Temperature-dependence of X-ray excited luminescence of β -Ga₂O₃ single crystals

We investigated the temperature-dependence of X-ray excited luminescence of β-Ga₂O₃ single crystals. The recombination of free-electrons with self-trapped holes (STHs) responsible for the ultraviolet luminescence (UVL) band was observed. For the as-grown sample with a high electron concentration, the Auger recombination becomes important, which accelerates the decay dynamics and reduces the ultraviolet luminescence band. The ultraviolet luminescence band is controlled by temperature quenching due to the migration of self-trapped holes to V_Ga^3- centers. Annealing in an oxygen environment can increase the V_Ga^3- concentration, which contributes to the blue-green luminescence band when V_Ga^3- captures a self-trapped hole forming a V_Ga^2- center at rising temperature.