Structural and Physical Properties of ZnS_xSe_1-X Thin Films

Abstract

ZnS_xSe_1-x thin films with various x values in the range from 0 to 1 were prepared by vacuum evaporated technique on glass substrates using powders of ZnS and ZnSe. The structure, surface morphology and composition of thin films have been investigated by XRD, SEM and EDAX techniques. The composition analysis and the diffraction patterns revealed that ZnS_xSe_1-x thin films are nearly stoichiometric and have a cubic zinc blende type structure, with a strong orientation of the crystallite along the crystalline plane (111). The temperature dependence of electrical conductivity measured in a temperature range of 300–500 K demonstrated that the films are of n-type conductivity. The thermal activation energy was evaluated from electrical measurements, and the transparency of films in the wavelength range of 380–1100 nm has been demonstrated from oprical measurements. The lifetime of nonequilibrium charge carriers was determined from the relaxation curves of photoconductivity and photoluminescence, and the energy levels of recombination and trapping centers have been determined from the spectral dependence of photoluminescence and thermoluminesce.