1. The concentrations of impurities and point defects in melt grown ZnSe
Sergiy Galkin
Institute for Scintillation Materials of NAS of Ukraine,
60 Lenin ave., Kharkov 61158, Ukraine

2. Luminescent parameters of the ZnSe at low temperatures depend on:
presence of chemical impurities (especially polyvalent metals).
violations of the stoichiometric composition (due to the formation polyselenids).
presence of point defects that can act as traps and scattering centers.

3. Contents of the main impurities in the charge and the grown ZnSe crystal
Admixture
Charge
(mas. %)
Krystal Ag
< 210-5 Cd
< 310-5 Cu
< 710-6
910-5 Mg
< 110-6
2.710-4 Al
< 210-6
2.110-3 Cr
< 410-6
710-6 Ca
< 310-6
410-3 Mn
4.710-5 Fe
8.510-4 Ni
< 610-6 Sn Sb Pb
< 510-5 Si
1.310-3 S
< 110-4 С
110-3
4.810-2 О
110-4
4.610-2

4. Optical absorption in the infrared spectrum
Distribution of the absorption coefficient along the axis of the ZnSe crystal
ZnSe transmission spectra before (1) and after (2) heat treatment in zinc vapor

5. The concentration of VZn, V’Zn and V∙Se in ZnSe is
reduced by the low-temperature heat treatment
Zn-Se phase diagram

6. Defects formation process by ZnSe crystals growing
ZnSel → Zng + 1/2Se2 Zn
Increase concentration vacancies factors
Effects in ZnSe
Melt overheating
Stoichiometry disbalance
Isovalent substitution
Local deformation of crystal lattice
Donor doping
Vacancies generation in conformity with electric neutrality rule Se
VZn

7. Cation doped ZnSe lattice paramethers
Entering into the crystal a small amount of a donor impurity ZnSe lattice parameter decreases due to the generation of vacancies

8. Point defects and ZnSe scintillation parameters
Defects complex
ZnSe stoichiometry
Luminescence, nm
VSe ­- OSe- VZn
Se excess
970
VZn - Zni – MZn
Stoichiometric composition
640
VZn - Zni
Zn excess
610
Exciton
460

9. Conclusions The ZnSe luminescence intensity depends on the:
- carbon impurities amount;
composition and concentration of point defects.
Very important is optimal regime of ZnSe thermal treatment.