Abstract
Atomic-scale phase transformations profoundly influence the functional properties of Ga₂O₃ polymorphs. By combining irradiation experiments with microstructure characterization and theoretical approaches, phase-specific energy-dissipation pathways in α-, β-, and ε-Ga₂O₃ are uncovered and strategies for targeted property design are outlined. Competing antiphase boundaries (APBs) and twin domain boundaries (TDBs) promote irreversible α→ε interconversion through domain fragmentation. In β-Ga₂O₃, defect-induced stress gradients drive two distinct local transformations: surface Ga-aggregated β→δ that stabilizes transient states, and latent-track-confined β→κ phase transition with recoverable distortions via cation reordering. Under electronic excitation, β-Ga₂O₃ forms nanohillocks via robust GaO₆ octahedra (high density/strong Ga─O bonds), while α/ε-Ga₂O₃ generates nanopores from tetrahedral Ga looseness (low bonding energy), highlighting phase-dependent surface dynamics shaped by atomic packing and bonding anisotropy. Defect-regulated recombination suppresses visible photoluminescence in α/β-Ga₂O₃, whereas in ε-Ga₂O₃ bandgap narrowing of ΔE: 0.30 eV is observed, enhancing emission. Linking phase-dependent defect-carrier interactions and metastable-phase engineering in Ga₂O₃ enables property optimization for power-electronics and optoelectronics devices.
