Band Alignment of β-Ga2O3 with BaTiO3, SrTiO3, and Related Composites

Abstract

Integrating perovskite oxides BaTiO3 (BTO), SrTiO3(STO) with β-Ga2O3 is of great interest for developing β-Ga2O3 power devices due to its promotion for improving uniformity in the electric field profile and breakdown characteristics. In this work, β-Ga2O3/BaTiO3 (BTO), β-Ga2O3/SrTiO3 (STO), β-Ga2O3/Ba0.5Sr0.5TiO3 (BSTO) heterojunction were epitaxially grown on sapphire substrates by low-pressure chemical vapor deposition (LPCVD) and radio frequency physical vapor deposition (RF PVD). The energy band alignment of β-Ga2O3/BaTiO3, β-Ga2O3/SrTiO3, β-Ga2O3/Ba0.5Sr0.5TiO3 (BSTO) heterojunction have been analyzed by X-ray photoemission spectroscopy and UV–visible transmittance spectrum. The conduction band offsets (∆E c ) of β-Ga2O3/BTO, β-Ga2O3/STO, β-Ga2O3/BSTO is found to be 0.32 ± 0.05, 1.15 ± 0.05, 0.78 ± 0.05 eV, respectively; and the valence band offsets (∆E v ) of these heterojunction is 0.76 ± 0.05 eV, 0.55 ± 0.05 eV, and 0.73 ± 0.05 eV, respectively. Our results indicate that type-I band alignment respectively form at these heterojunction, in which the valence and conduction bands of β-Ga2O3 are concomitantly higher than those of BTO, STO, and BSTO. The accurate determination of ∆E c and ∆E v is important for the design of β-Ga2O3/ferroelectric heterojunction multifunctional devices.