Optoelectronic properties of zinc blende ZnSSe and ZnBeTe alloys

The compositional dependence of the electronic band structure has been computed for zinc blende ZnSxSe1-x and Zn1-xBexTe alloys with composition x ranging from 0 to 1. The empirical pseudo potential method with the virtual crystal approximation have been used. A particlar attention has been paid to the effect of alloy disorder on the electronic properties of the II-VI studied compounds. For this purpose, the compositional disorder is added to the virtual crystal approximation as an effective potential. Such correction approximates significantly our calculated values of the band gap bowing parameters to experimental ones. The ZnSxSe1-x gap energy shows a nonlinear behavior with strong bowing for low compositions of sulfur. The Zn1-xBexTe compound, as it is known, can be direct or indirect semiconductor depending on its beryllium composition x. The electron effective mass and the refractive index have been investigated as well. Polynomial approximations are obtained for both the energy gap and the effective mass as functions of alloy composition at and X valleys.