Hydrogen-related 3.8 eV UV luminescence in α-Ga₂O₃

Temperature-dependent photoluminescence was used to investigate the impact of H on the optical properties of α-Ga2O3 films grown by halide vapor phase epitaxy. An additional UV luminescence line centered at 3.8 eV is observed at low temperatures, which strongly correlates with the concentration of H in the films. This luminescence line is assigned to donor–acceptor pair recombination involving an H-related shallow donor and H-decorated Ga vacancy (VGa-nH) as the acceptor, where n = 1, 2, 3. Previous reports have already suggested the impact of H on the electrical properties of Ga2O3, and the present study shows its clear impact on the optical properties of α-Ga2O3.