Influence of metal properties and photodiode parameters on the spectral response of n-GaN Schottky photodiode

The spectral response of n-GaN Schottky photodiode is calculated for various metals including gold (Au), palladium (Pd), nickel (Ni) and platinum (Pt). The choice of the used metal is discussed. Responsivity increases with increase in the metal workfunction. A high light transmittance of the illuminated metal is recommended for not damaging the photoresponse. In order to achieve high performance, we also investigate the variation of spectral response and UV/visible contrast with parameters of the photodiode (doping density, layer thickness, etc.). A moderate doping level (10(18) cm(3)) and thin layer (0.5 mum) are needed to ameliore the responsivity and the rejection ratio. The application of reverse bias is effective to raise the photoresponse. The adequate choice of these parameters leads to a photodetector with the desired performance. (C) 2002 Published by Elsevier Science Ltd.