Electronic properties of CVD polycrystalline diamond films

Electronic properties of polycrystalline diamond films have been analysed using steady-state photoconductivity under UV (lambda = 190 nm) and red (lambda = 633 nm) illumination. We look at the effect of several post-deposition treatments: annealing in vacuum at 400 degreesC, successive annealing under air and methane or the reverse, and X-ray exposure. These are shown to affect the photoresponses in different manners. Globally, the mobility-lifetime products of samples are found in the range 10(-7)-10(-6) cm(2) V-1 under W illumination, and ratios of photoresponses in W and red are in the range 10(3)-10(5). First results obtained using the modulated photocurrent technique are also presented. (C) 2001 Elsevier Science B.V. All rights reserved.