A model of charge collection for irradiated p+n detectors

The charge collection in irradiated p(+)n silicon detectors was studied as a function of the reverse bias voltage. Oxygenated and non-oxygenated devic es were irradiated beyond type inversion with 24 GeV/c protons. The charge collection is successfully described with a model based on the hypothesis t hat the charge trapping depends on the carriers velocity. With this model. values for the full depletion voltage are extracted which show good agreeme nt with those measured using the CV technique. The model allows a quantitat ive understanding of why although oxygenation of p(+)n devices improves sub stantially the full depletion voltage, much less improvement is observed in the charge collection efficiency. (C) 2001 Elsevier Science B.V. All right s reserved.