Density functional study of CdS1–xSex and CdS1–xTex alloys

Abstract

The present work performs self-consistent ab initio full potential-linearized augmented plane wave method to study the structural, electronic, optical and thermodynamic properties of CdS1–xSex and CdS1–xTex semiconductor alloys using generalized gradient approximation (GGA) by Perdew–Burke–Ernzerhof (PBE) and Engel–Vosko (EV). The ground-state properties were determined for the bulk materials CdS, CdSe, CdTe and their alloys. A small deviation of the lattice parameter from Vegard’s law was observed for CdS1–xSex and CdS1–xTex alloys. A large deviation of the bulk modulus from linear concentration dependence (LCD) was observed for two alloys. We have also investigated the effect of composition on bonding properties and correlated it to the charge-exchange effect in the optical bowing. Using the approach of Zunger et al. the microscopic origins of the gap bowing were also explained. The refractive index and optical dielectric constant for the alloys of interest are calculated. The thermodynamic stability of the alloys was investigated by calculating the critical temperatures.