Computationally predicted electronic structure of β-Ga2O3(001)/NiO interface

β-Ga₂O₃ is a promising ultrawide bandgap oxide (E_g ~4.9 eV) due to its excellent n-type performance and the fact that high-quality single crystal can be grown from melt. However, no p-type doping has been realized for β-Ga₂O₃, preventing homoepitaxial p-n junction. Instead, heterojunction is needed and β-Ga₂O₃(001)/NiO heterojunction was recently shown to have better rectifying performance than β-Ga₂O₃/Ni Schottky diodes. Experimental J-V curves indicate the existence of interfacial states but their identities remain unclear. We approached this with computational studies on atomic details and electronic structure and identified three technical challenges. First, building atomistic models for β-Ga₂O₃/NiO is non-trivial and we addressed it via the atom-to-atom structure-matching algorithm recently developed by Therrin et al.[1]. Second, common DFT-based methods fail to capture the electronic structure of the whole heterojunction correctly at the same time. In this poster, we will show how HSE06+U can simultaneously reproduce the respective band gaps of β-Ga₂O₃ and NiO. Lastly, passivating such end surfaces requires further considerations than tetrahedrally coordinated semiconductors. With these challenges addressed, we predicted the differences in band edges, which are very different from values estimated using the electron affinity rule. In addition, our findings reveal potential interfacial defects and provide the basis for future improvement on its rectifying performance.