in a nonmagnetic matrix. With this method it was possible to recognize magnetizing as well as demagnetizing interactions depending on Mn doping. Acknowledgments: This work has been partially supported by CENM-UNIVALLE and COLCIENCIAS-UNIVALLE research project C.I. 7917, C.C.10510, contract 2013-0002 and UNIVALLE research project titled “Development of room-temperature semiconducting oxide nanostructures for silicon-based spintronics” with C.I. 7775. [1] S. Thamm and J. Hesse, “A simple plot indicating interactions between single-domain particles”, Journal of Magnetism and Magnetic Materials, Vol. 154, pp. 254-262, 1996 432 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ THF-211 ] Thin films of silicon dioxide-silver nanoparticles (SiO2/Ag) by dip-coating María del Carmen Flores Rodríguez ([email protected]) 1 , Fernando Díaz Monge ([email protected]) 1 , Fernando Roberto Vélez Tenorio 1 , Esaú Solano Ruiz 1 1 Academia de ingeniería en materiales, Instituto Tecnológico Superior de Tlaxco, Predio Cristo Rey Ex-Hacienda de Xalostoc S/N, Carretera Federal Apizaco-Tlaxco Km. 16.8, Tlaxco, Tlaxcala. Thin films of silicon dioxide-silver nanoparticles (SiO2/Ag) were synthesized, by the dipcoating method to obtaining a homogeneous and high quality coating, for photocatalytic applications, specifically for carbon monoxide (CO) to carbon dioxide (CO2) oxidation. The synthesis of all solutions of SiO2/Ag was prepared from reduction of nitrate silver salt reagent grade with sodium citrate, previously prepared of colloid silicon dioxide (SiO 2)1. The deposition was carried out on substrates glass on their surface chemically treated with piranha solution to obtain a thickness of 3 µm by a dip coating, with a withdraw and immersion rate of 100 mm/min and immersion time of the substrate in the solution, it was 6 seconds with coating time 2 minutes. The obtained samples were heat treated in a tubular furnace, to improve their adhesion to the substrate. For the structural and morphological surface characterization samples, electron microscope (SEM) observations were carried out. The composition and thickness of samples were characterized by profilometry and Raman spectrophotometry. Acknowledgements. To technological institute and academy of engineering materials. References 1. W. Stöber, A. Fink, E. Bohn, J. Colloid Int. Sci., 1968 (26) 62 433 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ THF-217 ] Obtaining thin films of titanium dioxide (TiO2) by the Dip-Coating Ana Olivia Quintero Pérez ([email protected]) 1 , Esaú Solano Ruiz ([email protected]) 1 1 Ingeniería en Materiales, Instituto Tecnológico Superior de Tlaxco, Predio Cristo Rey ExHacienda de Xalostoc S/N, Carretera Federal Apizaco-Tlaxco Km. 16.8, Tlaxco, Tlax. Thin films of titanium dioxide (TiO2) microspheres for photocatalytic applications carbon monoxide (CO) to carbon dioxide (CO2) oxidation, on which gold nanoparticles (Au) are supported, whose synthesis is performed in aqueous solution from auric tetrachloride (1mM), using a concentration of 3 mM sodium citrate as reducing agent heated to 80 °C for 15 min. The synthesis of TiO2 microspheres were conducted by the sol-gel method Stober. Obtaining an average diameter of 0.12 µm. Deposition of films were carried out on glass substrates on their surface chemically treated with piranha solution to a thickness of 170 nm by immersion in colloidal sol using a dip-coating with immersion-emersion rate of 100 mm/min, with a residence time of 6 seconds, and 2 min drying . Each of the films obtained were thermally treated in a tubular furnace to obtain the desired phase (anatase) in an oxidizing atmosphere, after which a sharp increase was observed in the adhesion of the film deposited on the substrate surface. SEM analysis was performed subsequently, profilometry and Raman analysis, for determination of the surface morphology, thickness and phases present. Acknowledgements. To technological institute and academy of engineering materials. References. 1. Suh HMS, Choi JR, Hah HJ, Koo SM, Bae YC (2004) J Photochem Photobiol A Chem 163:37. 2. E. Nieto, F. Fernández, P. Duran y C. Moure. Instituto de Cerámica y Vidrio. CSIC. Arganda del Rey. Madrid. 3. Lee, P. C., Meisel, D. Journal of Physical Chemistry 1982 (86) 33. 4. W. Stöber, A. Fink, E. Bohn, J. Colloid Int. Sci., 1968 (26) 62 5. D.Y. Nadargi, et.al. Journal of Alloys and Compounds 2010 (496) 436. 434 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ THF-247 ] Functionalization and characterization (aSiC:H) films Ana Laura Perez Coyotl ([email protected]) 3 , Orlando Zaca Moran 3 , Valentín López Gayou 3 , Abdu Orduña Diaz 3 , Placido Zaca Moran 1 , José Luis Herrera Celis 2 , Claudia Reyes Reyes Betanzo 2 1 2 Benemérita Universidad Autónoma de Puebla, Instituto de Ciencias, Pue, México Instituto Nacional de Astrofísica, Óptica y Electrónica,Santa María Tonantzintla, Pue,México 3 Instituto Politécnico Nacional, CIBA-Tlaxcala, Tepetitla, Tlax, México Thin films of a-SiC:H can be used as devices biolgicas applications have better stability chemistry and biocompatibility compared to crystalline silicon carbide (Si-C), which are being proposed as transducer biosensors for the detection of pathogenic microorganisms. In this work samples of a-SiC:H obtained by Plasma Enhanced Chemical Vapor Deposition PECVD were functionalized films were prepared by self-assembling 3aminopropyltrimethoxysilane in anhydrous toluene. Fourier transform infrared spectroscopy (FTIR) and Atomic force microscopy AFM have shown process of funcionalized. The presence of the amine group is evidenced in the peak at 1562 cm-1related to deformation mode, and the two peaks at 3295 and 3368 cm-1 corresponding to symmetric and asymmetric stretching modes, respectively. The peak at 1484 cm-1 and the shoulder at 1635 cm-1 correspond to the symmetricand asymmetric NH3 deformation modes FTIR spectra indicate that film growth initially proceeds by adsorption of 3-aminopropiltrimethoxy silano to the aSiC:H surface followed by siloxane condensation, and after an extended period of time 3aminopropiltrimethoxysilane molecules accumulate on the underlying APTES film by either covalent or noncovalent interactions. The surface topographies were observed using AFM we observed the presence of many aggregates. The formation of aggregates may result from the physical adsorption on the a-SiC:H of silanes prepolymerized in the solution, but it may also be acase of surface nucleation. 435 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ THF-254 ] Electrochemical, microstructural and mechanical characterization of TiHfN coatings deposited by Sputtering Erika Luna Torres ([email protected]) 1 , Leandro García González 2 , Julián Hernández Torres 2 , Luis Zamora Peredo 2 , Daniel de Jesús Araujo Pérez 2 , Héctor Herrera Hernández 3 1 Instituto de Ingenieria, UV 2 MICRONA, UV 3 UAEM In this work, TiHfN coatings were fabricated by Sputtering onto stainless steel 316, using pressure values of 3.0x10-6 Torr, 4.0x10-6 Torr, 5.0x10-6 Torr and 6.0x10-6 Torr. The obtained TiHfN coatings were evaluated by Electrochemical Impedance Spectroscopy to study their corrosion resistance behavior, in an aggressive environment of NaCl at 0.5M exposed for 42 days. The microstructure and morphology of the coatings were studied by X-ray Diffraction and Scanning Electron Microscopy. Additionally, hardness and vibrational modes were obtained by Vickers indentation and Raman Spectroscopy respectively. Electrochemical impedance results shows two time constants one at high frequency, which associates the interface of the TiHfN coating with the electrolyte, and another at low frequency to the specimen adsorbed on the coating, filling the pores, and causing a more homogenous structure. Impedance values of 170000 ohm-cm2 were obtained. By scanning electron spectroscopy was observed that the grain size decreases as the base pressure increases, being the morphology of the sample at 6x10-6 Torr the most homogenous. The obtained hardness values were about 29 GPa. With the X-ray diffraction results, the formation of a ternary cubic phase of HfTiN2 was observed, with an intense reflection at 35.303° wich is related to an preferential orientation of (1 1 1). However, at a minor pressure of 3x10-6 Torr a change in the preferential orientation is seen to (2 0 0) at 40.991°. By Raman Spectroscopy four bands were observed: the first order optical mode (O) at 415cm-1, the first order optical mode and acoustic mode (O+A) at 680 cm-1 for the bond of HfN, the second order transversal acoustic mode (2LA) at 475cm-1 for the TiN bonding and the transversal optical mode (TO) at 558 cm-1. The results demonstrated that the base pressure affects the microstructure of the coatings as well as the efficiency of the protection against corrosion, unlike the hadrness which do not affect the corrosion protection efficiency. The coatings synthetized at a pressure of 6x10-6 Torr, are the most homogeneous with low porosity and therefore, they have a better electrochemical behavior. This research was supported by CONACYT by the project 154516. We thank at M.C. Daniel Araujo Pérez, the M.I. Ayesha M. Courrech Arias for technical support and M.C. Angélica Gutiérrez Franco by FESEM measurements. Keywords: Sputtering, TiHfN, EIS, XRD, SEM, Raman, Vickers. 436 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ THF-261 ] Structural and optical properties of zinc blende ZnO thin films Lilia Martinez-Perez ([email protected]) 3 , Narcizo Muñoz-Aguirre ([email protected]) 2 , Jesus Eduardo Rivera-Lopez 2 , Orlando Zelaya-Angel 1 1 Departamento de Física del Centro de Investigación y de Estudios Avanzados del IPN, CP. 07351, México, DF. 2 Instituto Politécnico Nacional, Sección de Estudios de Posgrado e Investigación, Escuela Superior de Ingeniería Mecánica y Eléctrica-UA. Av. Granjas, N° 682, Colonia Santa Catarina. Del. Azcapotzalco, CP. 02250, México, D.F. México 3 Unidad Profesional Interdisciplinaria en Ingeniería y Tecnologías Avanzadas del Instituto Politécnico Nacional, Av. IPN No. 2580, Col. Barrio La Laguna Ticomán, C.P. 07340, México D.F. México. Among the different phases in which zinc oxide can solidify in crystalline structure hexagonal wurtzite (WZ), cubic zinc blende (ZB), cubic rock salt (RS), hexagonal graphitelike, tetrapods are reported. Wurtzite is the crystalline stable phase in bulk at normal temperature and pressure. Other phases are stable in special conditions, for instance, ZB is the stable phase of nanoparticles condensed from smoke for less than 20 nm in size [1]. It is well known that ZnO thin films in ZB phase have been obtained in epitaxial growth on cubic substrates containing only a small number of monolayers. Recently, zinc oxide thin films in cubic zinc blende (ZB) crystalline phase on glass substrates by means of the spray pyrolysis technique were reported [2]. X-ray diffraction spectra showed that the ZB-ZnO films grow highly oriented along the (004) crystalline direction. Atomic Force Microscopy images of the surface exhibit nanometric structures with the approximated aspect of circular nanodiscs in accordance with the spherical structures observed by means of Scanning Electron Microscopy images. Optical absorbance measurements indicated that the forbidden energy band gap is 3.18 ± 0.02 eV. Luminiscence spectra for zinc blende films showed two bands at positions of 2.14 and 2.38 eV. Fluorescence spectra for hexagonal ZnO are centered at 2.83 eV. For zinc blende ZnO the fluorescence spectra showed bands centered at 3.27, 2.81, 2.64, 2.56 and 2.50 eV. In this work, a discussion about of the preliminary optical results is presented. [1] Shiojiri M, Kaito C, J Cryst Growth 1981;52:173. [2] L. Martínez-Pérez, N. Muñoz-Aguirre, S. Muñoz-Aguirre and O. Zelaya-Angel, Materials Letters 139 (2015) 63–65. 