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

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 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)≃0.587x, and the conduction band offset scales with x in a nonlinear fashion. Quantitative comparisons to the corresponding experimental data are made.