Band Offsets at β/γ-Ga ₂ O ₃ Interface: A Comprehensive Ab Initio and Experimental Investigation

Understanding band offsets at emerging self-organized β/γ-Ga2O3 interfaces is critical for their application in next-generation electronics. This work investigates the band offsets at two distinct β/γ-Ga2O3 interface orientations, considering both strained and relaxed states. We employed density functional theory calculations validated by high-resolution transmission electron microscopy and nanoscale strain analysis. Interfacial strain profoundly impacts the alignment, capable of inducing a Type-I to Type-II transition and yielding a large conduction band offset (CBO ≈ 0.35 eV) in the relaxed state. Furthermore, crystallographic orientation intrinsically modifies the offsets even in the absence of significant strain, demonstrating a distinct interface dipole effect. The large CBO predicted for the relaxed interface suggests the potential for high-density two-dimensional electron gas formation. However, the high strain sensitivity implies challenges due to relaxation, highlighting the need for controlled strain and orientation engineering for future polymorphic oxide devices.