Charge transport properties of single crystal CVD-diamond particle detectors

The charge transport properties of virgin and heavily irradiated intrinsic Single-Crystal CVD-Diamond Detectors (SC-CVD-DD) are discussed by means of the Transient-Current Technique (TCT), which proved to be a sensitive tool to detect the first changes of the detector's performance. Charge-carrier mobilities mu(c) = 1300-3100 cm(2)/V s, mu(h)=2400 cm(2)/V s and effective deep-trapping lifetimes tau(eff-h)=300-900 ns, tau(eff-e)=160-360 ns were measured in the non-irradiated state, decreasing slightly after irradiation by a fluency F > 10(13) p(26MeV) cm(-2). The carriers drift velocity remained almost unchanged after irradiation, indicating the creation of mainly neutral defects. After exposure to fluency above 10(16) p cm(-2) however, TC signals were not detectable with the available broadband electronics. A significant improvement was observed after annealing at 1000 degrees C, and almost complete restoration was obtained by priming with Sr-90-electrons. Optical absorption (OA) spectra confirmed the degradation of the detector performance after exposure to increasing particle fluencies, showing deviations from the intrinsic 'edge absorption' shape around 5.3 eV that was observed before irradiation. (c) 2006 Elsevier B.V. All rights reserved.