GaN and AlGaN(p)/GaN p-i-n ultraviolet photodetectors

UV-sensitive, visible-blind photodetectors have potential applications in solar astronomy, missile plume detection, and combustion monitoring. In these applications, one would like to detect the intrinsic UV emission in a background of intense visible radiation. A leading candidate for these tasks is a GaN-based photodetector. To date, the majority of the effort in exploiting this material system for UV detection has concentrated on GaN-based photoconductors which suffer from long decay times and dark current. GaN p-n junction detectors and Schottky junction detectors have also been reported recently. For high speed and low noise applications, p-i-n photodetectors are generally more desirable as they lack the negative attributes of photoconductors. In this letter, we report on the performance of GaN p-i-n photodetectors grown by reactive molecular beam epitaxy with ammonia as the nitrogen source.