Performance of diamond-based photoconductive devices in the UV range

A detailed investigation of diamond-based UV planar photoconductors with interdigitated contacts is presented, analyzing in particular the influence of film morphology and texturing on device performance. Photoluminescence and photocurrent spectroscopies reveal a strong correlation between structural defects and detector selectivity, whereas impurities affect photocurrent yield mainly in highly oriented materials. Responsivity measurements show that diamond-based devices give the highest UV-visible discrimination in comparison to UV-enhanced Si- and GaN-based sensors. For lambda less than or equal to 225 nm, an almost linear photocurrent-light intensity relationship is observed, although, in a few cases, a superlinear dependence on illumination intensity is found. A theoretical model, capable of describing the observed field dependendence of photocurrent gain is presented, giving minority carriers lifetime and mobility in the range 0.1-1 ns and 10-300 cm(2) V-1 s(-1), respectively. (C) 1998 Elsevier Science S.A