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Low temperature luminescence spectra of ZnSe1-xTex mixed crystals with Te concentration up to 22 at % have been studied for the first time. Strong exciton localization by the aggregates composed by several Te atoms has been observed. The increase of Te concentration leads to the onset of energy migration through the localized states which can be considered as an analogue of the Anderson transition in the system of localized excitons.

The reflection and luminescence spectra of ZnxCd1−xSe solid solutions (0.8 < x < 1.0) have been studied. The features of these spectra due to the influence of the composition large-scale fluctuations on the exciton states have been found, i.e. (1) disorder induced broadening of exciton reflection lines (2) observation of the IL photoluminescence line caused by localized exciton states.

The temperature and concentration dependences of exciton emission spectra in ZnxCd1−xSe solid solutions (0 < x < 1) have been studied. It has been shown: (1) high efficiency of the luminescence of localized exciton states (LES) produced by large-scale potential fluctuations, (2) absence of the energy gap between LES and exciton band bottom states. Results obtained have common meaning for ideal solid solutions, in which distribution of substitutional atoms is random.