Modulated interfacial band alignment of β-Ga2O3/GaN heterojunction by the polarization charge transfer

Designing beta-Ga2O3/GaN heterojunction has been regarded as a promising approach to optimize the application of beta-Ga2O3. Here, band characters of beta-Ga2O3/GaN heterojunction are deeply understood by the polarization effect of GaN, which is vital to design high-performance beta-Ga2O3/GaN heterojunction. Due to the inconsistent band bending and orbital distribution induced by GaN polarization effect, just N-terminated beta-Ga2O3/GaN hetero-junction theoretically shows the type-II band alignment with two-dimensional electron gases (2DEGs). Such 2DEGs are just actually observed for N-terminated beta-Ga2O3/GaN heterojunctions with weak interfacial inter-action, but obvious interfacial energy barriers are found for heterojunctions with strong interfacial interactions which can weak the polarization charge transfer. The interfacial energy barriers can be turned into energy grooves upon introducing O-dopant with low concentration into the GaN region of heterojunction. In addition, all Ga-terminated beta-Ga2O3/GaN heterojunctions possess 2DEG band alignments, but abundant interfacial gap states are observed due to the lost electron of Ga atom from beta-Ga2O3 region and accumulated polarization electron of N atom from GaN region. In addition, band bending characters of beta-Ga2O3/GaN heterojunctions are negligibly dependent of the atomic arrangements of beta-Ga2O3 and GaN surfaces. These works deeply understand the interfacial performances of beta-Ga2O3/GaN heterojunctions and provide useful guidance for realizing high-performance beta-Ga2O3/GaN heterojunctions.