osl radiation dosimetry using boron doped cvd diamond films

osl radiation dosimetry using boron doped cvd diamond films

OSL RADIATION DOSIMETRY USING BORON DOPED CVD DIAMOND FILMS
J. A. N. Gonçalves1, G. M. Sandonato1, R. Meléndrez2, V. Chernov2, R. Bernal2, M. Pedroza2, C. Cruz-Vázquez3, F. Brown3, M.
Barboza-Flores2
1
Laboratório Associado de Plasma, Instituto Nacional de Pesquisas Espaciais C.P. 515-12201-970, São Jose dos Campos, SP,
Brazil
2
3
Centro de Investigación en Física de la Universidad de Sonora, Apdo. Postal 5-088, Hermosillo, Sonora, 83190 México
Departamento de Investigación en Polímeros y Materiales de la Universidad de Sonora, Apdo. Postal 130, Hermosillo, Sonora,
83000 México
The optically stimulated luminescence (OSL) properties of chemically vapor deposited (CVD) boron doped diamond films exposed to
β radiation were investigated. Diamond thin films deposited on silicon (111) containing a B/C ratio of 2 000, 4 000, 8 000, 12 000
and 20 000 ppm were exposed to a β -ray dose of 0.8 – 3000 Gy. After stimulation with 470 nm light the OSL decay curve was
measured and found it to be proportional to the dose exposure. The thermoluminescence (TL) glow curve indicate the existence of
main charge carriers traps around 150 and 250 oC for a diamond film with B/C ratio of 12 000. The OSL emission appears to originate from
charge trapped at the 150 oC glow peak. The results indicate that CVD diamond films performs well as OSL dosemeter for ionizing radiation;
however additional investigation is needed in order to fully understand the nature of the trapping and recombination mechanism responsible for
the OSL dosimetric properties. This work was supported by Fundação de Amparo a Pesquisa do Estado de São Paulo (FAPESP). We
acknowledge financial support from SEP and Conacyt grants No.36521, 37641 and 32069.
Thermoluminescence of diamond
thin films
100
Concentración Boro/Carbono
Termoluminiscencia (u.a.)
Dosis (Gy)
80
de 4000 ppm
3000
1500
900
300
100
25
5
2.5
0.8
60
40
20
0
0
100
200
300
400
500
Temperatura (o C)
• Figura 1.- TL glow curves of beta irradiated diamond films
ppm.
de B/C de 4000
Thermoluminescence of diamond
films
100
Concentración Boro/Carbono
Termoluminiscencia (u.a.)
Dosis (Gy)
80
de 12000 ppm
3000
1500
900
300
100
25
5
2.5
0.8
60
40
X100
20
X20
0
0
100
200
300
400
500
Tem peratura ( o C)
• Figura 2.- TL glow curves of diamond films B/C = 12000
ppm, exposed to beta rays at diferent doses.
Thermoluminescence of daimond
films
Termoluminiscencia (u.a.)
100
Película de diamante (300 Gy)
Sustrato de Si poroso (600 Gy)
Sustrato de Si cristalino (600 Gy)
80
60
40
20
0
0
100
200
300
400
500
Temperatura (o C)
• Figura 3.- TL glow curves of a diamond film with B/C = 12000 ppm as compared to
the TL obtained from a crystaline and porous Si substrate.
OSL of diamond films
100
Concentración Boro/Carbono de 4000 ppm
80
3000
1500
100
300
2.5
5
25
OSL (u.a.)
Dosis (Gy)
900
0.8
60
40
20
0
0
8
16
24
32
40
Tiempo (Segundos)
• Figura 4.- OSL of diamond film containing B/C = 4000 ppm exposes
toa beta irradiation and photostimulated with blue light.
OSL of diamond films
100
Concentración Boro/Carbono de 12000 ppm
80
3000
1500
100
300
2.5
5
25
OSL (u.a.)
Dosis (Gy)
900
0.8
60
40
20
0
0
8
16
24
32
40
Tiempo (Segundos)
• Figura 5.- OSL of diamond film containing B/C = 12000 ppm
exposed to beta rays and photostimulated with blue light.
TL and OSL dosimetry
Dosimetría (Concentración Boro/Carbono)
Intesidad de TL (u.a.)
80
TL (12000 ppm)
OSL (12000 ppm)
TL (4000 ppm)
OSL (4000 ppm)
60
40
X10
20
0
0
600
1200
1800
2400
3000
Temperatura (o C)
• Figura 6.- Dosimetric behavior of diamond thin films containing
different B/C concentration.
TL fading
100
Concentración Boro/Carbono
Termoluminiscencia (u.a.)
de 4000 ppm
TL IRRADIADA CON 300 Gy
80
TL DESPUÉS DE 12 HRS.
60
40
20
0
0
100
200
300
400
500
Temperatura (oC)
• Figura 7.- TL fading of a diamond film containing B/C = 4000 ppm
exposed to 300 Gy of beta irradiation.
TL fading
Termoluminiscencia (u.a.)
100
TL IRRADIADA CON 300 Gy
TL DESPUÉS DE 12 HRS.
80
Concentración Boro/Carbono
de 12000 ppm
60
40
20
0
0
100
200
300
400
500
Temperatura (oC)
• Figura 8.- TL fading of a diamond film B/C = 12000 ppm, exposed
to 300 Gy of beta irradiation.
TL fading
Intensidad de TL (u.a.)
100
Concentración B/C de 12000 ppm
Concentración B/C de 4000 ppm
80
60
40
20
0
0
10000
20000
30000
Tiempo (Segundos)
40000
50000
• Figura 9.- TL fading of diamond samples containing B/C = 4000 and
12000 ppm, after 300 Gy of beta rays.
Residual TL after OSL
100
Concentración Boro/Carbono
Termoluminiscencia (u.a.)
Dosis (Gy)
80
de 4000 ppm
3000
1500
900
300
100
25
5
2.5
0.8
60
40
20
0
0
100
200
300
400
500
Temperatura (oC)
• Figura 10.- Residual TL after OSL for diferent irradiation beta doses.
Residual TL after OSL
Termoluminiscencia (u.a.)
100
Concentración Boro/Carbono
Dosis (Gy)
de 12000 ppm
3000
1500
900
300
100
25
5
2.5
0.8
80
60
40
X100
20
X20
0
0
100
200
300
400
500
Temperatura (o C)
• Figura 11.- Residual TL (diamond film with B/C = 12000 ppm) after OSL at
diferente bet irradiation dose.
Conclusions
• The TL as well as the OSL signal increases as the
•
•
•
•
concentration of B/C increases.
The existence of TL after OSL indicates diferent
recombination mechanisms for the TL and OSL
processes.
TL signal appears in both sides of the substrate. It is
necessary to identify what causes TL and OSL.
TL stability is found in samples with lower B/C
concentrations.
The OSL decays more faster in samples of lower B/C
concentration.