Performance analysis of a Pt/n-GaN Schottky barrier UV detector

In this paper the electrical and optical characteristics of a n-type gallium nitride (GaN) based Schottky barrier ultraviolet (UV) detector, where a platinum (Pt) metal layer forms the anode contact, are evaluated by means of detailed numerical simulations considering a wide range of incident light intensities. With this purpose, by modeling the GaN physical properties, the detector current-voltage characteristics and spectral responsivity for different bias voltages (forward and reverse) and temperatures are presented assuming an incident optical power ranging from 0.001 to 1 Wcm-2. The effect of defect states in the GaN substrate is also investigated. The results show that, at room temperature, under a reverse bias voltage of -300 V, the dark current density is in the limit of 2.18×10-19 Acm-2. After illumination, for a 0.36 µm UV uniform beam with an intensity of 1 Wcm-2, the photocurrent significantly increases resulting 2.33 Acm-2 and the detector spectral responsivity attains a maximum value of 0.2 AW-1 at zero-bias voltage. Deep acceptor trap states and high temperature highly affect the spectral responsivity curve in the considered 0.2 - 0.4 µm UV spectrum.