Persistent photocurrent and surface trapping in GaN Schottky ultraviolet detectors

GaN-based Schottky detectors were implemented and their photoresponse as a function of the incident power and time was measured. The measured photoresponse shows gain saturation and persistent photoconductivity behavior. These effects are shown here to be related to each other, arising from a nonideal semiconductor surface. A microscopic model of the gain mechanism to explain these observations is presented. Trap density at the semiconductor metal interface, characteristic lifetime, and carrier capture coefficient are extracted from our measurements.