First principles study of the structural, electronic and optical properties of ZnS xSe 1− x alloys

Abstract

The structural, electronic and optical properties of ZnS x Se 1− x alloys have been investigated using density functional theory by Wien2k package. The exchange correlation potential is treated by the local density approximation (LDA), generalized gradient approximation (GGA), Engel–Vosko generalized gradient approximation (GGA_EV) and GGA_EV plus U (GGA_EV+U). The calculated real and imaginary parts of the dielectric function and the reflectivity of ZnS x Se 1− x alloys are in good agreement with the available experimental results particularly in GGA_EV and GGA_EV+U. I have studied the effect of composition on the equilibrium volume, bulk modulus, energy band gap and the static dielectric constant and static reflectivity spectra. Furthermore the effect of hydrostatic pressure on the electronic and optical properties of these alloys has been investigated. The first and second order pressure coefficient for the energy band gaps, the static dielectric function and the static reflectivity spectra have been calculated.