437 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla Acknowledgements. Work partially supported by Instituto Politécnico Nacional from México with the project number SIP-20151005. Authors also would like to acknowledge the technical assistance of Ing. Ana Berta Soto and QFB. Marcela Guerrero both from the Physics Department of CINVESTAV-IPN. Authors give thanks to Dra. Margarita Mondragón Chaparro by the using of their facilities from the Sección de Estudios de Posgrado e Investigación de la ESIME Unidad Azcapotzalco. [ THF-263 ] Study of the influence of thermal oxide thickness and rhodamine 6G concentration on the fluorescent properties of PSi single layers. Viridiana Aca-López ([email protected]) 1 , Estela Gómez-Barojas 1 , Rutilo SilvaGonzález 3 , J. Alberto Luna-López 1 , Claudia Reyes-Betanzo 2 , Enrique Sánchez-Mora 3 , Francisco Flores-Gracia 1 1 CIDS-IC, Benemérita Universidad Autónoma de Puebla. Apdo. Postal 196, Puebla, Pue. 72000. México. 2 Instituto Nacional de Astrofísica Óptica y Electrónica. Tonantzintla, Puebla, México 72840 3 Instituto de Física, Benemérita Universidad Autónoma de Puebla. Apdo. Postal J-48, Puebla, Pue. 72570. Key words: Porous silicon, Rhodamine 6G, Fluorescence Dye molecules embedded in solid state matrices have emerged as potential non linear optical materials. Different methods to trap organic molecules within solid substrates have been developed, including direct soaking of the host with dye solutions where the chemical bond between organic molecules and inorganic matrices is weak (hydrogen bonding, Van der Waals interactions, etc). This class of hybrids can be obtained through impregnation of solid hosts with solution of the desired molecule [1,2]. In the other hand, rhodamine is a fluorophore that presents good photophysical properties such as high absorption coefficient, high fluorescent quantum yield, high photostability and relative long emission wavelength. One common use of rhodamine is for labeling antibodies. In the present work, the effect of rhodamine 6G (Rd-6G) concentration in the fluorescence of infiltrated Porous silicon single layers has been studied, and due to the cationic character of Rd-6G, the effect of SiO2 thickness thermally grown on PSi to enhance the Fluorescence properties of PSi has been studied as well. PSi single layers have been synthesized by electrochemical etching of polished silicon p-type wafers (100) orientation and 0.01-0.02 Ω∙cm resistivity. Silicon substrates were chemically degreased and native residual surface oxide removed before 438 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla anodizing. The etching solution contained ethanol (purity 99.5%), hydrofluoric acid (45%) and glycerol (99%), at volumetric proportions 60:30:10. Porous silicon single layers were synthesized in a two electrodes electrochemical Teflon cell. The as anodized PSi single layers were thermally oxidized since it is known that the rhodamine is a cationic dye that interacts preferentially with oxygen terminated PSi. Two oxidation conditions were used. Then, the PSi single layers were silanized by dipping them into a solution formed with 2.5 v/v of 3mercaptopropyltrimethoxysilane (MPTS) in 2-Propanol solution for 15 min. Finally, they were infiltrated by dipping them into a solution containing Rd-6G and ethanol as solvent, for 1 h. The Rd-6G concentration in the infiltrating solutions was varied from 0.4 to 4.0 mM with 0.4 mM increment. From the comparison of Fluorescence spectra of PSi single layers slightly oxidized with the ones of thicker oxidized, it is proved that Rd 6G is well adsorbed on the PSi oxidized layers but a very thin oxide enhances the FL of the infiltrated PSi layers while a thicker one is opaque to the PSi fluorescence. Furthermore, the intensities of Fluorescence spectra have shown a non linear relation of fluorescence intensity with respect to Rd-6G concentration. Acknowledgement. This work has been partially supported by CONACYT through a scholarship. The authors acknowledge Dr. Mariano Aceves Mijares from INAOE for his help in the samples fluorescence measurements. References: [1] P. Proposito and M. Casalboni, Handbook of Organic-Inorganic Hybrid Materials and Nanocomposites, Vol. 1 (American Scientific Publishers, 2003). [2] R. Reisfeld. Opt. Mater. 16 (2001) 1. 439 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ THF-286 ] Synthesis and characterization of gallium oxide thin films prepared by sputtering. Elizabeth Galván 1 , Mario Fidel García Sánchez ([email protected]) 2 , Orlando Zelaya 1 , Marcelino Becerril 1 1 2 Departamento de Física, CINVESTAV- IPN, A.P. 14-740, C.P. 07000, México D.F. Unidad Profesional Interdisciplinaria de Ingeniería y Tecnologías Avanzadas, Instituto Politécnico Nacional, Av. IPN No 2580, Gustavo A. Madero, C.P. 07340, México D.F. Galium oxide thin films have been prepared on single-crystalline silicon substrates and quartz at room temperature by sputtering. The synthesis was prepared from a target with a mix of gallium nitride and metallic gallium. Influence of RF power and pressure was evaluated. The morphology and structure were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman, ellipsometry, profilometry, optical absortion (UV) and photoluminiscence (PL). Even when gallium nitride is representative in the target, Raman and UV measurements show that the obtained films were composed by gallium oxide. PL measurements show wide bands, in the range of 400-650 nm, which are associated with defects in the structure. The refractive index measurements indicate the presence of dense materials. Keywords: gallium oxide thin films, sputtering, photoluminiscence. 440 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ THF-296 ] Structural, optical and morphological characterization of CdS thin films for organic solar cells. Susana Meraz Dávila ([email protected]) 1 1 CINVESTAV Cadmium sulphide thin films were grown by photochemical deposition technique (PCD) from an aqueous ammonia-free solution at room temperature. Thin films were synthesized at different deposition times from 60 to 300 minutes; and were characterized by X-ray diffraction, optical transmission spectroscopy and scanning electron microscopy. Preliminary results demonstrated polycrystalline and highly oriented films, having an hexagonal phase with a preferred orientation at plane (0 0 2), homogeneous smooth films were observed with a clear change in thickness with respect of deposit time, having a uniform size and shape of CdS grains very well adhered to the substrate surface, with a high quality and good absorption in the visible region with a band gap of 2.3 eV. The CdS/Poly(3-hexylthiophene-2,5-diyl) (P3HT) hybrid devices were fabricated by drop casting process and different material contacts were evaluated; the influence of UV radiation and photovoltaic performance was studied with respect to the power conversion efficiency exhibiting efficiencies from 0.007 % for P3HT:CdS hybrid devices. The photochemical deposition proposed in this work is a direct, fast, simple, and inexpensive via process and due of this optimal features has a great potential for photovoltaics device applications. 441 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ THF-298 ] Enhancement photocatalytic activity of ZnTiO3-CdS composites films prepared by sputtering process Yuliana de Jesus Acosta-Silva ([email protected]) 1 , Arturo MendezLopez 2 , Orlando Zelaya-Angel 1 1 Depto. de Física, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Avenue IPN No. 2508, 07360 Mexico City, DF, Mexico 2 Sección de Electrónica del Estado Solido (SEES), Depto. de Ingeniería Eléctrica, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Avenue IPN No. 2508, 07360 Mexico City, DF, Mexico ZnTiO3-CdS composites films were prepared on glass substrates by sputtering process and their photocatalytic activity toward the degradation of methylene blue (MB) was measured. ZnTiO3-CdS films were characterized by diffraction (AFM), X-ray diffraction (XRD), UV–vis diffuse reflectance spectroscopy (UV-vis DRS), scanning electron microscopy (SEM) and, high resolution transmission electron microscopy (HRTEM). The ZnTiO3-CdS fims were found to be more active than pure ZnTiO3. The highest activity of ZnTiO3-CdS composites was due to coupling of two semiconductor nanoparticles reduce the recombination of electron-hole pairs and consequently achieving a higher photocatalytic activity. 442 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ THF-303 ] Determination of adhesiveness between a biodegradable material (PLA) and cellulose Magdalena Trujillo ([email protected]) 2 , Alejandro Vargas ([email protected]) 2 , Alfredo Maciel 1 , Marissa Morales 1 1 2 Materials Research Institute, UNAM Plastics processing lab, Design and Mnufacture department, Faculty of Engineering, UNAM Nowadays, biodegradable materials have been the most important upswing for the plastic industry. The government's concern to maintain a country free of solid waste has led researchers and scientists to develop materials and processes that contribute to the requested demands. The following work is based on the study of adhesive compatibility between a biodegradable material and a cellulose-based material. Obtaining biodegradable material in film form was performed under the extrusion process, designing the die by means of rheological principles allowed to obtain a preferential orientation, thus favoring the union between both materials. Through analysis and tests of adhesion under international standards, the quality of the bond was determined among the materials presented. References [1] M. Madrid Vega y J. M. Martín Martínez, Tecnología de la adhesión, España: Departamento Técnico de Loctite, 2009. [2] C. Rauwendaal, Understanding Extrusion, München: Carl Hanser Verlag, 2010. [3) L. Tin Sin , A. Razak Rahmat y W. A. Wan Abdul Rahman, Polilactic Acid, PLA Biopolymer Technology and Aplications, Oxford: Elsevier Inc, 2013. [4] National Institute of Industrial Research, The Complete Book on Biodegradable Plastics and Polymers, Delhi: Asia Pacific Business Press Inc., 2006. 443 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ THF-311 ] Structural characterization of layers of GaAs (Mn,Cr) and multilayer of GaAs / (Mn,Cr) grown by magnetron sputtering rf J. Doria ‐ Andrade ([email protected]) 1 , R. Medina ‐ Echavarría 3 , C. Pulzara ‐ Mora 3 , R. Bernal ‐ Correa 3 , A. Rosales ‐ Rivera 2 , A. Pulzara ‐ Mora 3 1 Escuela de Física, Universidad Nacional de Colombia, sede Medellín. A.A. 568, Medellín, Colombia. 