Photocurrent Studies of Ultraviolet Detector Based on Gallium Nitride Epilayer

The properties of photoconductive blue and ultraviolet detector based on single crystal GaN epilayer grown on sapphire substrate by metalorganic chemical vapor deposition were investigated. The observed optical absorption edge of 3.39eV in optical transmission has been confirmed by the peak of 3.400eV in photoreflectance. The detectable energy span of the GaN device up to ultraviolet was obtained by photocurrent measurement. The dependence of the intensity of photocurrent on the chopper frequency in the measurement was studied, and an easy method was used to determine the response time as 0.4s.