Depth inhomogeneity of ZnTe, CdZnTe, ZnSe epilayers grown on (001)GaAs of MBE

In this work we report the depth inhomogeneity study of MBE grown ZnSe, CdZnTe and ZnTe/(001) GaAs epilayers of different thickness by x-ray and depth resolved photoluminescence methods. Step etching and different wavelength excitation were used for this purpose. It is shown that all these epilayers consist of three regions with different extended defect and impurity concentrations: (i) near the interface one with high density of misfit dislocations and impurities concentration; (ii) the region with low extended defect and impurity concentration and (iii) near the top surface region with higher extended and point defect concentration. The deterioration of near top surface region increases with epilayer thickness. Influence of GaAs substrate preparation regimes on ZnSe layer growth and optical properties as well as the study of interdiffusion of Ga and Zn across the wafer-epilayer interface have been investigated. The possibility to use thin intermediate ZnTe layer with solid phase crystallization for blocking of the interdiffusion in ZnTe layers and improvement of epilayer photoluminescence characteristics have been explored.