Epitaxial growth and band offsets of β -(ScxGa1− x)2O3 thin films grown on (100) β -Ga2O3 substrate

β-(ScxGa1−x)2O3 (x = 0–0.36) thin films were epitaxially grown on (100) β-Ga2O3 substrates by oxygen-radical-assisted pulsed-laser deposition. β-(ScxGa1−x)2O3 epilayers were coherently strained up to x = 0.30, although the presence of a structural disorder was implied when x > 0.2. The bandgap energies measured by reflection electron energy loss spectroscopy increased from 4.56 to 5.25 eV with increasing Sc content. In β-(ScxGa1−x)2O3 epilayers, a slightly negative bandgap bowing behavior with a bowing parameter of −0.4 eV was observed, resulting in a larger bandgap increase than in β-(AlxGa1−x)2O3 epilayers with identical x. X-ray photoemission spectroscopy measurement revealed that the valence-band and conduction-band offsets of β-(Sc0.17Ga0.83)2O3 epilayer with respect to β-Ga2O3 were 0.0 and 0.3 eV, respectively.