Band offsets of AlxGa1−xN alloys using first-principles calculations

Abstract

First-principles calculations are employed for the study of the band offsets of AlxGa1−xN alloys, taking into account their composition and atomic configuration. Specifically, the band offsets are obtained using PBE, PBEsol, Heyd, Scuseria, and Ernzerhof (HSE), and modified Becke–Johnson calculations, comparing the results and discussing the advantages and disadvantages of each functional. The band alignments are performed using the branch point energies of the materials as their common reference level. HSE calculations predict a valence band offset of 0.9 eV between GaN and AlN. Regarding the alloys, a conduction band edge bowing parameter of 0.55 eV and a practically zero bowing for the valence band edge is predicted on average. The different atomic configurations affect mainly the valence band edges, where deviations from linearity by more than 0.1 eV are observed.