A new material for imaging in the UV: CVD diamond

We critically discuss the possibility of using diamond films, grown with the Chemical Vapour Deposition (CVD) technique, as imaging detector in the extreme UV energy range. We present results on electrical tests and on irradiation studies, under UV source, of CVD films, bought from market. We show that the behaviour of the film under irradiation in the energy interval of 190-350 nm would prevent its use as imaging detector, if special measures on the deposition qualities are not taken. We discuss the mechanisms of the behaviour under irradiation, in terms of the crystal defects. We have extensively studied the charge-up effect of the film and the influence on the detection efficiency. We find a dependence on the irradiation time and methods. We can address the explanation of the behaviour in terms of the decay time of the traps. This leads to an important conclusion on the homogeneity and on the defect sites. We claim that this effect depends on the defect types and it is rarely reproducible. (C) 2001 Elsevier Science B.V. All rights reserved.