2 Laboratorio de Magnetismo y Materiales Avanzados, Universidad Nacional de Colombia, sede Manizales. A.A. 127, Colombia 3 Laboratorio de Nanoestructuras Semiconductor, Universidad Nacional de Colombia, sede Manizales. A.A. 127, Colombia. Diluted magnetic semiconductors (DMS) based on III-V doped with Mn, Cr and Co are of great scientific and technological interest because they are materials in which the magnetic and transport properties are coupled so that the magnetization state modify the properties of the material transport. In this paper the results of the preparation and characterization of GaAs layers are as follows: Mn by rf magnetron sputtering on glass substrate and silicon in order to study their properties estructructurales. The growth was carried out alternating layers of GaAs /Mn and GaAs/Cr layers and GaAs (Mn) and GaAs (Cr) from targets GaAs ,Mn y Cr during certain time periods. In the XRD analysis (θ - 2θ) it was observed a characteristic peak at 2θ = 66.1° due to the addition of Mn in the GaAs matrix. In addition to the main peaks appeared GaAs not defined, such as (220) and possibly other peaks correspond to phases α- Mn and Ga5Mn8 as a function of temperature and the content of Mn -. Cr. Also better growth observed in GaAs / Mn on glass substrate at low temperatures for Mn. 444 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ THF-327 ] Fabry-Perot filters in the UV as a result of oxidized porous silicon multilayer María del Rayo Jiménez Vivanco ([email protected]) 2 , Godofredo Gacía ([email protected]) 6 , Francisco Morales 5 , Hector Juárez 7 , Mauricio Pacio 4 , Tomas Díaz 1 , Gabriela Nieto 3 1 2 Becerril CIDS-BUAP, Ed. 103-C, Col. San Manuel. Puebla, Pue. 3 Caballero 4 Castillo 5 Morales 6 Salgado 7 Santiestaeban This work presents an experimental study of the evolution of the spectral reflectance of porous silicon multilayers (PSM), which were obtained by electrochemical anodization of p+ type crystalline silicon substrates in aqueous hydrofluoric acid solutions and ethanol. The Fabry-Perot filter (FPF) produced by the PSM were obtained by alternating high and low refraction index of porous silicon PS with two Bragg reflectors and an active layer. The dependence of the porosity on the effective refractive index for porous silicon is limited by curves for the two-component media: silicon and air, using the Bruggeman effective medium approximation, this simple model is applicable to porous materials. FPF were subjected to a thermal oxidation process creating an oxidized porous silicon that induce a shift of the response to the ultraviolet (UV) from 505 to 370 nm in the peak minimum of the reflectance spectrum. The shift is explained as due to the formation of silicon dioxide, which has a lower refractive index than that of silicon. The oxidation causes changes in the optical characteristics of FPF, decrease the refractive index and the optical path, while keep the physical thickness, this due to the good penetration of the oxide and the design of the PSM. It was used a model to predict the behavior of our FPF that contains refractive index of silicon, silicon dioxide and air. Characterization of FPF was performed by UV-Vis-NIR spectroscopy before and after the oxidation process. Keywords: Oxidized porous silicon, Fabry-Perot filter, Ultraviolet. 445 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ THF-348 ] Synthesis of Sr²⁺ doped SnO2 coatings and modified with pmma applied for corrosion protection Ana Karen Acero Gutiérrez ([email protected]) 1 , Ángel de Jesús Morales Ramírez ([email protected]) 1 , Jesús Gilberto Godínez Salcedo 2 1 CIITEC-IPN Cerrada de Cecati s/n, Azcapotzalco, Santa Catarina, 02250 Ciudad de México, D.F. 2 ESIQIE-IPN U. Prof Adolfo López Mateos, Gustavo A. Madero, Ciudad de México, D.F. Nowadays, some materials, because its highly demanding operative conditions, need to present a superior corrosion resistance, wear resistance, high hardness and nontoxic. In this work, SnO2 coatings doped with strontium have been developed by sol-gel method using tin (II) chloride and strontium acetate as matrix and dopant precursors respectively; furthermore, the sol was modified by the incorporation of PMMA (polymethylmethacrylate) to compare their properties against corrosion process when is deposited on 304 stainless steel by dipcoating technique. Chemical evolution of the sol-gel process, crystal structure and morphology were examined by Fourier Transformed Infra-Red, X-Ray Diffraction, Scanning Electron Microscopy and Atomic Force Microscopy techniques, and the effect of the effect of the content of strontium (Sr²⁺) and PMMA were studied. The corrosion protection of the prepared coatings will be evaluated in simulated marine environment in 3 wt. % aqueous NaCl solution by potentiodynamic polarization. 446 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ THF-359 ] Processing of TaN by UHV sputtering Yuri Lizbeth Chipatecua Godoy ([email protected]) 1 , Oscar Ceballos Sanchez 1 , Zeuz Montiel Gonzalez 1 , Jhon Jairo Olaya Florez 3 , Wencel De La Cruz 2 , Alberto Herrera Gomez 1 1 2 CINVESTAV-Unidad Queretaro. Queretaro, Qro. 76230, Mexico Centro de Nanociencia y Nanotecnología. Universidad Nacional Autónoma de México, 22860, Ensenada, B.C., México 3 Departamento de Ingenieria Mecanica y Mecatronica, Universidad Nacional de Colombia, Botoga D.C., Colombia The transition metal nitride films deposited by PVD techniques, such as reactive magnetronsputtering, are well established for modifying mechanical properties on the surface. This is the case of TaN coatings that have excellent properties as hard films and have been extensively used in industry to protect base materials against fatigue, wear, corrosion and many other surface-related damage phenomena. These properties include high hardness and conductivity, chemical inertness, wear and corrosion resistance, chemical and thermal stability and biocompatibility. In this study, TaN films were deposited using an ultra-high-vacuum (UHV) sputtering system. The working pressure was ~ 5×10-3 Torr and the base pressure 1×10-8 Torr. The processing conditions (substrate temperature, Ar and N flow rate, bias, and discharge current) were optimized to obtain high quality TaN films. The composition was evaluated using xray photoelectron spectroscopy (XPS) and XPS-Sputter. Mechanical properties such as hardness and adherence were evaluated using nanoindentation and pin on disc tests. The thickness was characterized through perfilometry. Acknowledgments The authors would like to acknowledge Martín Adelaido Hernandez and José Alfredo Muñoz for his technical support. 447 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ THF-371 ] Synthesis and characterization of CdTe nanoparticles embedded within a silicon dioxide matrix Andrea Pamela Chavelas González ([email protected]) 4 , Arturo Hernández Hernández 2 , Luis Alberto Hernández Hernández 3 , Alejandra roció García Sotelo 1 , Miguel Ángel Meléndez Lira 1 1 Departamento de Física, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, A.P. 14740, C.P. 07300, México, Distrito Federal, México. 2 Escuela Superior de Apan, Universidad Autónoma del Estado de Hidalgo, Calle Ejido de Chimalpa Tlalayote s/n Colonia Chimalpa, Apan Hidalgo, México. 3 Escuela Superior de Física y Matemáticas del Instituto Politécnico Nacional, Edificio 9 U.P. Adolfo López Mateos, Col. San Pedro Zacatenco, C.P. 07730 México DF, México. 4 Universidad Politécnica del Valle de México, Av. Mexiquense s/n, esquina Av. Universidad Politécnica, Col. Villa Esmeralda, C.P. 54910, Tultitlán, Estado de México. The current requirements of optimal materials for optoelectronics applications require to have some control mechanisms for the size particle distribution of materials obtained by selfassembly processes; that control could improve their application in different devices. In this work we report the synthesis of self-assembled systems produced via a sequential deposition process of SiO2/CdTe/SiO2 layers using the RF reactive sputtering techniques and its optical, electrical and structural characterization. The samples were prepared on silicon (111) p-type substrates and commercial glass. In order to control the spatial distribution and the CdTe particle size the surface defects induced by variation of the reactive atmosphere in the production of the first SiO2 layer were used. The images of transmission electron microscopy shown a distribution of nanoparticles with sizes between 10 and 15 nm. The results of X-ray diffraction confirm the presence of CdTe nanoparticles. The results of transmittance, photoluminescence and Raman spectroscopies are discussed in terms of the nanoparticles size. 448 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ THF-380 ] Electrical characterization of of selfAssembled ZnO nanoparticles embedded in a silicon oxide matrix produced by reactive RF sputtering.* C. Atzin-Mondragon 1 , R. Escobedo-Alcaraz 1 , A.P. Chavelas-González 4 , A. Hernández-Hernández 2 , L.A. Hernández-Hernández 3 , A.R. GarcíaSotelo 1 , M. Meléndez-Lira ([email protected]) 1 1 Departamento de Física, CINVESTAV-IPN, , Apdo. Postal 14-740, México, DF 07000, México 2 Escuela Superior de Apan, Universidad Autónoma del Estado de Hidalgo, Calle Ejido de Chimalpa Tlalayote S/N Col. Chimalpa, Apan, Hidalgo. México 3 Escuela Superior de Física y Matemáticas del Instituto Politécnico Nacional, Edificio 9 U.P. Adolfo López Mateos, Col. San Pedro Zacatenco, C.P. 07730 México DF, México 4 Universidad Politécnica del Valle de México, Av. Mexiquense s/n, esquina Av. Universidad Politécnica, Col. Villa Esmeralda, C.P. 54910, Tultitlán, Estado de Silicon dioxide and metallic Zn films were deposited employing silicon and zinc targets. An oxygen rich working plasma was employed. A sequential deposition of SiO2/Zn/SiO2 films were deposited ; SiO2 layer was produced at 400 °C while deposition temperature of Zn layer was changed between 100 and 500 °C. The electrical transport properties were characterized by the Van deer Paw technique, IvsV and spectral response. Results indicated the formation of ZnO nanoparticles with a dependence on the Zn growth temperature. *: Partially funded by CONACyT-Mexico 449 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ THF-396 ] Synthesis and characterization of CeO2, La2O3 and codeposit thin films by RF magnetron sputtering on AA6082 aluminium alloy Silvia Beatriz Brachetti-Sibaja 1 , Silvia Beatriz Brachetti-Sibaja ([email protected]) 2 , Sandra Rodil 3 , Miguel Antonio DomínguezCrespo ([email protected]) 1 , Aidé Minerva Torres-Huerta 1 , Eugenio Rodríguez 1 1 IPN, Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada-Unidad Altamira. Km 14.5 Carr. Tampico-Pto. Industrial Altamira, Altamira Tamps. C.P. 89600. 2 TecNM, Instituto Tecnológico de Cd. Madero. Ave. Primero de Mayo s/n Col. Los Mangos Cd. Madero Tamps. C.P. 89440. 3 UNAM, Instituto de Investigaciones en Materiales, Circuito Exterior s/n C.U. Coyoacán, C.P. 04510, México D.F. In spite of the high potential applications of rare earth thin films, only few studies have been made to prepare them by radio frequency magnetron sputtering as anticorrosive protector. In the present work, cerium and lanthanum oxide films were co-deposited by r.f. magnetron sputtering from a CeO2 and La2O3 target in an argon atmosphere (20 mTorr). The films were deposited onto Si(100), glass and AA6082 aluminum alloy substrates. Two different RFpowers were tested (60 and 90 watts) and for each power, the deposition time was changed from 25, 40 and 60 minutes, as well as the substrate temperature (ambient and 200°C). The structure, morphology and chemical composition was studied by X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), and Scanning Electron Microscopy (SEM), respectively. The thickness of the thin films was obtained by ellipsometry spectroscopy. The protective character was evaluated on the aluminum alloy substrate by Open Circuit Potential (OCP), Polarization Resistant (Rp), Electrochemical Impedance Spectroscopy (EIS) and Potentiodynamic Polarization Curves. Electrochemical evaluated indicated that the rare earth films behave as cathodic inhibitors. The lanthanum oxide thin films are more protective as cerium oxide probably because is very reactive in contact of atmosphere, producing La(OH)3 with a corrosion velocity of 546.0 x 10-6 mpy (1.39 x 10-5 mmpy). Acknowledgements to CONACYT CB-2009, SIP 2015-0202, 2015-0227 and PAPIIT 103910. 