Ga₂O₃ Schottky Avalanche Solar-Blind Photodiode with High Responsivity and Photo-to-Dark Current Ratio

Solar-blind photodetectors have attracted extensive attention due to their advantages such as ultra-low background noise and all-weather. In this study, the planar Ti/Ga₂O₃/Au Schottky avalanche photodetector (APD) is fabricated based on β-Ga₂O₃ epitaxial film on the sapphire substrate grown by metal–organic chemical vapor deposition. The Schottky APD exhibits a high responsivity of 9780.23 A W⁻¹, an ultrahigh photo-to-dark current ratio of 1.88 × 10⁷, an external quantum efficiency of 4.77 × 10⁶%, a specific detectivity of 9.48 × 10¹⁴ Jones, with an ultrahigh gain of 1 × 10⁶ under 254 nm light illumination at 60 V reverse bias, indicating high application potential for solar-blind imaging. The superior photoresponse performances ascribe to the effective carrier avalanche multiplication, which contributes to the high photocurrent, and the high quality Schottky junction depletion, which leads to the low dark current.