Electronic properties of CVD polycrystalline diamond films

Electronic properties of polycrystalline diamond films have been analysed u sing steady-state photoconductivity under UV (lambda = 190 nm) and red (lam bda = 633 nm) illumination. We look at the effect of several post-depositio n treatments: annealing in vacuum at 400 degreesC, successive annealing und er air and methane or the reverse, and X-ray exposure. These are shown to a ffect the photoresponses in different manners. Globally, the mobility-lifet ime products of samples are found in the range 10(-7)-10(-6) cm(2) V-1 unde r W illumination, and ratios of photoresponses in W and red are in the rang e 10(3)-10(5). First results obtained using the modulated photocurrent tech nique are also presented. (C) 2001 Elsevier Science B.V. All rights reserve d.