Electronic Excitation‐Driven β‐Ga ₂ O ₃ Metastability Transformation and Self‐Organization Mechanism: β→κ/γ/δ Phases

Abstract

Abstract Irradiation‐driven multiphase self‐organization presents emergent opportunities for the customization of nanoscale engineering properties, dynamically tuning strain‐field distributions and interfacial electronic structures. Responding to intense electronic excitation‐induced energy deposition, the dominant phase transformations, with varying Gibbs free energy , are confirmed as β → κ → γ → δ that are located in specific microregions for Gallium (III) oxide (Ga 2 O 3 ), as follows: (i) Surface‐localized interstitial accumulation under compressive stress triggers β → δ via semi‐coherent interface formation. (ii) Tensile stress within latent tracks drives vacancy‐mediated oxygen layer truncation (4/12 periodicity along ⟨0001⟩), stabilizing coherent 4H (ABCB) κ and 3C (ABC) β (ABC) interfaces through strain‐compensated octahedral distortion. (iii) Screw dislocation‐mediated lattice relaxation induces β → γ via cation disordering (Ga 3 ⁺ occupancy at β ‐interstitial sites), forming metastable spinel γ with mixed occupancy across 16d/8a Wyckoff sites. Irradiation‐driven β ‐Ga 2 O 3 → κ/γ/δ transitions, as mechanistically revealed via inelastic thermal spike (i‐TS) calculations and molecular dynamics simulations, induce defect‐mediated nonlinear photoresponse, critical for optoelectronic engineering.