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

Abstract

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 × 10⁻¹⁹ A cm⁻². On illumination by a 0.36-μm 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 μm to 0.4 μm UV spectral range.