450 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ THF-405 ] Structural and optical properties of TiO2 thin films deposited by laser ablation under ambient air M. M. Barajas-Carrillo 2 , A. Pérez-Centeno 1 , G. Gómez-Rosas 1 , M. A. Santana-Aranda 1 , J. G. Quiñones-Galván ([email protected]) 1 1 2 Departamento de Física, CUCEI, Universidad de Guadalajara Licenciatura Ingeniería en Comunicaciones y Electrónica, CUCEI, Universidad de Guadalajara Thin films of TiO2 were deposited by laser ablation. High purity Ti and compressed TiO2 powders were used as target materials. Two samples were deposited from each target at different laser fluence values in order to get low and high mean kinetic energies of the Ti ions in the plasma. The deposition chamber was initially heated and evacuated to a background pressure of 10-6 Torr to eliminate water traces in the chamber. The working pressure was kept constant at 10-3 Torr of ambient air for all the experiments. Two additional samples were deposited from TiO2 target in vacuum (10-6 Torr) with the aim of evaluate oxygen loss during the ablation process. The optical and structural properties of the films were studied as a function of the target and laser fluence. Acknowledgements: Authors want to thank the technical support of Sergio Oliva. This work was partially supported by CONACyT (grant CB2010-156773) and U. de G. (programs proSNI and PROINPEP). 451 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ THF-421 ] Operation of Extended-Gate ISFETs Employing a Thin-Layer of ALD Al2O3 as the Sensitive Dielectric Berni Manolo Perez Ramos ([email protected]) 1 , Joel Molina Reyes 1 1 Departamento de Electrónica, Instituto Nacional de Astrofísica, Óptica y Electrónica, Luis Enrique Erro 1, Tonantzintla, Puebla, México, 72000 One of the major advantages of solid state sensors is the possibility to integrate them in a chip along with control, signal processing and conditioning circuitry. However, there are still some difficulties with the integration of ion sensors due that these devices usually operates immersed in chemical solutions. Additionally, the materials employed in the fabrication of chemical sensors must be selected in such a way that the sensitivity is maximized and, at the same time, the compatibility of the fabrication process is maintained. For these reasons, this work presents the operation of Extended-Gate ISFETs (EG-ISFET) fabricated with a conventional CMOS process (MOSIS 0.5 um). The extended gates were obtained by using the top metal layer as sensing layers, connected to the polysilicon gate of a conventional FET. The sensors were then covered by a thin-film of Atomic Layer Deposited (ALD) Al2O3 used as the sensitive dielectric, and at the same time providing an additional passivation layer to protect the electrically active areas of the chip. It is shown that these sensors operate with an almost ideal Nernstian sensitivity to pH changes. Besides, the compatibility of the fabrication of chemical sensors with a conventional CMOS process and the application of ALD dielectrics as sensitive layers is fully demonstrated. 452 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ THF-430 ] Optical and structural properties of gan grown by sublimation into tube furnace Luis Alberto Hernández-Hernández ([email protected]) 2 , Gerardo Contreras-Puente 2 , Francisco de Moure-Flores 4 , Jorge AguilarHernández 2 , Osvaldo de Melo-Pereira 3 , Karla Gutiérrez-Z-B 2 , Máximo López-López 1 , Guillermo Santana-Rodríguez 5 1 Departamento de Física, Centro de Investigación y de Estudios Avanzados - I.P.N., C.P.07360 México, D.F. 2 Escuela Superior de Física y Matemáticas – Instituto Politécnico Nacional, Edificio No. 9, U.P.A.L.M., San Pedro Zacatenco, C.P. 07738 México D.F. 3 Facultad de Física de la Universidad de La Habana, Colina Universitaria, 10400, La Habana, Cuba 4 Facultad de Química, Universidad Autónoma de Querétaro, Querétaro C.P. 09790 México 5 Instituto de Investigación en Materiales Universidad Nacional Autónoma de México, Coyoacan, C.P. 04510 México D.F. We report in this work the structural and optical properties of GaN films grown by sublimation employing a tube furnace without any additional source of nitrogen during the process. The samples were deposited on p-type silicon (1 1 1) substrates using GaN powder (99.999% purity) as material source.The GaN powder as well as the substrate were contained inside a semi-hermetic cell made of graphite at ambient atmosphere. Structural and optical characterization obtained through X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS) and Photoluminescence (PL) measurements are presented. XRD diffractograms exhibit the growth of policrystalline hexagonal GaN. Concerning EDS measurements they shows the presence of stoichiometric GaN. Finally, PL measurements under UV excitation (He:Cd laser λ=325 nm) confirm the emission at room temperature. A deeply discussion of the results are presented and discussed. †The authors acknowledge financial support for this work from FONDO SECTORIAL CONACYT-SENER-SUSTENTABILIDAD ENERGÉTICA through CeMIE-sol, within of the strategic project number 37; “Development of new photovoltaic devices and semisuperconductor materials”. 453 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ THF-460 ] Effect of sputtering parameters in the properties of TiO2 and TiN thin films Andrés González-Hernández ([email protected]) 1 , Andrés González-Hernández 2 , Miguel Antonio Domínguez-Crespo ([email protected]) 1 , Tomás LozanoRamírez 2 , Deyanira Del Ángel-López 1 , Aidé Minerva Torres-Huerta 1 , Silvia Beatriz Brachetti-Sibaja 2 1 IPN, Centro de Investigación en Ciencia Aplicada y Tecnología Avanzada, Unidad Altamira. Km 14.5 Carr Tampico-Pto Industrial Altamira, Altamira Tamps. C.P. 89600 2 TecNM, InstitutoTecnológico de Cd. Madero. Ave. Primero de Mayo s/n Col. Los Mangos Cd. Madero Tamps. C.P. 89440 The titanium oxide (TiO2) thin films have been investigated in recent years for their interesting properties. It has a wide range of applications like antireflection and protective coatings, gas and humidity sensors, solar energy converters among others. The TiO2 has three crystalline structures, brookite (orthorhombic), anatase and rutile (tetragonal) each phase has characteristic properties that make them desirable for specific applications. On the other hand, the titanium nitride (TiN) is an extremely hard ceramic material and has been used in the form of thin films to increase hardness in cutting tools and as non-toxic exterior for medical implants, its crystalline phases are face centered cubic δ(TiN) and hexagonal ε(Ti2N). Both titanium thin films can be obtained by sputttering deposition, a process whereby atoms are ejected from a solid target material due to bombardment of the target by energetic particles. All the properties of these thin films can be affected by the synthesis parameters. In the present work, TiO2 and TiN films were deposited by radiofrequency magnetron sputtering (RF-magnetron sputtering) using a titanium target in glass and steel AISI 1065 substrates, respectively. The sputtering parameters of time (15 - 120 min), RFpower (100 - 200 watts), working distance (11 - 17 cm), the flow rate of Ar for TiO2 and the gas ratio of Ar/N2 for TiN were changed, to obtain different thin films and after the deposition were thermal treated to different temperatures in a range of 200 - 400 °C. The XRD patterns of TiO2 obtained with 200 watts, 120 min and 300 °C; showed the structure of anatase phase that is characterized by films color steely glint, this phase has semiconductor characteristics and is used in photocatalyst applications. The TiN films color varies strongly with the composition; in the TiN films obtained with a working distance of 17 cm, 160 watts and 150 min results in thin films color gold characteristic of the TiN. However, with major power (200 watts), the films were color blue and using a power of 100 watts the thin films were color purple, the coloration was influenced by the Ar/N2 gas ratio, the working distance and the RF-power, this can be due to the kinetic energy generated in the plasma during the collision impact of argon ions and titanium causes mixes with small amounts of oxygen generating an oxidation with sub-products like TiO2 which strongly affect the TiN properties like hardness and adhesion. 454 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ THF-463 ] Comparative study of ZnO thin films prepared by PLD using nanoparticles ZnO mixed in a cyanoacrylate target and ceramic target Enrique Josué Chan y Díaz ([email protected]) 1 , Román Ernesto Castro Rodríguez ([email protected]) 2 1 Departamento de Ingeniería Mecánica, Instituto Tecnológico de Mérida, Av. Tecnológico km. 4.5 S/N, 97118, Mérida, Yucatán, México. 2 Department of Applied Physics, CINVESTAV-IPN, Unidad Mérida. 97310 Mérida Yucatán, México. ZnO thin films were deposited on ITO substrates using the Nd:YAG-laser ablation method and a target made up of powder nanoparticles with a size of less than 100 nm mixed with cyanoacrylate glue (composite target). In this study, the structural and optical properties of the ZnO thin films deposited using this target compared to those of the ZnO thin films deposited using a traditional target made up of sintered powder (sintered target) were examined. The ZnO thin films deposited using the composite target at substrate temperature of 300 ºC were polycrystalline with preferential orientations in the planes (100) and (101), grain size of ~40 nm, in the visible range and showed a high resistivity of ~1.30×102 Ω-cm, indicating that these films showed more enhanced properties than the ZnO thin film deposited using sintered target, this allows the thin films obtained by the former target to be used as buffer and anti-reflective layer in solar cells based in CdTe. The enhanced properties of the ZnO thin film prepared with composite target were considered to be caused by the notable improvement in packing density and high transmittance over an average of 85% surface roughness, which were observed from atomic force microscopy (AFM) images due to the composite target consisting of nanoparticles embedded into a matrix of cyanoacrylate glue. Keywords: ZnO thin film, PLD, cianoacrylate, ZnO buffer layer, ZnO anti-reflecting. This work has been supported under Project No. CB/1012/178748 CONACYT/México 455 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ THF-466 ] influence of the cr incorporation on the structure of sputtered ZrN films deposited at low temperatures A. M. Villegas Mercado 3 , A. Esparza Hernández 3 , J. J. Ortega ([email protected]) 3 , F. Puch Ceballos 3 , R. Escobedo-Galindo 2 , C. Falcony 1 , J. J. Araiza 3 1 CINVESTAV, IPN, Distrito Federal, México. 2 ICMM, CSIC, Madrid, España 3 Unidad Académica de Física, UAZ, Zacatecas, México. We have studied the influence of the Cr incorporation in the crystalline structure of ZrN thin films deposited by DC magnetron co-sputtering processes at low temperature. The amount of the chromium in the films depends directly on the power applied to the chromium cathode during the deposition. Energy Dispersive X-Ray (EDX) analysis and X-ray Diffraction (XRD) analyzed the chemical composition and the crystalline structure of the films, respectively. Steel sheets and crystalline (100) Silicon wafers were used as substrates. When Cr atoms are incorporated into the ZrN coatings, the strong ZrN (200) preferred orientation is modified to a combination of phases such as ZrN (111), Zr3N4 (211). FTIR (Fourier Transform Infrared Spectroscopy) allowed us to complete the identification of the nitrides and oxides incorporated into the deposited films. 