Large Area, Robust GaN-Based Photocathodes for High-Efficiency UV and Cherenkov Light Detection

For most commercial applications ¿ such as flame and arc sensing, air and water purification, and combustion monitoring ¿ the requirements for ultraviolet (UV) light detection are adequately provided by commercially available GaN-based photodiodes. However, many UV photon-counting and imaging applications ¿ including Cherenkov light detection, space-borne astronomy, and UV spectroscopy ¿ demand much higher performance in detector sensitivity, speed, resolution, and noise level. This project will develop wide-bandgap GaN-based photocathodes for high-sensitivity visible-blind UV photodetectors and imagers. Phase I demonstrated the remarkable efficiency and stability of GaN-based photocathodes for UV detector and electron emitter applications. Device simulations were performed to determine potential new photocathode structures. Phase II will further improve reliability and reduce fabrication costs for the production of both high performance UV detectors and electron emitters, via the study of novel cesium-free GaN-based photocathode structures. Commercial Application and other Benefits as described by the awardee: High-performance UV photocathodes should provide a springboard to the commercialization of two products: an efficient electron emitter and a sensitive photodetector. These products should have commercialization potential for many applications, including UV imaging, spectroscopy, maskless electron lithography, and thin film metrology.