Synergetic Effect of Photoconductive Gain and Persistent Photocurrent in a High-Photoresponse Ga₂O₃ Deep-Ultraviolet Photodetector

In this work, a metal-semiconductor-metal (MSM) beta-gallium oxide (Ga2O3) photodetector (PD) was constructed by microprocessing techniques, including UV photolithography, liftoff, and ion beam sputtering. The beta-Ga2O3 thin film was deposited on a sapphire substrate by a metalorganic chemical vapor deposition method. In addition to the high-quality thin film, the PD showed a phototo-dark current ratio of 3.5 x 10(7), a photoresponsivity of 509.78 A/W, a specific detectivity of 8.79 x 10(14) Jones, an external quantum efficiency (EQE) of 2.5 x 10(5)%, and a linear dynamic range of 94.41 dB at 10 V with 254-nm UV light illumination. The PD photoconductive gain decreases with the incident light intensity and reaches up to 2490 under 2000 mu W cm(-2). Such high photoconductive gain due to recycling transport in the active layer may lead to persistent photocurrent. Together with high photoresponsivity and EQE, the substantial internal gain may well exist in the beta-Ga2O3 PD, suggesting a high deep-ultraviolet photoresponse for the beta-Ga2O3 MSM photodetector in this article.