Electronic Excitation-Driven β-Ga2O3 Metastability Transformation and Self-Organization Mechanism: β→κ/γ/δ Phases

XQ Han and YL Li and ML Crespillo and E Zarkadoula and Y Liu and WX Mu and SJ Zhao and P Liu, ADVANCED MATERIALS (2025).

DOI: 10.1002/adma.202519259

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 beta -> kappa -> gamma -> delta that are located in specific microregions for Gallium (III) oxide (Ga2O3), as follows: (i) Surface-localized interstitial accumulation under compressive stress triggers beta -> delta 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) kappa and 3C (ABC) beta (ABC) interfaces through strain-compensated octahedral distortion. (iii) Screw dislocation-mediated lattice relaxation induces beta -> gamma via cation disordering (Ga3(+) occupancy at beta-interstitial sites), forming metastable spinel gamma with mixed occupancy across 16d/8a Wyckoff sites. Irradiation-driven beta-Ga2O3 ->kappa/gamma/delta transitions, as mechanistically revealed via inelastic thermal spike (i-TS) calculations and molecular dynamics simulations, induce defect-mediated nonlinear photoresponse, critical for optoelectronic engineering.

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