Domain matching epitaxy of α-Ga 2 O 3 thin film on sapphire by pulsed laser deposition

Metastable (00 l )-oriented rhombohedral α-Ga 2 O 3 thin films with phase purity were epitaxially grown on c -plane α-Al 2 O 3 substrates using pulsed laser deposition. It was elucidated that domain matching epitaxy enables the epitaxial growth of α-Ga 2 O 3 thin film on α-Al 2 O 3 substrate by stabilizing structural instability through reducing misfit strain. In reciprocal space mapping analyses of α-Ga 2 O 3 thin films with different thicknesses, no considerable differences in lattice parameters ( a = 4.977 Å and c = 13.442 Å) and the degree of misfit strain were identified. The optical bandgap of α-Ga 2 O 3 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 α-phase. Our results provide a facile way to stabilize the metastable α-phase of Ga 2 O 3 using the α-Ga 2 O 3 /α-Al 2 O 3 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.