Large-area solar-blind AlGaN-based MSM photodetectors with ultra-low dark current

Large-area metal–semiconductor–metal (MSM) solar-blind photodetectors with a device area of 5×5 mm2 have been fabricated on Al0.4Ga0.6N/AlN/sapphire epistructure. The photodetector exhibits ultra-low dark current density of 3.2×10−12 A/cm2 under 20 V bias and a corresponding breakdown voltage of up to 385 V. The solar-blind/ultraviolet rejection ratio of the photodetector is more than four orders of magnitude with a maximum quantum efficiency of 28% at 275 nm.