Nuclear Instruments and Methods in Physics Research A 460 (2001) 127–137 A new material for imaging in the UV: CVD Diamond q L. Barberini, S. Cadeddu, M. Caria* Physics Department, University of Cagliari, 09042 Monserrato (Cagliari), Italy Abstract We critically discuss the possibility of using diamond films, grown with the Chemical Vapour Deposition (CVD) technique,asimagingdetectorintheextremeUVenergyrange.Wepresentresultsonelectricaltestsandonirradiation studies,underUVsource,ofCVDfilms,boughtfrommarket.Weshowthatthebehaviourofthefilmunderirradiation in the energy interval of 190–350nm 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 dependenceontheirradiationtimeandmethods.Wecanaddresstheexplanationofthebehaviourintermsofthedecay timeofthetraps.Thisleadstoanimportantconclusiononthehomogeneityandonthedefectsites.Weclaimthatthis effect depends on the defect types and it is rarely reproducible. # 2001 Elsevier Science B.V. All rights reserved. Keywords: Diamonds; CVD diamond; UV; Photodetectors; Electrical properties 1. Introduction Imaging in UV is of great importance for a very wide range of applications. As an example, researchers in the fields of biology investigate the bio-molecular compounds in the region of the energy spectrum they absorb the most. Their basic constituents always contains ATP which absorbs most in the interval 190–260nm [1]. The material which best suits imaging in UV is diamond. Its gap is 5.47eV corresponding to l=227nm. The advantage of using diamond in this interval is that, for a perfect material, there should be a sharp cut off, at wavelengths below and above this value. This would allow us to operate a UV imaging detector under room-light illumination or close to heating source, without deteriorated performance from infrared irradia- tion. The non-availability of pure diamond material in nature limits its use as a commercial imaging detector. We have investigated the possibility of using what is available on the shelf as synthetic diamond films grown with CVD techniques. Until now, these are the most studied [2] as radiation detectors and they are available in the market. In this paper, we report an investigation on the feasibility of using imaging detector based on CVD films. We have studied, in detail this behaviourunderrealisticconditionsofirradiation. We show that the composition of the material questions, the use of CVD diamond as UV imaging detector. We discuss the causes and special measures needed to suppress the effects, q Presented by Mario Caria. *Corresponding author. E-mail address: caria@ca.infn.it (M. Caria). 0168-9002/01/$-see front matter # 2001 Elsevier Science B.V. All rights reserved. PII:S0168-9002(00)01107-4