Ab-initio study of ordered III–V antimony-based semiconductor alloys $$\mathbf{GaP }_{1-x}{} \mathbf{Sb} _{x} \mathbf{and} AlP _{1-x}{} \mathbf{Sb} _{x}$$

Abstract

In this work, we have investigated the structural, electronic and thermodynamic properties of GaP $$_{1-x}$$ Sb $$_{x}$$ and AlP $$_{1-x}$$ Sb $$_{x}$$ ternary alloys for a number of ordered structures and compositions in a series of first-principles calculations within the density functional theory, using full potential-linearised augmented plane-wave (FP-LAPW) method, as implemented in the WIEN2k code. The exchange-correlation effect was treated within the generalised gradient approximation (GGA) in the form of GGA-PBEsol to optimise the structure and to compute the ground-state properties. In addition to the GGA, the modified Becke–Johnson (mBJ) potential coupled with the spin-orbit interaction (SOI) was also applied to obtain reliable results for the electronic properties. Our investigation on the effect of composition on lattice constant, bulk modulus and band gap showed almost nonlinear dependence on the composition. The GaP $$_{1-x}$$ Sb $$_{x}$$ and AlP $$_{1-x}$$ Sb $$_{x}$$ alloys are found to be semiconductors with a positive energy gap for the whole concentration range. The spin-orbit splitting $$\Delta _{\mathrm {SO}}$$ was found to increase with Sb composition with a marginal bowing parameter. Besides, a regular-solution model was used to investigate the thermodynamic stability of the alloys which mainly indicates a phase miscibility gap. In addition, the quasiharmonic Debye model was applied to analyse the effect of temperature and pressure on the Debye temperature and heat capacity.