Photoresponse Study of Polycrystalline Diamond thin Film Schottky Diodes

Abstract

We are reporting the first quantitative photoresponse characteristics of boron doped hot-filament CVD (HFCVD) diamond based Schottky diodes using semi-transparent aluminum contacts in the spectral range of 300–1050 nm. Quantum efficiencies, obtained without correction for surface reflection in the visible and near UV region, were between 5 % and 10% when the diodes were unbiased. Effect of reverse bias on the photoresponse was investigated at selected photon energies. Reverse biased diodes exhibit increasing photoresponse and ultimately saturation. Quantum efficiency as high as 30% was also obtained at 500 nm, when a reverse bias of over I volt was applied. The photoresponse mechanism of CVD diamond Schottky diodes is also discussed. A Schottky barrier height of 1.15 ± 0.02 eV for Al-HFCVD diamond contacts was determined using the d.c. photoelectric method.