An ab initio study of the "direct-indirect band gap" transition in AlxIn1-xP alloys

The composition-induced "direct-indirect" band gap transition in the AlxIn1-xP alloys was studied theoretically. Two different approaches - virtual crystal approximation and supercell-based calculations, both in the general gradient and local density approximations - were used to model the influence of the chemical composition on the structural and electronic properties of the AlxIn1-xP system in the whole range of Al concentration x from 0 to 1. The band gap crossover from the direct to indirect band gap was shown to take place at x=0.406, in excellent agreement with the experimental result x=0.408 of Beaton et al. It was also demonstrated that the supercell-based calculations are better suited to describe variation of the composition-driven structural properties, whereas the virtual crystal approximation is better to be employed for the analysis of the electronic properties of the title system. (C) 2015 Elsevier Ltd. All rights reserved.