Calculation of structural, optical and electronic properties of ZnS, ZnSe, MgS, MgSe and their quaternary alloy Mg1−xZnxSySe1−y

The structural and electronic properties of the binary semiconductor compounds ZnS, ZnSe, MgS and MgSe in the cubic structure are calculated using the self-consistent scalar-relativistic full potential linear-augmented plane wave method (FP-LAPW) within the local (spin) density approximation (LSDA). From the calculated values of the band-gap energy we have determined the electronic and optical properties of quaternary alloys Mg1−xZnxSySe1−y using the simple tight-binding sp3s* theory, which incorporates compositional disorder as an effective potential. In addition, the refractive index of MgS, MgSe, ZnS and ZnSe was computed using both real and imaginary parts of the dielectric function. The result indicates that the refractive index increases with allowing for the Mg1−xZnxSySe1−y lattice matched to GaAs.