Band Alignment Engineering in β-Ga₂O₃/4H-SiC Polar Heterojunctions via Orientation Selection: Interfacial Band Edge States and Hole Trapping

The β-Ga₂O₃/SiC heterojunction exhibits significant application potential across multiple fields. This work systematically investigates the influence of β-Ga₂O₃ anisotropy and SiC polarity on interface characteristics by combining different surfaces and terminations of β-Ga₂O₃ with SiC polar faces. All models exhibit type-II band alignment with valence band offsets (VBOs) larger than 1.8 eV, which is suitable for photodetector applications. Contrary to polarity expectations, most Si-face models generally exhibit VBOs larger than those of their C-face counterparts. The observed anomalies arise from unsaturated C-O bonds within the C-face's interfacial six-membered-ring structure, which introduces band edge states at the interface. Holes from the β-Ga₂O₃ side will first occupy these states before transferring to SiC, leading to greater band upward shifting at the β-Ga₂O₃ side and consequently reduced VBOs. By revealing the origin and impact of the underlying mechanisms, this work provides a theoretical basis for band engineering in β-Ga₂O₃/4H-SiC heterojunctions.