GaN Based UV Sensors for Earth Resources Management

The purpose of the proposed work is to develop a multi-color imaging array capable of simultaneously detecting radiation in either the UVa (400-320nm) and UVb (320-290nm), or UVa (400-320nm) and UVc (290-100nm) wavelength bands. This will be the first such device ever fabricated. Imagers of this type can identify and track rocket trajectories even in bright sunlight. Many types of camouflage material are transparent in the UV, allowing for ordinance detection beneath camouflage. Earth resource management (crop data acquisition and weather prediction) will also benefit from this activity. Our research team has fabricated a single-color GaN imaging array. We found that bright solar radiation does create a significant background signal that makes missile plume identification difficult. The solar spectrum provides well-defined intensity ratios of UVa, UVb and UVc radiation. Sensing simultaneously in two of the three bands allows for rejection of signals with the solar ratio signature. This significantly reduces the possibility of registering false positive alarms.