AIGaN/GaN two-dimensional electron gas metal-insulator-semiconductor photodetectors with sputtered SiO2 layers

GaN-based metal-insulator-semiconductor (MIS) two-dimensional electron gas ultraviolet (UV) photodetectors with sputtered SiO₂ insulation and passivation layers were fabricated. With a 5 V applied bias and 35 mW deuterium lamp irradiation, it was found that the photocurrent to dark current contrast ratio was 2.1 10⁴ for the MIS photodetector with passivation. It was also found that UV to visible rejection ratio of such MIS photodetector with passivation was more than three orders of magnitude, while the responsivity was 0.144 A/W with a 5 V applied bias and a 350 nm incident light wavelength. Such a result was found to be much larger than those observed from the metal-semiconductor-metal photodetector and the MIS photodetector without passivation.