GW band structure of InAs and GaAs in the wurtzite phase

TL;DR

This study presents the first quasiparticle GW calculations of the wurtzite phase of InAs and GaAs, revealing increased band gaps compared to their zinc-blende counterparts, and addresses the impact of In 4d electrons on band structure.

Contribution

It introduces the first GW-based band structure calculations for the wurtzite phase of InAs and GaAs, including the effects of In 4d electrons and compares different computational approaches.

Findings

Wurtzite phase has larger quasiparticle gaps than zinc-blende.

In 4d electrons significantly influence band ordering in InAs.

Different GW calculation methods yield consistent band gap predictions.

Abstract

We report the first quasiparticle calculations of the newly observed wurtzite polymorph of InAs and GaAs. The calculations are performed in the GW approximation using plane waves and pseudopotentials. For comparison we also report the study of the zinc-blende phase within the same approximations. In the InAs compound the In 4d electrons play a very important role: whether they are frozen in the core or not, leads either to a correct or a wrong band ordering (negative gap) within the Local Density Appproximation (LDA). We have calculated the GW band structure in both cases. In the first approach, we have estimated the correction to the pd repulsion calculated within the LDA and included this effect in the calculation of the GW corrections to the LDA spectrum. In the second case, we circumvent the negative gap problem by first using the screened exchange approximation and then calculating the GW corrections starting from the so obtained eigenvalues and eigenfunctions. This approach leads to a more realistic band-structure and was also used for GaAs. For both InAs and GaAs in the wurtzite phase we predict an increase of the quasiparticle gap with respect to the zinc-blende polytype.