Band alignment and band offsets between (Al, Ga, In)BO₃ ultra wide bandgap materials

Ultra wide bandgap (UWBG) materials are promising for next-generation high-power electronics due to their capability to sustain large electric fields, exhibit high breakdown voltages, and operate efficiently at high temperatures. Achieving their full potential, however, requires a detailed understanding of band alignment and offsets between materials. In this work, we present a first-principles study of band alignment and offsets between the members of (Al, Ga, In)BO₃ ternary oxides, a group of materials family recently proposed for power electronics application. Their ionization energies, electronic affinities, resulting alignments of their electronic structures are evaluated using combined density functional theory surface calculations and bulk GW calculations. The band offsets are computed using the explicit interface models between each pair of compounds. In addition, all calculations are performed for varying strain bounded by the lattice constants of individual materials. Our analysis reveals the higher conduction band offset between GaBO₃ and InBO₃, when InBO₃ is strained to the in plane lattice parameters of GaBO₃ compared to inverse situation, suggesting favorable band alignment for charge confinement and potential HEMT-like behavior for InBO₃ films grown on GaBO₃ substrate.