456 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ THF-472 ] Piezoresistive Sensor Made of Graphite Films Deposited by Direct Friction Renan Gabbi 1 , Graciane Hammes 1 , Geferson Gustavo Wagner Mota da Silva 1 , Luciane Scarton 1 , Luiz Antonio Rasia 3 , Antonio Carlos Valdiero 2 , André Luciano Rakowiski 1 1 Unijuí / DCEEng - Department of Science and Engineering, Lulu Ingelfritz Street, 480, Ijuí, Brazil 2 Unijuí / DCEEng - Department of Science and Engineering, Rudi Franke Avenue, 540, Panambi, Brazil 3 Unijuí / DCEEng - Department of Science and Engineering, Sao Francisco Street, 501, Ijuí, Brazil Flexible electronic devices can be produced by depositing single or multiple layers of functional materials, such as conductive, resistive, semi-conductive or dielectric inks, onto a flexible substrate.Today, the application of some of these materials is being performed by high cost, small capacity processes such as physical and chemical vapor deposition, sputtering and spin coating. In this paper we use graphite pencil lines of different hardness and lengths and widths controlled on polyester substrates and paper and build a sensor to mechanical stress. The devices were manufactured by drawing a line 0.5 cm wide and 6 cm long. Contacts were made using conductive silver ink and the electrical resistance was measured. Resistivity measurements, film thickness and the number of atoms in the deposited layer were estimated through indirect methods. The deposition friction graphite on flexible substrates made possible to identify the main characteristics of the film at a relatively low cost, compared with traditional deposition methods. The results obtained allowed to extract, through mathematical models, the sensitivity factor and the cross effects of electrical, mechanical and thermal properties of these films have been used as piezoresistor. 457 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ THF-483 ] effects of annealing temperature on cosputtered P type ZnO:Ag,N thin films S. F. Ocón Trejo 2 , L. A. Sandoval Vázquez 2 , J. J. Ortega ([email protected]) 2 , M. L. Pérez Arrieta 2 , C. Falcony 1 , J. J. Araiza 2 1 2 CINVESTAV, IPN, Distrito Federal, México. Unidad Académica de Física, UAZ, Zacatecas, México. Ag and N dual acceptor doped ZnO thin films were deposited on GaAs (100) substrates by DC reactive magnetron co-sputtering at room temperature and nitrogen/oxygen reactive atmosphere. After growth, the samples were annealed at 300°C and 400°C for 1 hr in a nitrogen atmosphere. The thermic treatment improved the crystalline structure of the ZnO:Ag,N thin films, the annealed films showed three well defined peaks at 31.62, 34.24, and 36.12 degrees, that correspond to the (100), (002) and (101) planes of wurtzite structure for hexagonal ZnO respectively. The electrical properties were explored by Hall Effect measurement. After annealing treatment the films presented p-type conductivity with hole concentration greater than 1016 cm-3 [ THF-492 ] post annealing influence on properties of InN codoped ZnO thin films F. Avelar Muñoz 3 , J. J. Ortega ([email protected]) 3 , J. Ortiz Saavedra 3 , V. H. Méndez García 1 , C. Falcony 2 , J. J. Araiza 3 1 CIACyT, UASLP, San Luis Potosí, México CINVESTAV, IPN, Distrito Federal, México. 3 Unidad Académica de Física, UAZ, Zacatecas, México. 2 DC reactive co-sputtered p-type ZnO:In-N thin films were deposited at room temperature using a reactive atmosphere of nitrogen and oxygen at different concentrations. After growth, the samples were annealed at 300°C for 1 hr in a nitrogen atmosphere. The crystalline structure was determined by XRD, as deposited films were practically amorphous, however after heat treatment the films showed the typical hexagonal structure of ZnO. As deposited films presented n-type characteristics, however, the electrical conductivity showed a transition from n-type to p type for the films treated at 300°C, in all cases the hole concentrations are lesser than 1016 cm-3. The transparency of the films were gradually reduced as the atomic percentages of nitrogen and indium were increased, concurrently, the Tauc obtained band gap was shifted to lower energies. 458 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ THF-555 ] Photoconductivity of aluminium doped ZnO thin films obtained by the sol-gel method Cristhian Alejandro Mercado-Ornelas 2 , Juan Ortiz-Saavedra 2 , Jose de Jésus Araiza-Ibarra 2 , Felipe Puch-Ceballos 2 , Leticia Pérez-Arrieta 2 , José Guadalupe Quiñones-Galván 1 , H. Tototzintle-Huitle ([email protected]) 2 1 Departamento de Física, Centro Universitario de Ciencias Exactas e Ingenierías, Universidad de Guadalajara, Guadalajara, México. 2 Unidad Académica de Física, Universidad Autónoma de Zacatecas, Zacatecas, México. ZnO materials are of great interest for their optical, structural, electrical and photoconductivity properties and also by their chemical stability which are essential aspects for many possible applications, e.g. as transparent electrodes and windows in solar cells, in gas sensors, and as photocatalytic agents. In ZnO:Al, photoresponse show a slow conduction decay process, wich is controlled by surface effects such as gas adsorption and desorption. Consequently, the decay of photoconduction is strongly dependent on the ambient gas conditions. In this work, we describe the room temperature photoconductivity of thin films of aluminium doped zinc oxide prepared by the sol-gel technique on silica glass substrates. The starting solutions were prepared using zinc acetate as precursor, diethylene glycol as organic template, methanol as solvents, triethylamine as chelating agent and aluminium nitrate as dopant. The Zn molar concentration of the solutions used to obtain the thin films were 1.3 M. The content of aluminium in the precursor solution is refered as the atomic porcentage with respect to Zinc. Here, we used [Al]/[Zn]= 1,3 ,5,7 ,9 % at. The films obtained where thermally treated in air at 500°C. The samples were characterized by XRD, EDS, UVVis and IR spectroscopies. Van Der Paw measurements were used to investigate the electrical and photoelectrical properties in various ambient atmosphere. The dark conductivity of the films decreased with decreasing film thickness while the conductivity under illumination was almost constant and was in the range of 10-2 to 101 Scm irrespective of the film thickness. 459 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla TRIBOLOGY (TRB) Chairman: Joaquin Oseguera Peña (ITESM) Sesión Oral [ TRB-22 ] Mechanical and tribological performance of red clay ceramic tiles coated with flay ash powders by thermal spraying technique. Gabriel Peña-Rodríguez ([email protected]) 1 , Jaime Dulce-Moreno 1 , Jessica Daza 2 , Silvia Orozco 2 , Fabio Vargas-Galvis 3 1 Department of Physics. Group GITEC Francisco de Paula Santander University 2 Industrial Engineering. Francisco de Paula Santander University 3 Research group pyrometallurgical and Materials (GIPIMME), University of Antioquia The mechanical and tribological performance of red clay ceramic tiles uncoated and coated by oxyfuel thermal spraying process from flay ash powders was evaluated. The ceramic tile substrates were manufactured by uniaxial pressing at 26.17 bar pressure, and sintered at 1100 °C. The coating thickness was determined based on the number of projection-cycles oxyacetylene flame over substrate. The structure was studied using X-ray diffraction (XRD, Bruker D8 Advance) and scanning electron microscopy (SEM, FEI Quanta 650 FG); the mechanical resistance to bending and wear by abrasion deep, were studied using NTC standards 4321-4 and 4321-6 respectively; adhesion was measured using Elcometer equipment Type III according to ASTM D-4541-02 and the average roughness (Ra) was found according to ASTM standard D7127-13, using the profilometer Mitutoyo SJ 201. The surface morphology presented the heterogeneous molten or semi molten splats with good adhesion, justifying increased mechanical resistance to bending and wear by abrasion deep.These results contribute to the development of ceramic products with added value, to be used in various technological applications. 460 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ TRB-51 ] Tribological evaluation of hydrogenated DLC coating deposited on carbon steel José Solis Romero ([email protected]) 1 , Oscar Hernández Gómez 1 , Luis Tranquilino 1 , Víctor Augusto Castellanos Escamilla 1 , Oscar armando Gómez Vargas 1 1 SEP/SES/TecNM/IT de Tlalnepantla. Av. Mario Colin S/N, Tlalnepantla de Baz, Edo. de Méx. CP 54070 In oil and gas companies many components are subjected to wear and corrosive environments. The development of protective coatings on these parts is of high interest to preserve its structural integrity. The chemical stability of diamond-like carbon (DLC) coatings seems to be good candidates for corrosion protection in addition to their wear resistance for using in pipelines equipment, such as subsea check valves, pistons and pumps. The aim of this study is to evaluate the tribological performances of a hydrogenated DLC coating. The coating was deposited on API X65 carbon steel using plasma enhanced chemical vapour deposition technology (PECVD). Characterization of the films was carried out by means of Nano-indentation, surface roughness, calotest, Raman spectroscopy, atomic force microscopy, and scanning electron microscopy. Tribological analysis was done in terms of wear tests under continuous and reciprocating sliding with maximum initial Hertzian stress of 150 and 400 MPa under dry condition. The Hydrogenated DLC film provided a good improvement on the integrity against corrosion on carbon steel due to the positive results in relation to wear tests. 461 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ TRB-125 ] Tribology of Nanocomposite coatings in Methane Environment Giovanni Ramirez ([email protected]) 1 , Osman L. Eryilmaz 1 , Osmary Depablos 2 , Roberto Mirabal 2 , Yifeng Liao 1 , Sandra E. Rodil 2 , Ali Erdemir 1 1 2 Energy Systems Division, Argonne National Laboratory, Argonne, IL 60439, USA Instituto de Investigaciones en Materiales, Universidad Nacional Autonoma de Mexico, Mexico City, Mexico Different nanocomoposite coatings based on metallic nitrides (V/Mo) and catalytically active metals (Cu/Ni) were prepared using a high impulse magnetron sputtering (HIPIMS) system. The content of the segregated phases of the nanocomposite films was optimized using the power ratio between the different metallic targets during coating preparation. The coatings were deposited on AISI 52100 steel substrates which were previously subjected to ion etching using HIPIMS. The tribological tests were performed in a ball-on-disk test machine under 900 mBar of methane gas pressure. The coated pairs (ball and disk) were compared with the uncoated pairs of 52100 steel. The nanocomposite coatings were able to reduce friction by as much as 40% in comparison with the uncoated steel samples. Most importantly, the wear of the nanocomposite surfaces was reduced dramatically to an unmeasurable level. The chemical composition, structural morphology and microstructure of the coatings were studied by X-ray photo electron spectroscopy, scanning electron microscopy, and X-ray diffraction. The superior tribological performance of the nanocomposite coatings in methane environment was studied using Confocal Raman in order to elucidate the chemical nature of tribochemical interactions and hence the plausible mechanisms responsible for extraordinary wear performance. 462 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ TRB-152 ] Tribological performance of 316L AND 316L TiN coated against uhmw pe and uhmw pe mediacal grade for orthopaedic joint implants Alejandro Peña Bautista ([email protected]) 1 , Joaquín Esteban Oseguera Peña 2 , Dulce Viridiana Melo Máximo 1 , Rafael Carrera Espinoza 1 1 2 Instituto Tecnológico y de Estudios Superiores de Monterrey, CEM Instituto Tecnológico y de Estudios Superiores deMonterrey, CEM An excellent tribological couple for orthopaedic joint implants preferably will include a metallic component articulating as 316L against a polymer component ultra-high molecular weight polyeltilene (UHMW PE). However, the accelerated wear of UHMW PE in bearing surfaces produces debris principally and cause high wear and high coefficient friction. In order to improve the performance of tribological biomaterials pair a PVD TiN coating was deposited on 316L surface; in addition UHMW PE underwent treatment of gamma radiation for transform it to medical grade. 