Band offset of GaAs/AlxGa1-xAs heterojunctions from atomistic first principles

TL;DR

This paper uses atomistic first principles calculations to accurately determine the band offsets in GaAs/AlxGa1-xAs heterojunctions across all Al doping levels, providing insights into their electronic properties.

Contribution

It introduces a combined approach using the coherent potential method and a semi-local exchange potential to predict band offsets with high accuracy.

Findings

Valence band offset scales linearly with Al concentration x.

Conduction band offset varies nonlinearly with x.

Calculated band gaps agree well with experimental data.

Abstract

Using an atomistic first principles approach, we investigate the band offset of the GaAs/AlxGa1-xAs heterojunctions for the entire range of the Al doping concentration 0<x<=1. We apply the coherent potential approach to handle the configuration average of Al doping and a recently proposed semi-local exchange potential to accurately determine the band gaps of the materials. The calculated band structures of the GaAs, AlAs crystals and band gaps of the GaAs/AlxGa1-xAs alloys, are in very good agreement with the experimental results. We predict that valence band offset of the GaAs/AlxGa1-xAs heterojunction scales with the Al concentration x in a linear fashion as VBO(x)~0.587 x, and the conduction band offset scales with x in a nonlinear fashion. Quantitative comparisons to the corresponding experimental data are made.