Performance Analysis of a Pt/n-GaN Schottky Barrier UV Detector

The electrical and optical characteristics of an n-type gallium nitride (GaN)-based Schottky barrier ultraviolet (UV) detector, where a platinum (Pt) metal layer forms the anode contact, have been evaluated by means of detailed numerical simulations considering a wide range of incident light intensities. By modeling the GaN physical properties, the detector current density-voltage characteristics and spectral responsivity for different (forward and reverse) bias voltages and temperatures are presented, assuming incident optical power ranging from 0.001 W cm(-2) to 1 W cm(-2). The effect of defect states in the GaN substrate is also investigated. The results show that, at room temperature and under reverse bias voltage of -300 V, the dark current density is in the limit of 2.18 x 10(-19) A cm(-2). On illumination by a 0.36-mu m UV uniform beam with intensity of 1 W cm(-2), the photocurrent significantly increased to 2.33 A cm(-2) and the detector spectral responsivity reached a maximum value of 0.2 A W-1 at zero bias voltage. Deep acceptor trap states and high temperature strongly affected the spectral responsivity curve in the considered 0.2 mu m to 0.4 mu m UV spectral range.