Characterization of silicon pixel detectors with the n/sup +//n/p/sup +/ and double-sided multiguard ring structure before and after neutron irradiation

Abstract

The lifetime of silicon detectors in I severe radiation environment at CERN LHC depends strongly upon careful detector design and material selection, due to the anticipated radiation-induced damage. We fabricated recently more radiation-tolerant CMS forward pixel sensorsi with new designs of silicon pixel detectors with the n+/n/p+ and doublesided multiguard ring structure. Electrical characterization of such devices was performed before and after irradiation to neutron fluences (1 MeV equivalent) up to 6x1014 n/cm2, measuring leakage current, potential distribution over the guard rings and full depletion voltage. Studies on the radiation hardness using oxygen-enriched silicon substrates are being presented separately [l].

Radiation damage effects in Si materials and detectors and rad-hard Si detectors for SLHC

“…Use of multi-guard ring system can redistribute the electric field over a larger distance along the detector edge, thus preventing break down along the detector edge at large bias voltages. The detector is thus operated at much larger biases than the initial full depletion voltage, and can tolerate larger radiation fluence before the detector is forced into partial depletion by radiation-induced negative space charge build up [51][52][53]. Figure 17 shows the breakdown characteristics of n + /p/p + Si detectors with different number of guard rings [53].…”