Effect of γ-irradiation on the optical and electrical properties of PbxGe42−xSe48Te10

The composition dependence of optical and electrical of amorphous unirradiated and γ-irradiated thin films of PbxGe42-xSe48Te10 (5 ≤ x  ≤ 16) deposited by thermal evaporation was measured as a function of wavelength (0.3 μm ≤ λ ≤ 2.5 μm). The optical transition was found to be indirect. The optical energy gap (Eopt) decreases with increasing concentration of Pb at.wt.% and exhibits a minimum value for the composition with 9  at.wt.% Pb and the results have been interpreted in terms of the average bond energy. The band tail (Ec) obeys Ubarch's empirical relation. The d.c. electrical resistance was measured in a temperature range of (300-455 K). The activation energy for electrical conduction decreased with increasing Pb concentration. The electronic conduction in the temperature range has been attributed to band transport mechanism. The effect of γ-radiation on the optical constants (n, k), band tail (Ec) and Eelect energies as a function of composition has been determined. The results show that, the radiation causes increase in optical and electrical energies as γ-doses increase.