First results on the charge collection properties of segmented detectors made with p-type bulk silicon

Radiation damage of n-type bulk detectors introduces stable defects acting as effective p-type doping and leads to the change of the conductivity type of the silicon substrate (type inversion) after a fluence of a few times 10(13) protons cm(-2). The diode junction after inversion migrates from the original side to the back plane of the detector. The migration of the junction can be prevented using silicon detectors with p-type substrates. Furthermore, the use of n-side readout gives higher charge collection efficiency for segmented devices operated below the full depletion voltage. Large area 6.4 x 6.4 cm(2)) capacitively coupled 80 mum pitch detectors using polysilicon bias resistors have been fabricated on p-type substrates (n-in-p diode structure). These detectors have been irradiated with 24 GeV/c protons to an integrated fluence of 3 x 10(14) cm(-2) and kept for 7 days at 25degreesC to reach the broad minimum of the annealing curve. Results are presented on the comparison of their charge collection properties with detectors using p-sttip read-out after corresponding dose and annealing. (C) 2002 Elsevier Science B.V. All rights reserved.