Band Offsets of the MOCVD-Grown β-(AlGa)O/β-GaO (010) Heterojunction.

The band offsets for the β-(AlGa)O/β-GaO (010) heterojunction have been experimentally measured by X-ray photoelectron spectroscopy. High-quality β-(AlGa)O films were grown by metal-organic chemical vapor deposition for characterization. The indirect band gap of β-(AlGa)O was determined by optical transmission to be 4.69 ± 0.03 eV with a direct transition of 5.37 ± 0.03 eV, while β-GaO was confirmed to have an indirect band gap of 4.52 ± 0.03 eV with a direct transition of 4.94 ± 0.03 eV. The resulting band alignment at the heterojunction was determined to be of type II with the valence and conduction band edges of β-(AlGa)O being -0.26 ± 0.08 and 0.43 ± 0.08 eV, respectively, above those of β-GaO (010). These values can now be used to help better design and predict the performance of β-(AlGa)O heterojunction-based devices.