Transient photoresponse of CVD diamond-based detectors in the time domain 10-9 s-103s

Transient photoresponse of CVD diamond-based detectors has been studied in the time domain 10(-9) s-10(3) s by both chopped-light and pulsed laser excitations. A broad distribution of response times over the whole investigated range is observed, related to the quasi-continuous distribution of gap states induced by structural defects and impurities. Very slow components between 1 and 10(3) s also reflect non-diamond phase content and can be modified by surface treatments. Response times in the range 100 ns-100 ms generally correspond to trapping processes at relatively deep states, but in very defected material they can be correlated to dispersive transit time contribution, as observed in amorphous materials. Under 7 ns pulsed excitation decay times shorter than 3 ns are observed in fastest detectors. Such times seem related to trapping processes at shallow states rather than to recombination at midgap states, which involves characteristic times shorter than 1 ns. (C) 1999 Elsevier Science S.A. All rights reserved.