Special Issue Article

Nanoscale Research Letters

, Volume 5, Issue 3, pp 469-477

Open Access This content is freely available online to anyone, anywhere at any time.

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

  • Giacomo GiorgiAffiliated withDepartment of Chemical System Engineering, School of Engineering, University of Tokyo Email author 
  • , Mark Van SchilfgaardeAffiliated withArizona State University
  • , Anatoli KorkinAffiliated withArizona State University
  • , Koichi YamashitaAffiliated withDepartment of Chemical System Engineering, School of Engineering, University of Tokyo

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.

Keywords

Photovoltaics III–V IV-doped alloys Bandgap bowing Order–disorder phase transition DFT Quasiparticle Self-consistent GW