316L, TiN, UHMW PE and UHMW PE medical grade biomaterials were characterized (Ra, H, E, SEM); also thickness and XRD were characterized for PVD TiN. A series of three wear test were made on pin on disc tribometer considering the following tribological pair of materials: 316L against UHMW PE; 316L against UHMW PE medical grade; 316L PVD TiN coated against UHMW PE and 316L PVD TiN coated against UHMW PE medical grade at wear conditions: 5, 10 and 15 N of applied load, 0.05 m/s of sliding speed, 1000 m of sliding distance and distilled water lubricated condition. UHMW PE and UHMW PE medical grade shows high wear meanwhile 316L and 316L PVD TiN coated materials they almost did no wear (negligible). Different values of wear rate and friction coefficient were obtained; considering 5, 10 and 15 N of applied loads, the best wear pair (lowest wear and friction coefficient) it was to 316L against UHMW PE medical grade and the worse wear pair (highest wear and friction coefficient) it was to 316L PVD TiN coated against UHMW PE medical grade. Keywords: Wear, friction coefficient, PVD TiN coating, UHMW PE 463 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ TRB-227 ] Comparison of the tribological behavior of an AISI 1538MV steel: surface laser quenching versus conventional quenching & tempering treatment. Rafael Carrera Espinoza ([email protected]) 2,5 , Ulises Figueroa López ([email protected]) 3 , Alejandro Rojo Valerio 1 , Joaquin del Prado Villasana 4 1 Centro de investigación de Mecatrónica Automotriz, ITESM Campus Toluca, Eduardo Monroy Cárdenas 2000, San Antonio Buenavista, 50110 Toluca de Lerdo, Méx. 2 Escuela Nacional de Posgrado, ITESM Campus Estado de México, Carr. Lago de Guadalupe Km. 3.5, Margarita Maza de Juárez, 52926 Atizapán de Zaragoza, Méx. 3 Ingeniería Mecánica y Mecatrónica y Escuela Nacional de Posgrado, ITESM Campus Estado de México, Carr. Lago de Guadalupe Km. 3.5, Margarita Maza de Juárez, 52926 Atizapán de Zaragoza, Méx. 4 Investigación Desarrollo e Innovación, ITESM Campus Toluca, Eduardo Monroy Cárdenas 2000, San Antonio Buenavista, 50110 Toluca de Lerdo, Méx. 5 Posgrado, ITSPR, Calle Luis Donaldo Colosio Murrieta S/N, Arroyo del Maíz, 93230 Poza Rica de Hidalgo, Ver. This paper compares the tribological behavior of an AISI 1538MV steel that was heat treated by two technologies: surface laser quenching and a conventional quenching and tempering treatment. Sliding wear tests were carried out by the pin-on disc method. A 5 mm diameter WC ball and 56.2 mm diameter and 5 mm thick disks were used as a tribo-pair. The worn surfaces on the disks and the ball were evaluated by SEM and MO, respectively, for to identify the wear mechanisms. The coefficient of friction (CoF) for the tribo-pair in the laser quenched samples were slightly lower than the values obtained for the conventional treated ones. A similar behavior was found for the wear rate. Laser quenching offers a similar tribological performance than conventional quenching and tempering, and therefore, it is possible to use one or other, depending on the application and the available technology. 464 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ TRB-556 ] Tribological Challenges in Micromachines Esteban Broitman ([email protected]) 1 1 IFM, Linkoping University, SE58183 Linkoping, Sweden Micromachines are mechanical devices with designed sizes in the range 100 nm to 100 µm, and usually fabricated with semiconductor technologies to integrate mechanical components with electronics on a single chip. Known also as MEMS (micro-electro-mechanical systems), present industrial applications include accelerometers in automotive systems, inkjet printer heads, game controllers, and rotation sensors for smartphones. Most of commercial micromachines are designed as transducers for applications with no contact or sliding: they are either sensors or actuators. Despite of niche industrial applications with designs of more complex MEMS devices containing moving mechanical assemblies (MEMS-MMA) like micromotors, gears and levers, the commercial production of these kind of micromachines is inexistent. The main problem in micromachines is tribological: the presence of stiction, high friction and wear between the small components. Adhesion at the microscale is a consequence of van der Waals forces: electrostatic interactions between surface dipoles and charges, as well as capillary phenomena and chemical forces. Friction and wear are inevitable in mechanisms where components in contact have relative motion. Friction become increasingly significant as the system size shrinks and it is a crucial factor that determines not only efficiency but durability. Therefore, it becomes critical on the microscale and is one of the fundamental limitations in the design of reliable micromotors, microgenerators, and microengines. Lubrication for decreasing friction and wear in these devices is difficult, because capillary forces created by confining liquids to small geometries is in the same order of magnitude as actuation forces generated by micromachines. Therefore, only solid or vapor-phase lubrication can be used. However, there are some applications like stepper motors taking advantage of friction: with step sizes on the order of 10 to 100 nm, and actuation forces in the milli-Newton scale, they could be used for positioning optical, data storage, and medical applications. This work focuses on the main tribological challenges of micromachines. The characterization of multi-length-scale tribological phenomena will be reviewed. Basic silicon mechanical and tribological properties and micromachining methods are reviewed. Solid lubrication by depositing carbon-based coatings using thin film technology, and liquid lubricants applied by vapor-phase lubrication are discussed. Potential improvements and economic feasibility issues are also addressed. 465 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla Sesión Poster [ TRB-9 ] TRIBOCORROSION BEHAVIOUR OF Nb/NbN FILMS Erika Ruiz ([email protected]) 1 , Wiliiam Aperador 1 1 School of Engineering, Universidad Militar Nueva Granada, Bogotá-Colombia Niobium Nitride a coating has been studied for its superconducting properties, hardness, wear resistance to corrosion; furthermore improve corrosion resistance and wear on the coated steel surface. Regarding, its chemical properties is characterized by a high melting point and low resistivity; with this study was performed the evaluating of the NbN thin films with an intermediate layer of Nb on substrates of AISI 316LVM stainless steel, deposited by physical vapor deposition technique in order to evaluate the effect of the bias voltage in the process deposition, on the degradation rate, tribological properties and system triboelectrochemistry. The tribological tests were performed with a bone pin and the corrosion resistance was evaluated by testing the impedance electrochemical spectroscopy and Tafel polarization curves, the electrolytic medium was Hank's solution. It was found that the electrochemical parameters decrease with increasing bias voltage. The friction coefficient decreases in comparison with the substrate and the wear in the synergistic system between mechanical wear and electrochemical indicates that is lower when the evaluation is carried out in a simulated biological fluid. 466 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ TRB-53 ] Electrochemical and tribological assessing of WC-DLC coating deposited on API X65 carbon steel José Solis Romero ([email protected]) 2 , Joaquín Oseguera Peña 1 , Víctor Augusto Castellanos Escamilla 2 , Miguel Angel Paredes Rueda 2 , Oscar Armando Gómez Vargas 2 , Rodolfo Velázquez Mancilla 2 1 Departamento de Mecatrónica, Instituto Tecnológico y de Estudios Superiores de Monterrey, Campus Estado de México, Carretera al Lago de Guadalupe km 3.5, Atizapán 52926, México. 2 SEP/SES/TecNM/IT de Tlalnepantla, Div. de Posgrado. Av. Mario Colin S/N, Tlalnepantla Edo. de Méx. CP 54070. México. In many industrial applications components are submitted to wear and corrosive environments. The development of protective coatings on these parts is of high interest to preserve its structural integrity. The chemical stability of diamond-like carbon (DLC) coatings seems to be a respectable candidate for corrosion and wear to protect pipelines equipment, such as subsea check valves, pistons and pumps. The aim of this study is to evaluate the electrochemical and tribological behaviour of WC-DLC coatings deposited on API X65 carbon steel using plasma enhanced chemical vapour deposition technology. The characterization of the film was carried out by means of Nano-indentation, surface roughness, calotest, Raman spectroscopy, atomic force microscopy and scanning electron microscopy. The applicability of these two types of coatings for corrosive protection was proved by means of the electrochemical tests and electrochemical impedance. The tribological analysis were done in terms of wear tests under reciprocating sliding with maximum initial Hertzian stress of 150 and 400 MPa under dry and wet conditions. The electrochemical assesment was done on the surface of DLC films before and after wear tests in order to verify if the corrosion process of the carbon steel substrate into the wear defects could affect the adhesion of the coating. Although no defects were observed on the hydrogenated DLC after wear tests (contact pressure of 150 MPa), the electrochemical tests showed an increase on the anodic current densities with these samples in relation to samples that were not subjected to wear tests. It means that 150 MPa was sufficient to produce Nano defects on the hydrogenated DLC surface and to exposure the carbon steel substrate to the corrosive solution. The hydrogenated DLC film provided a good improvement on the integrity against corrosion on carbon steel due to the positive results in relation to wear tests. Furthermore, it was evidenced a protective barrier, a reduced pitting corrosion on the carbon steel bulk because of the same OCPs, as it had high resistivity based on the lowest anodic current densities. In addition, the results showed that the resistance of the film, applied over carbon steel had excellent performance in situations where the equipment is subjected to conditions of wear and corrosion acting together in saline environments. 467 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ TRB-54 ] Micro-abrasive wear of dynamic seals Leonardo Israel Farfán-Cabrera ([email protected]) 1 , Ezequiel Alberto Gallardo-Hernández 1 1 IPN, SEPI-ESIME Zacatenco, Grupo de Tribología, Col. Lindavista 07738, Mexico D. F. Dynamic seals are devices utilized to prevent or limit fluid leakages in machinery. Abrasive wear of seal lips is majorly produced by micro-particles (wear debris) deposited as contaminants in the fluid involved. In this study, a TE 66 Micro-Scale Abrasion Tester was used to simulate the micro-abrasive wear occurred. A Nitrile lip seal has been selected and examined. The abrasive agent was made of distilled water and SiC micro-particles. Wear results are showed at four different loads and various sliding distances. In addition, Scanning Electron Microscopy and Laser Scanning Confocal Microscopy were used towards detecting and obtaining the wear scar topographies and their measurements. In conclusion, this method could be suitable to study the three-body abrasion occurred in elastomeric materials for dynamic seal applications. 