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

Abstract

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 × 10-10 A/cm2 at 50 V bias, which is four orders of magnitude lower compared with devices on regular template. Device responsivities were 101.80 and 88.63 A/W at 50 V bias for 360 nm ultraviolet illumination for semi-insulating and regular templates, respectively. Incident power as low as 3 pW was detectable using the devices that were fabricated on the semi-insulating template. © 2006 American Institute of Physics.