Low dark current metal-semiconductor-metal photodiodes based on semi-insulating GaN

Metal-semiconductor-metal photodetectors on semi-insulating GaN templates were demonstrated and compared with photodetectors fabricated on regular GaN templates. Samples were grown on a metal organic chemical vapor deposition system. Devices on semi-insulating template exhibited a dark current density of 1.96×10−10A∕cm2 at 50V bias, which is four orders of magnitude lower compared with devices on regular template. Device responsivities were 101.80 and 88.63A∕W at 50V bias for 360nm ultraviolet illumination for semi-insulating and regular templates, respectively. Incident power as low as 3pW was detectable using the devices that were fabricated on the semi-insulating template.