Modulated electronic structure of β-Ga2O3/4H-SiC heterojunctions by polarization effect from first principles

While beta-gallium oxide/4H-silicon carbide (β-Ga₂O₃/4H-SiC) heterojunctions hold promise for high-performance and heat-dissipation-efficient high-power electronics, the atomic-scale mechanisms by which polarization effects govern interfacial charge dynamics and band alignment remain unresolved, limiting their performance optimization. Here, we employ first-principles calculations to systematically investigate six thermodynamically stable β-Ga₂O₃ (001)/4H-SiC (0001) heterojunction models with distinct atomic terminations. Formation energy (E_f) analysis reveals that oxygen-rich interfaces exhibit significantly enhanced thermodynamic stability, with the O-C and O-Si interfaces demonstrating formation energies of −0.419 eV/Ų and −0.603 eV/Ų, respectively, due to strong covalent bonding between O and C/Si atoms. Polarization-induced interfacial charge redistribution critically modulates internal electric fields (E_int) and band bending: Si-terminated interfaces exhibit electron depletion with E_int oriented from 4H-SiC to β-Ga₂O₃, while C-terminated interfaces show charge accumulation tendency and reversed E_int. Notably, β-Ga₂O₃ (001)/4H-SiC (0001) heterojunction exhibit type-I band alignments, with conduction band offsets (CBOs) of Si-terminated interfaces ranging from 0.47 to 0.76 eV, effectively suppressing electron leakage compared to C-terminated interfaces. These findings demonstrate a polarization-engineering strategy to design β-Ga₂O₃/4H-SiC heterojunctions with precisely electronic structure, thereby accelerating the development of β-Ga₂O₃-based power devices.