Photoluminescence study of γ-irradiation effect on the defect structure in Ge-doped CdTe single crystals

An effect of γ-irradiation in the dose range 10-500 kGy on the defect structure of Ge-doped CdTe single crystals (CdTe:Ge) was investigated via the method of low-temperature photoluminescence. It was obtained that γ-irradiation in mentioned above dose range leads to the substantial decreasing of intensities of excitonic emission bands - D0X, A0X, VDX and increase in the intensities of impurity-related emission bands - eA1,eA2, DA. It was shown that such changes in the luminescence can be explained by radiation-stimulated redistribution of luminescence centers between recombination channels. The latter includes vacancy-type defects filling by Ge dopant atoms which leads to the improving of the crystalline perfection of irradiated CdTe:Ge crystals. Mentioned material quality increasing was confirmed analysing the electron-LO-phonon coupling in irradiated crystals which was characterized via the Huang-Rhys factor for corresponding luminescence bands. For the verification of the assumption about radiation-stimulated compensation of native defects the resonant Raman measurements also were carried out. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)