Optimization of Growth Temperature of beta-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 degrees C to 700 degrees C by radio frequency magnetron sputtering technology. X-ray diffraction results showed that the deposited beta-Ga2O3 films were oriented at ((2) over bar 01) direction. As the substrate temperature increased, the intensity of beta-Ga2O3 peaks increased and bandgap decreased accordingly. Metal/semiconductor/metal structured solar-blind photodetectors based on beta-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 degrees C grown film had the highest responsivity of 2.18 A/W, and the photodetectors prepared with 700 degrees C grown film had the shortest rising time of 0.95 s under 254 nm light illuminations.