Influence of growth temperature on the characteristics of β-Ga2O3 epitaxial films and related solar-blind photodetectors

High-quality (-201)-oriented beta-Ga2O3 thin films were epitaxially grown on c-sapphire substrates by pulsed laser deposition (PLD) at various substrate temperatures using a beta-Ga2O3 ceramic target. These films were then used to fabricate metal-semiconductor-metal (MSM) solar-blind photodetectors (PDs) based on an Au/beta-Ga2O3/Au structure. The crystal quality, atomic ratio of O/Ga, and bandgap of the beta-Ga2O3 films all increased with increasing growth temperature, causing the dark current and response time of the PDs to decrease dramatically. The PD based on the beta-Ga2O3 film grown at 700 degrees C exhibited the best performance, with a low dark current of 10.6 pA at 10 V and a high peak responsivity of 18.23 A/W (at 255 nm). Furthermore, the response time of the fabricated PD was fast (tau(rise): 0.062/0.379 s, tau(deacy): 0.058/0.663 s). These results represent the state-of-art performance in dark current for PLD-grown beta-Ga2O3-based MSM solar-blind detectors.