Bias-Enhanced Visible-Rejection of GaN Schottky Barrier Ultraviolet Photodetectors

Abstract

The bias-enhanced performance of visible-blind ultraviolet (UV) detection of GaN Schottky barrier diodes has been studied. The UV response of the Schottky diodes was found to be vastly amplified at elevated reverse bias, leading to the observation of the voltage-dependent gain arising from the defect-induced Schottky barrier lowering effect. In contrast, the visible light response of the GaN Schottky diodes shows insignificant voltage dependence because of the dominance of the internal photoemission absorption. Thus, the visible rejection ratio, defined as the responsivity of UV over visible range, can be greatly enhanced at high operating bias for the UV detectors based on the GaN Schottky barrier diodes. The observation has been supported by both experimental results and simulation data, and has been utilized to minimize the interference between the monolithically integrated GaN photodetectors and power light-emitting diodes (LEDs) in the present study of LED communication.