468 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ TRB-71 ] Modelling micro-scale abrasion of duplextreated steels José Guadalupe Mata Maldonado ([email protected]) 1 , Rafael David Mercado Solís 1 1 Universidad Autónoma de Nuevo León This paper presents details of a geometrical model of micro-scale abrasion of duplex-treated steels based on the calotte-grinding test and Archard’s wear equation. In the computations, the model calculates the individual wear coefficients of coating and substrate as a function of either: (i) the outer calotte diameter and the coating thickness, (ii) the inner calotte diameter and the coating thickness, or (iii) the outer diameter and the ratio between inner and outer diameters. In practice the first two calculations are advantageous because coating thickness is generally known beforehand, thus, the measurement of only one diameter is needed. However, a better insight into the micro-abrasive wear process may be accounted for if the third approach is used because it provides a clearer separation between the extents of wear underwent by the coating and by the substrate. This is a particularly useful approach when significant differences in wear coefficients for the coating and the substrate are expected. The proposed model was validated by a series of calotte-grinding experiments using a 30 mm diameter steel ball rotating against duplex-treated (ion nitrided + PVD coated) AISI H13 tool steel, coated with TiN, CrN and TiAlN by arc evaporation. Since the experimentally obtained results were in very close agreement with the predictions of the geometrical model, it is concluded that the model is a very powerful tool for micro-abrasive wear predictions in duplex-treated steels and it may be further extended to other coated systems. 469 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ TRB-369 ] Nanofrictional behavior of Y-Cr-O films with amorphous, crystalline and textured microstructures J. J. Gervacio-Arciniega 2 , Francisco J. Flores-Ruiz ([email protected]) 2 , C. J. Diliegros-Godines 2 , E. Broitman 3 , C. I. Enriquez-Flores 1 , F. J. Espinoza-Beltrán 1 , J. Siqueiros 2 , M. P. Cruz 2 1 CINVESTAV Unidad Querétaro, Lib. Norponiente 2000, Real de Juriquilla, 76230 Querétaro, Qro. México. 2 CNyN-UNAM, km. 107, Carretera Tijuana-Ensenada 22860, Ensenada, B.C., México. 3 Thin Film Physics Division, IFM, Linköping University, SE-58183 Linköping, Sweden Differences in friction coefficient (µ) of magnetoelectric textured and polycrystalline YCrO3 and non-magnetoelectric Y-Cr-O amorphous films are analyzed. The friction coefficient was evaluated by atomic force microscopy using a simple quantitative procedure where the dependence of friction force with the applied load is obtained in only one topography image. A simple code was developed with the MATLAB® software to analyze the experimental data. The code includes a correction the hysteresis in the forward and backward directions. The quantification of load exerted on the sample surface was obtained by finite element analysis starting from experimental dynamic information. The result showed that polycrystalline films have a friction coefficient (~0.1) similar to those with amorphous structure while the textured films grown on epitaxial substrate has the highest µ (~0.5). From a viewpoint of industrial application, where the recording of ferroelectric memories is mechanically achieved pressing AFM tips against the surface, YCrO3 films grown on non-epitaxial substrate seem to be the better candidates due to their lower µ. 470 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ TRB-470 ] Physical and tribological properties of reactively co-sputtered Niobium Zirconium Nitride K. C. Luna Sandoval 4 , J. J. Ortega ([email protected]) 4 , H. Tototzintle Huitle 4 , J. G. Quiñones Galván 2 , C. Falcony 1 , R. Escobedo Galindo 3 , J.J. Araiza 4 1 CINVESTAV, IPN, Distrito Federal, México. 2 CUCEI, UDG, Jalisco, México. 3 ICMM, CSIC, Madrid, España 4 Unidad Académica de Física, UAZ, Zacatecas, México. In this work are reported on the physical and tribological properties of reactively sputtered niobium zirconium nitride deposited on steel sheets and crystalline (100) silicon wafers as substrates using Nb and Zr targets. These films were grown using a fixed power to the Zr target (70 W), but with a variable power to the Nb target. The chemical composition was obtained from EDX measurements. X-ray diffraction revealed that a two-phase nanocomposite material was formed. The nanocomposite consisted of nanocrystals of (Nb, Zr)N, embedded in an amorphous matrix. The optical constants were measured using spectral ellipsometry and were simulated using a Drude-Lorentz model. The hardness and elastic modulus values were measured by nanoindentation and were correlated to the microstructure of the films. 471 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla Science Divulgation (SCD) Chairman: Wilfrido Calleja (INAOE) Sesión Oral [ SCD-256 ] El método de valoración contingente en el manejo de residuos peligrosos de la región Cuitzeo, Michoacán María Liliana Ávalos Rodríguez ([email protected]) 1 , Jorge Víctor Alcaraz Vera 1 1 Universidad Michoacana de San Nicolás de Hidalgo Los cambios en la producción y productividad del siglo XIX han dado la pauta para analizar los efectos al ambiente y sociedad, uno de esos efectos ha sido la generación de residuos que independientemente de sus características representan un peligro. Por ello diversos estudios muestran que se puede valorar económicamente su manejo y generación; esta investigación analiza estudios que han empleado dichos métodos, destacando que la mayoría de ellos analizan la problemática de residuos urbanos (67%), el 4% abordan los residuos de manejo especial y el 39% los residuos peligrosos. Se observa que los estudios consideraron la valoración contingente, estudios hedónicos, costo de recreación, de beneficio, de viaje, de reposición, de efectividad, mitigación, análisis y morbilidad. Las principales variables observadas fueron los tipos y volúmenes de residuos, el factor riesgo, la peligrosidad, las condiciones socioeconómicas y el manejo de residuos en función del cumplimiento de las disposiciones legales en materia técnica y operativa. En materia de residuos peligrosos, los estudios sugieren que se pueden valorar a través del método de valoración contingente que pretende conocer la disponibilidad a pagar por que el manejo bajo parámetros de eficiencia sanitaria, ambiental y económica. Como resultados preliminares de la aplicación del Método de Valoración Contingente en la Región Cuitzeo, Michoacán mediante una encuesta a generadores de residuos peligrosos, se observa que el 80% está dispuestos a pagar montos que oscilan entre los $2.00 a los $4,000 pesos por gestiones y servicios técnicos, operativos y jurídicos. 472 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SCD-285 ] Hidrógeno, ¿energía del futuro? Mario Fidel García Sánchez ([email protected]) 1 1 Unidad Profesional Interdisciplinaria de Ingeniería y Tecnologías Avanzadas, Instituto Politécnico Nacional, Av. IPN No 2580, Gustavo A. Madero, C.P. 07340, México D.F. El hidrógeno aparece en la actualidad como una de las fuentes de energía renovables, pero se conoce muy poco sobre ella. Entre sus principales ventajas con respecto a otras energías renovables está su posibilidad de generar energía de forma continua, independientemente de las condiciones atmosféricas, con eficiencia superiores al 50 %. Pero aún existen varios aspectos que deben ser mejorados para su implementación a gran escala. En esta plática se expondrán de forma general las distintas etapas y problemáticas que tiene la transición a una “economía del hidrógeno”; desde la obtención y almacenamiento de este compuesto, hasta el diseño de celdas de combustible para su transformación en energía eléctrica. Se comentarán los distintos tipos de celdas de combustible, haciendo énfasis en las llamadas de celdas de estado sólido, y los aspectos científicos (materiales y tecnologías) en los que se está investigando en cada caso. Entre estos aspectos ha crecido el interés en utilizar materiales nanoestructurados, debido a los cambios en las propiedades físico-químicas que producen las restricciones en su tamaño. En esta presentación se exponen además algunos resultados obtenidos en el crecimiento de algunos materiales nanoestructurados en películas delgadas para electrolitos y su posible aplicación en celdas de combustible de temperatura intermedia (~ 600 °C). Los materiales fueron obtenidos por la técnica de rocío pirolítico en su variante ultrasónica y se observó que la disminución del tamaño de grano permite reducir la energía de activación del material y aumenta la conductividad, que es uno de los objetivos fundamentales de las investigaciones en el campo de las celdas de combustible. 473 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SCD-385 ] Polímeros conductores: una alternativa para fabricar dispositivos termoeléctricos Cesia Guarneros Aguilar ([email protected]) 1 1 Catedrática CONACyT, CICATA-IPN Unidad Altamira, Carretera Tampico-Puerto Industrial Altamira Km 14.5, Industrial Altamira, 89600, Altamira Tamaulipas, México Actualmente, el problema de la energía ha atraído mayor atención ya que las fuentes de energía fósiles convencionales algún día se agotarán, por lo que encontrar recursos energéticos alternos es urgente. Mientras tanto, optimizar el consumo energético es un reto, ya que del total de la energía producida sólo se utiliza el 34% y el 66% se pierde como calor disipado. Este calor disipado es producto del trabajo de maquinaria, industrias, refinerías, gas natural, plantas nucleares, estaciones de potencia y automóviles. Sin embargo, parte de esta energía perdida puede convertirse en electricidad. En los últimos años los investigadores han encontrado una nueva manera de aprovechar el calor disipado mediante dispositivos termoeléctricos basados en el “fenómeno Seebeck”, es decir, son capaces de convertir el calor en electricidad. Estos dispositivos se han fabricado de compuestos químicos basados en elementos como el telurio, bismuto, antimonio, silicio, germanio y plomo, pero su fabricación es costosa y no son amigables con el medio ambiente. Debido a esto, la mirada se ha vuelto sobre materiales que pueden hacer este trabajo pero sin dañar al medio ambiente y que su manufactura resulta barata. Algunos polímeros, por ejemplo polianilina, polypirrol y politiofeno, tienen la capacidad de conducir corriente eléctrica y se han considerado para fabricar dispositivos termoeléctricos. Estos materiales conocidos como polímeros conductores tienen una estructura química no saturada lo que permite el flujo de electrones a través de ellos de manera similar al flujo de electrones en los metales. El polímero polianilina es el más investigado debido a que es fácil de sintetizar, tiene excelentes propiedades eléctricas y es muy estable en el ambiente; estas características lo hace un buen candidato para fabricar dispositivos. Hoy día ya se comercializan aparatos que utilizan materiales termoeléctricos en su funcionamiento, por ejemplo los enfriadores portátiles, calentadores y sensores de temperatura, sin embargo, se está trabajando en hacer a estos dispositivos más eficientes y prácticos, pero sobre todo se espera que los polímeros conductores ayuden a alcanzar el objetivo de recuperar energía. 