Effects of hydrothermal temperatures on crystalline quality and photoluminescence properties of β-Ga2O3 microspheres using ammonia as a precipitator

Abstract

β-Ga₂O₃ microspheres were synthesized by a hydrothermal method. The products were characterized in detail to detect the effects of the hydrothermal temperature on their morphology, crystalline quality and photoluminescence properties. The lattice vibrational characteristics of the β-Ga₂O₃ samples were analyzed by Raman and far infrared spectroscopy. Ultraviolet (UV) photoluminescence was observed for the final β-Ga₂O₃ products. The emission peaks are observed in the blue-violet region between 350 and 450 nm and are greatly influenced by the hydrothermal temperatures. The blue-violet emission may be due to the trapped exciton, which is formed by the recombination of an electron in a donor level and a hole on an acceptor level. The weak UV peaks at around 250 nm are derived from the recombination of self-trapped excitons. The highest luminescence intensity of β-Ga₂O₃ is observed in the sample synthesized at 120 °C, which may be due to the highest defect concentration.