, Volume 5, Issue 3, pp 469-477,
Open Access This content is freely available online to anyone, anywhere at any time.
Date: 07 Jan 2010

On the Chemical Origin of the Gap Bowing in (GaAs)1−x Ge2x Alloys: A Combined DFT–QSGW Study

Abstract

Motivated by the research and analysis of new materials for photovoltaics and by the possibility of tailoring their optical properties for improved solar energy conversion, we have focused our attention on the (GaAs)1 x Ge2x series of alloys. We have investigated the structural properties of some (GaAs)1 x Ge2x compounds within the local-density approximation to density-functional theory, and their optical properties within the Quasiparticle Self-consistent GW approximation. The QSGW results confirm the experimental evidence of asymmetric bandgap bowing. It is explained in terms of violations of the octet rule, as well as in terms of the order–disorder phase transition.