BULK DAMAGE EFFECTS IN IRRADIATED SILICON DETECTORS DUE TO CLUSTERED DIVACANCIES

High resistivity silicon particle detectors will be used extensively i n experiments at the future CERN Large Hadron Collider. The detectors will be exposed to particle fluences equivalent to similar to 10(14) ( 1 MeV neutrons)/cm(2), causing significant atomic displacement damage. A model has been developed to estimate the evolution of defect concen trations and the electrical behavior of irradiated silicon detectors u sing Shockley-Read-Hall (SRH) semiconductor statistics, The observed i ncreases in leakage current and doping concentration changes can be de scribed well after Co-60-gamma irradiation but less well after fast ne utron irradiation. A possible non-SRH mechanism is considered, based o n the hypothesis of charge transfer between clustered divacancy defect s in neutron damaged silicon detectors. This leads to a large enhancem ent over the SRH prediction for V-2 acceptor state occupancy and carri er generation rate which may resolve the discrepancy between the model and neutron damage data. (C) 1997 American Institute of Physics.