Optimization of Growth Temperature of β-Ga₂O₃ Thin Films for Solar-Blind Photodetectors

Monoclinic gallium oxide thin films were deposited on c-plane sapphire substrates at various substrate temperatures ranging from 450 °C to 700 °C by radio frequency magnetron sputtering technology. X-ray diffraction results showed that the deposited β-Ga₂O₃ films were oriented at ( 2 ¯ 01) direction. As the substrate temperature increased, the intensity of β-Ga₂O₃ peaks increased and bandgap decreased accordingly. Metal/semiconductor/metal structured solar-blind photodetectors based on β-Ga₂O₃ thin films growing at various substrate temperatures had been fabricated. The growth temperatures of thin films had no obvious influence on dark current and response to 365 nm light illuminations. The photoelectric properties such as responsivity and response speed of the thin films to 254 nm light illuminations were growth temperature dependent. At an applied bias of 50 V, the photodetectors prepared with 450 °C grown film had the highest responsivity of 2.18 A/W, and the photodetectors prepared with 700 °C grown film had the shortest rising time of 0.95 s under 254 nm light illuminations.