Influence of the photo- and X-ray excitation intensity on the conductivity and luminescence of ZnSe

1. OMEE-2007 A.O. Sofiienko, V.Ya. Degoda 1
Influence of the photo- and X-ray
excitation intensity on the
conductivity and luminescence of ZnSe
Kyiv National Taras Shevchenko University, Physics Department
Glushkova ave., 2, k.1, Kyiv 03022
A.O. Sofiienko, V.Ya. Degoda

2. OMEE-2007 A.O. Sofiienko, V.Ya. Degoda 2
• Experimental investigation of the photo- and X-ray
conductivity and luminescence of ZnSe at different
levels of the X-ray excitation.
The purpose of the work
• The estimation of the fundamental differences
between the physical processes in the
semiconductors at the detection of the photo- and
X-ray photons.

3. OMEE-2007 A.O. Sofiienko, V.Ya. Degoda 3
• Charge transport in ZnSe semiconductor and its
evaluation as a detector of the ionizing radiation.
Actuality of the work
• The complex research of the conductivity and
luminescence enables to perform more deep
analysis of the kinetics of charge transport, which
is important for its theoretical argumentation.

4. OMEE-2007 A.O. Sofiienko, V.Ya. Degoda 4
A schematic of the experimental set-up
h
 
Sample
Cryostat
γ
PMT
MDR - 2 PMT
X-ray tube
AD - 2 AD - 3
PC
U(V)
AD - 1
i(рA)
UV source (385 nm)


5. OMEE-2007 A.O. Sofiienko, V.Ya. Degoda 5
Fig.1. Measured X-ray luminescence (XRL) and photoluminescence (PL) spectra
of monocrystalline ZnSe at the temperature of 90K.
400 500 600 700 800 900 1000 1100
0
400
800
1200
1600
2000
2400
I()
, nm
x10
x25
630 nm
640 nm
970 nm
XRL PL

6. OMEE-2007 A.O. Sofiienko, V.Ya. Degoda 6
Fig. 2. Measured XRL and PL spectra of polycrystalline ZnSe at the
temperature of 90K.
400 500 600 700 800 900 1000 1100
0
1000
2000
3000
4000
5000
PLXRL
I()
x20
, nm
970 nm
630 nm
800 nm
546 nm
453 nm

7. OMEE-2007 A.O. Sofiienko, V.Ya. Degoda 7
4 6 8 10 12 14 16 18 20
100
200
300
400
500
600
IT, mA
XRL(IT)
546 nm970 nm
250
500
750
1000
1250
1500
1750
XRL(IT)
Fig. 3. The dependence of the intensity of X-ray luminescence in spectrum of
polycrystalline ZnSe on the current of X-ray tube at the temperature of 90 K.

8. OMEE-2007 A.O. Sofiienko, V.Ya. Degoda 8
100 200 300 400 500 600
300
400
500
600
700
800
900
1000
1100
1200
1300
Id, abs. unit.
PL(Id)
970 nm 630 nm
100
150
200
250
300
350
400
450
500
550
600
PL(Id)
Fig. 4. The dependence of the intensity of photoluminescence in spectrum of
polycrystalline ZnSe on the intensity of UV source at the temperature of 90 K.

9. OMEE-2007 A.O. Sofiienko, V.Ya. Degoda 9
200 400 600 800 1000 1200
0
100
200
300
400
500
PL(Id) XRL(IT)
Id, abs. units.
640 nm
0 5 10 15 20 25 30
0
500
1000
1500
2000
2500
IT, mA
630 nm
Fig. 5. The Dependencies of the intensities of photoluminescence in spectrum of
monocrystalline ZnSe on the intensity of UV source (red) and on the current of X-ray
tube (blue) at the temperature of 90 K.

10. OMEE-2007 A.O. Sofiienko, V.Ya. Degoda 10
0 50 100 150 200
0
20
40
60
80
100
90 K300 K
U, V
0
50
100
150
200
250
300
j(U), nA j(U), nA
Fig. 6. Volt-ampere characteristics of the X-ray induced conductivity (XRC) of the
monocrystalline ZnSe at different ambient temperatures.

11. OMEE-2007 A.O. Sofiienko, V.Ya. Degoda 11
Fig. 7. Volt-ampere characteristics of the photo induced conductivity (PC) of
monocrystalline ZnSe at different ambient temperatures.
0 50 100 150 200
0
500
1000
1500
2000
90 K300 K
U, V
j(U), pA
0
20
40
60
80
j(U), nA

12. OMEE-2007 A.O. Sofiienko, V.Ya. Degoda 12
200 400 600 800 1000 1200
0
50
100
150
200
250
300
350
400
Id, arb. un.
j(U), nA
150 V
100 V
50 V
Fig. 8. Lux-ampere characteristics of the monocrystalline ZnSe
at the temperature of 90 K (photoexcitation).

13. OMEE-2007 A.O. Sofiienko, V.Ya. Degoda 13
200 400 600 800 1000 1200
0
10
20
30
40
50
60
j(U), nA
Id, arb. un.
150 V
100 V
50 V
Fig. 9. Lux-ampere characteristics of the monocrystalline ZnSe
at the temperature of 300 К (photoexcitation).

14. OMEE-2007 A.O. Sofiienko, V.Ya. Degoda 14
Fig. 10 Lux-ampere characteristics of the monocrystalline ZnSe
at the temperature of 300 К (X-ray excitation).
4 6 8 10 12 14 16 18 20 22
200
400
600
800
1000
1200
1400
j(U), pA
IT, mA
150 V
100 V
50 V

15. OMEE-2007 A.O. Sofiienko, V.Ya. Degoda 15
200 400 600 800 1000 1200
0
100
200
300
400
500
600
j(U), nA
Id, arb. un.
150 V
100 V
50 V
Fig. 11. Lux-ampere characteristics of the polycrystalline ZnSe
at the temperature of 90 K (photoexcitation).

16. OMEE-2007 A.O. Sofiienko, V.Ya. Degoda 16
Conclusions
1.The comparison of the spectra of photo- and X-ray-
induced luminescence of ZnSe poly- and
monocrystals shows that their intensities have linear
dependence on the excitation intensities of the used
X-ray source and UV photodiodes, and only at small
excitation levels some non-linearity is observed.

17. OMEE-2007 A.O. Sofiienko, V.Ya. Degoda 17
Conclusions
2. The functional dependencies of the luminescence
intensity of ZnSe on the excitation level are identical
at Photo- and X-ray excitations. It indicates the
similarity of the kinetics processes of charge carrier
recombination in both cases.

18. OMEE-2007 A.O. Sofiienko, V.Ya. Degoda 18
Conclusions
3.The investigation of the lux-ampere characteristics of
ZnSe shows that there is a dependence between the
temperature of ZnSe samples and the linearity in
functional dependence between conductivity current
and excitation level. We observed smaller
nonlinearity for ZnSe polycrystals at the temperature
of 90 K.