Photoresponse of CVD diamond films in the 100-300 nm spectral range

A set of CVD diamond films has been grown by the Microwave Plasma Enhanced Chemical Vapour Deposition (MPECVD) technique, systematically increasing the methane concentration in the gas mixture. The aim of the present work is to investigate the performances of photoconductive detectors based on these diamond films, when exposed to UV radiation. The analyzed spectral region is extended below the limit of 180 nm reported in other works, covering the 100-300 nm range. The dark current, photocunent and spectral response of the detectors have been examined and related to diamond crystal properties. In particular, the dependence of UV response on diamond crystal orientations shows that less oriented polycrystalline films have a better response than highly textured films. In addition, a comparison between detector performances in air and vacuum has been carried out both in planar and sandwich configuration of the electric contact.