Substrate effects on GaN photodetector performance

Solar-blind UV photodetectors have a number of applications including missile detection, flame sensing, and solar UV monitoring. The III-V nitrides are ideal for these applications due to their wide bandgaps, making detectors transparent to visible and infrared radiation. There have been several publications on photoconductive GaN detectors on sapphire substrates but the effects of defect density on device performance have not been investigated. In this paper we describe the operation of GaN detectors grown by MOCVD on sapphire, SiC, and thick HVPE GaN base layers and compare the device performance of the detectors on each of these substrates.