474 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SCD-439 ] Propuestas de la ciencia de materiales para mitigar los efectos del calentamiento global* M. Meléndez-Lira ([email protected]) 1 1 Departamento de Física, CINVESTAV-IPN, Apdo. Postal 14-740, México, DF 07000, México Los efectos del calentamiento global fueron predichos con bases científicas desde el siglo XIX. El primer señalamiento se realizó en 1864 por John Tyndall al descubrir la opacidad del dióxido de carbono a la radiación infrarroja. Actualmente, aun cuando es cada vez más aceptado que las actividades humanas tienen una influencia determinante en el calentamiento global, existen grandes inercias para modificar las actividades que contribuyen a este efecto que pone en riesgo a la humanidad. El sol ha sido la fuente primordial de energía de la tierra siendo el responsable de la aparición y sustento de la vida. La adaptación de la naturaleza para aprovechar la energía solar tiene una de sus máximas expresiones en el proceso de la fotosíntesis. Mediante la fotosíntesis, las plantas acumulan energía vía la transformación del el dióxido de carbono en glucosa. La fotosíntesis y los océanos actuaron durante muchos años como reguladores del dióxido de carbono presente en la atmosfera. Sin embargo el crecimiento explosivo de la humanidad ha generado un exceso de dióxido de carbón y como consecuencia el calentamiento global al ser sobrepasados los reguladores naturales de dióxido de carbono. En esta plática presentaremos en forma breve como la ciencia de materiales puede emplear materiales diseñados para aprovechar el máximo la energía solar en dos formas: 1. Materiales fotovoltaicos que permiten producir energía renovable evitando la quema de hidrocarburos. 2. Materiales que permiten realizar la fotolisis el agua y que acoplados con sistemas |carbono presente en la atmosfera. El éxito en la implementación masiva de estos sistemas constituiría un elemento de ayuda para los procesos naturales de regulación del dióxido de carbono. *: Trabajo financiado parcialmente por CONACyT. 475 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SCD-457 ] Propuesta de Enseñanza Aprendizaje Basado Prototipo Solar Generación de Energía Experimental Luiz Antonio Rasia ([email protected]) 2 , Juliana Maria Meotti 1 1 2 State Technical School July 25, Pedro Américo Street, 479, Ijuí, Brazil Unijuí / DCEEng - Department of Science and Engineering, Sao Francisco Street, 501, Ijuí, Brazil En este trabajo, se propone la construcción de un prototipo de enseñanza para estimular el interés de los estudiantes de secundaria y carreras técnicas en ingeniería por fuentes de energía solar, en particular los sistemas fotovoltaicos. La planificación energética es un punto estratégico para el desarrollo sostenible de un país. Esta propuesta busca que desde la escuela los docentes y las nuevas generaciones estudien y profundicen sobre el tema de energías renovables, principalmente la solar, y sean parte activa en la solución de la problemática energética y ambiental que enfrenta nuestro planeta. Esto ha motivado la investigación de fuentes limpias de energía como los sistemas solares y plantas de energía eólica, ya que son de bajo impacto ambiental renovable. La opción para la generación de energía solar fotovoltaica es debido a la simplicidad de la obtención de este tipo de energía generada por conversión directa de luz en electricidad mediante el efecto fotovoltaico. En esta propuesta se enseñan los conceptos básicos de energía, energías renovables y sus aplicaciones, destacando la importancia de la energía solar para la vida en la Tierra. En las últimas décadas la ciencia y la tecnología se ha convertido en los grandes símbolos de los avances en el mundo y en los últimos años, muchas de las áreas de pregrado prácticamente desaparecido de las ofrendas regulares de las instituciones educativas del interior de Brasil y dio lugar a las áreas de la ingeniería. En este contexto, los jóvenes que también tenían algún interés en el seguimiento de las áreas de la enseñanza comenzaron a migrar a las áreas de técnica, creando una nueva demanda de afiliación. 476 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SCD-471 ] El futuro deformable, flexible y elástico para la electrónica Roberto Ambrosio Lazaro ([email protected]) 1 1 Facultad de ciencias de la Electrónica, BUAP, Edif. 109B. Ciudad Universitaria. 18 Sur y Avenida San Claudio. San Manuel. Puebla, Pue. La electrónica flexible es la puerta de entrada a una nueva generación de dispositivos electrónicos tales como: pantallas, teléfonos , implantes cerebrales , miembros artificiales , celdas solares y otros dispositivos sin límites que se benefician de la capacidad de doblar , enrollar y cambiar de forma. Los grupos de investigación en el mundo han desarrollado pantallas súper-ligeras y flexibles que podrían se usadas como pantallas de papel pintado en la pared o que podrían funcionar como iluminación, electrónica vestible, entre otras aplicaciones. Sin embargo el problema es encontrar la manera de hacerlo. El investigador John Rogers de la universidad de Illinois en Urban–Champaign ha descrito que la electrónica del futuro deberá ser elástica y suave. Debido a que los dispositivos basados en esta nueva tecnología deben de tener la capacidad de estirarse, girar , ser deformables en formas curvilíneas, permitiendo así aplicaciones que serían imposibles de lograr mediante el uso de la electrónica de hoy en día basada en circuitos y dispositivos mecánicamente rígidos. Los grupos de investigación en el campo de la microelectrónica creen que el próximo hito es desarrollar sistemas electrónicos que eviten la naturaleza rígida, frágil, y plana que se tiene actualmente, para permitir nuevos modos de uso. Se ha desarrollado investigación en este campo desde hace mas de 15 años, primeramente por el desarrollo de pantallas de gran área y flexibles. Pero el alcance se ha expandido hacia posibilidades en dispositivos biomédicos que se integren íntimamente con el cuerpo humano y en los diseños de productos que explotan las formas curvilínea, ergonómica, o diseños de inspiración biológica. ¿Te has imaginado un tatuaje electrónico en la piel? ¿Para que crees que sirva? En este trabajo se presenta un enfoque hacia el desarrollo de la tecnología para la electrónica deformable y flexible, hasta llegar a aplicaciones de electrónica vestible. Se describen el desarrollo de nuevos materiales electrónicos, como, semiconductores orgánicos que se pueden flexionar, los conductores de materiales compuestos que se pueden estirar. Métodos alternativos de obtención de los materiales inorgánicos semiconductores, hasta su aplicación en dispositivos. Se discuten las aplicaciones mas recientes en áreas de la biomedicina como el monitoreo intra- cardíaco y neuronal. Así como diodos emisores de luz orgánicos y sensores para robótica entre otros. 477 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SCD-528 ] De Micro a Nano y lo que sigue, Mas allá de la Ley de Moore Alfonso Torres ([email protected]) 1 1 LI-MEMS, INAOE, Puebla, Mexico, [email protected] Desde principio de los años 70´s, la fortaleza de la industria de semiconductores ha sido su habilidad de seguir la Ley de Moore, siendo esta el motor de un círculo virtuoso: a través del escalamiento, se obtiene una mejor relación funcionamiento/costo, que resulta en un crecimiento exponencial del mercado de semiconductores. La industria electrónica encara ahora una nueva tendencia, “More than Moore” (MtM), mediante la que nuevo valor se agrega a dispositivos a través de la incorporación de funcionalidades que no necesariamente escalan de acuerdo a la Ley de Moore. Se tratará de explicar que es MtM y que oportunidades ofrece esta nueva perspectiva de desarrollo de la industria electrónica y lo que en el LIMEMS-INAOE realizamos dentro de esta área de investigación. [ SCD-529 ] Electronica y microsistemas; ciencia y tecnologia de lo pequeño en méxico Wilfrido Calleja ([email protected]) 1 1 LI-MEMS INAOE, Puebla, Mexico, [email protected] La ciencia y la tecnología en general, con su uso generan un impacto positivo en favor de la Economía y de la Sociedad de quienes las desarrollan. En su vertiente relacionada con la Electrónica moderna, representa una oportunidad de desarrollo para nuestro país. La Microelectrónica es una tecnología que se ha desarrollado para la fabricación de circuitos integrados (chips) utilizando como materia prima un tipo especial de materiales conocidos como semiconductores. En la industria Electrónica transnacional, los chips se utilizan como componente principal en la fabricación de sistemas electrónicos tales como teléfonos celulares, TV Inteligente, equipos de audio y una amplia variedad de sistemas computarizados de gran utilidad en áreas tales como ingeniería Biomédica, telecomunicaciones, industria automotriz, etc. La Microelectrónica es una rama de la Ingeniería Eléctrica, cuyo producto principal es el microprocesador, un chip bastante complejo en su funcionamiento, en el cual su elemento 478 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla básico es el transistor. En esta tecnología el prefijo “Micro” se refiere a que las dimensiones físicas del transistor, son del orden del micrómetro ó micra. Los términos microelectrónica y microchip siguen vigentes aún cuando en la actualidad los transistores tienden hacia el tamaño nanométrico. La Microelectrónica ha basado su desarrollo principalmente en los avances de la Ciencia de Materiales, para producir nuevos materiales semiconductores y dieléctricos que posibilitan la fabricación de sensores de amplio espectro y modernos actuadores. La tecnología de microelectrónica establece los fundamentos para el desarrollo de nuevas tecnologías que integran circuitos convencionales con sensores y actuadores, tal como los Sistemas MicroElectroMecánicos (MEMS, Microsistemas). En el contexto de Economía, se ha identificado que los Recursos Humanos especializados en la Ciencia de Materiales y Microelectrónica, son un bloque fundamental para el avance de la Tecnología y que la industria Electrónica los demanda como un factor clave para construir sus plantas de investigación, desarrollo tecnológico y producción industrial. En tanto este requisito está vigente en todas las áreas de la Ciencia y Tecnología; es particularmente relevante para la Nanotecnología, Nanoelectrónica y Microsistemas; que siendo tecnologías de vanguardia, además influyen en todas las áreas de la Investigación Científica. Estudios de prospección realizados en los Estados Unidos de Norteamérica, comunidad europea y en los principales países de Asia, arrojan como resultado la necesidad de técnicos especializados en Nanotecnología y Microelectrónica, del orden de cientos de miles de especialistas. Por lo anterior, si se atiende esta tendencia tecnológica mundial, el establecimiento de un sistema educativo especializado en México será esencial para que sea posible desarrollar Nanotecnología, Microelectrónica y Nanoelectrónica Nacional, tecnologías que darán lugar al desarrollo innovador de nuevos materiales, procesos de manufactura y sistemas electrónicos modernos. En esta conferencia se aborda la importancia de la Microelectrónica en México como tecnología nodriza para el desarrollo de los Microsistemas, Nanoelectrónica y Nanotecnología, y su potencial influencia en el sistema educativo y la Economía de nuestro país. 479 Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. VIII International Conference on Surfaces, Materials and Vacuum September 21st – 25th, 2015 Puebla, Puebla [ SCD-536 ] ¿Los objetos tienen color? Juana Medina Márquez ([email protected]) 1 1 INAOE, Laboratorio de Visión por Computadora (LVC), Puebla, Mexico, [email protected] Si pregunto al azar, en la calle o en el trabajo, a una persona ¿de qué color son las hojas de los árboles?, ¿de qué color es la sangre?, ¿de qué color son las manzanas?, ¿de qué color es la rosa que está en tu jardín?, ¿de qué color es tu carro?..., puedo asegurar casi al cien por ciento que sus respuestas serán verde, roja, amarilla, azul. Estamos tan acostumbrados a hablar de colores, que damos por hecho tales afirmaciones, sin detenernos a pensar si nuestras respuestas son acertadas. Les propongo que antes de responder, nos formulemos esta pregunta: ¿los objetos tienen color? Si no están seguros de lo que responderán, los invito a que juntos nos adentremos a este mundo maravilloso de la interacción entre la luz y la materia, y vayamos poco a poco descubriendo y contes