Domain matching epitaxy of α-Ga2O3 thin film on sapphire by pulsed laser deposition

Metastable (00l)-oriented rhombohedral alpha-Ga2O3 thin films with phase purity were epitaxially grown on c-plane alpha-Al2O3 substrates using pulsed laser deposition. It was elucidated that domain matching epitaxy enables the epitaxial growth of alpha-Ga2O3 thin film on alpha-Al2O3 substrate by stabilizing structural instability through reducing misfit strain. In reciprocal space mapping analyses of alpha-Ga2O3 thin films with different thicknesses, no considerable differences in lattice parameters (a = 4.977 angstrom and c = 13.442 angstrom) and the degree of misfit strain were identified. The optical bandgap of alpha-Ga2O3 thin film was modulated with crystal quality from 4.75 to 5.3 eV in the thickness range from 4 to 49 nm, indicating the characteristics of alpha-phase. Our results provide a facile way to stabilize the metastable alpha-phase of Ga2O3 using the alpha-Ga2O3/alpha-Al2O3 heterostructures through domain matching epitaxy with comprehensive structural characteristics and a promising potential for bandgap tuning for power devices, sensors, and solar-blind deep-ultra-violet photodetectors.