Photoconductive and photovoltaic ultraviolet sensors based on GaN

We have fabricated photoconductive and photovoltaic ultraviolet sensors from GaN single layers and pn-junctions. These sensors exhibit a sharp long wavelength cut-off in responsivity at the bandgap (365 nm). The active layers (GaN) were deposited using low pressure MOCVD. The p-type doping was accomplished using Mg as the dopant. Photoconductive, and schottky barrier detectors were then fabricated using photolithography, reactive ion etching and contact metallizations. These processing techniques were developed specific to the A1xGa1-xN material system. We will discuss growth, fabrication and characterization details for these various device types. The measured values of device parameters will be contrasted with those estimated from active layer material characterization.