Tailoring light holes in β-Ga₂O₃ via Anion-Anion Antibonding Coupling

A significant limitation of wide-bandgap materials is their low hole mobility related to localized holes with heavy effective masses (mₕ^*). We identify in low-symmetric wide-bandgap compounds an anion-anion antibonding coupling (AAAC) effect as the intrinsic factor behind hole localization, which explains the extremely heavy mₕ^* and self-trapped hole (STH) formation observed in gallium oxide (β-Ga₂O₃). We propose a design principle for achieving light holes by manipulating AAAC, demonstrating that specific strain conditions can reduce mₕ^* in β-Ga₂O₃ from 4.77 m₀ to 0.38 m₀, making it comparable to the electron mass (0.28 m₀), while also suppressing STH. The light holes show significant anisotropy, potentially enabling two-dimensional transport in bulk material. This study provides a fundamental understanding of hole mass enhancement and STH formation in novel wide-bandgap materials and suggest new pathways for engineering hole mobilities.