First-principle calculations of the structural, electronic, thermodynamic and thermal properties of ZnS x Se1−x ternary alloys

First-principle calculations were performed to study the structural, electronic, thermodynamic and thermal properties of ZnSx Se1−x ternary alloys using the full potential-linearized augmented plane wave method (FP-LAPW) within the density functional theory (DFT). In this approach the Wu-Cohen generalized gradient approximation (WC-GGA) and Perdew-Wang local density approximation (LDA) were used for the exchange- correlation potential. For band structure calculations, in addition to WC-GGA approximation, both Engel-Vosko (EV-GGA) generalized gradient approximation and recently proposed modified Becke-Johnson (mBJ) potential approximation have been used. Our investigation on the effect of composition on lattice constant, bulk modulus and band gap for ternary alloys shows a linear dependence on alloy composition with a small deviation. The microscopic origins of the gap bowing were explained using the approach of Zunger and co-workers. Besides, a regular-solution model was used to investigate the thermodynamic stability of the alloys which mainly indicates a phase miscibility gap. Finally, the quasi-harmonic Debye model was applied to see how the thermal properties vary with temperature at different pressures.