Exciton and impurity electroabsorption in GaSexTe1-x〈Sn〉 single crystals

The exciton and impurity electroabsorption has been studied in GaSe_xTe_1-x〈Sn〉 (0.7 ?χ?1) exhibiting the properties of residual conductivity (RC). It has been shown that the broadening of the negative exciton peak, the nature of the field dependence of the electroabsorption signal, and its anisotropy in the exciton and impurity region are associated with the presence of internal chaotic fields E_int ≈ 10³ ? 10⁴ V cm^?1 coming into play because of the fluctuating distribution of the tin impurity and the defects inherent in layer crystals. Based on investigations of the impurity electroabsorption (IEA), the depth of occurence (hv = 1.18 eV) and the concentration (N = 10¹⁶cm³) of impurity centres have been determined.