Ab-initio study on the phase transition, elastic, optoelectronic, and thermodynamic properties of GaAs1-xSbx

Abstract

In this study, structural properties of the zinc-blende (B3) phase and its transition pressure and other important physical properties of GaAs, GaSb compounds, and their mutual alloys for x = 0.25, 0.5 and 0.75 concentration of the Sb are investigated. The computations are carried out using a full-potential (FP) linearised (L) augmented plane wave plus local orbital method (APW + lo) designed within the density functional theory (DFT). The calculations of the structural properties are done at the level of Wu-Cohen generalized gradient approximation (WC-GGA), Perdew-Burke-Ernzerhof approximation (PBE-GGA), as well as Perdew-Wang local density approximation (PW-LDA). Whereas the elastic constants are calculated using WC-GGA. However, to obtain consistent results of the electronic properties, the calculations are carried out by employing Engle-Vosko (GGA) and Tran-Blaha (TB) modified Becke-Johnson (mBJ) potential approach. For each concentration, the pressure-induced phase transition of zinc blende (B3) to rocksalt (B1) structure is investigated. Our band structure calculations show that the alloys are of direct band nature with bandgap energies in a range from 1.559 eV to 0.861 eV with increasing Sb. Furthermore, optical parameters at the level of the mBJ approach are also determined over a range from 0.0 eV to 40.0 eV. From the analysis of our obtained results of enthalpy of mixing, ΔHm, and other properties, it is found that the alloys under investigation are stable over a wide range, and suitable candidates for photovoltaic applications over a wide range of the solar spectrum including visible region.