Measurements of the band alignment at coherent α-Ga2O3/Al2O3 heterojunctions

The band alignment at a coherent alpha-Ga2O3/Al2O3 heterointerface was evaluated by analyzing X-ray photoemission spectra for an alpha-Al2O3 film and an alpha-Ga2O3/Al2O3 multi-quantum wells grown coherently on sapphire substrates. The measured bandgaps of alpha-Ga2O3 and alpha-Al2O3 were 5.7 and 8.7 eV, and the conduction- and valence-band offsets were 2.7 and 0.3 eV, respectively. The smaller valence-band offset is attributed the large contribution of localized O 2p orbitals at the top of the valance band in the oxides. These results complete our understanding of the band alignment of the alpha-(AlxGa1-x)(2)O-3 system in conjunction with the previously reported band offsets at alpha-Ga2O3/(AlxGa1-x)(2)O-3 heterojunctions (0.1 <= x <= 0.8). (C) 2018 The Japan Society of Applied Physics