Near valence-band electronic properties of semiconducting β-Ga2O3 (100) single crystals

beta-Ga2O3 is a transparent wide-band-gap semiconductor that has attracted considerable interest in recent years due to its suitable electrical conductivity and transparency in the ultraviolet spectral region. In this work we investigate the electronic properties of the near valence-band-edge region for semiconducting beta-Ga2O3 (100) bulk single crystals using core-level photoelectron spectroscopy and ab initio theory within the framework of density functional theory and the GW approach. We find good agreement between the experimental results and the theoretical calculations. This is explained by the hybridization of the Ga 3d and O 2s states, similar as for In2O3.