DEFECT KINETICS IN SILICON DETECTOR MATERIAL

A numerical model based on experimental data has been used to investig ate the evolution of atomic defects in high-resistivity detector mater ial during neutron irradiation to levels expected at the CERN LHC. The complexes V2O and V3O have been identified as candidates for deep-lev el acceptor states which give rise to experimentally observed changes in the effective doping concentration. The phosphorus dopant is remove d by production of VP centres but at a rate lower than previously hypo thesised and not fully, even after heavy irradiation. The importance o f initial oxygen and carbon impurity concentrations is demonstrated in determining the radiation tolerance of the detectors. A hypothesis fo r the long-term annealing behaviour via the thermal annealing of a tri vacancy (V-3) state during heavy-particle irradiation is modelled and shown to be a possible explanation of experimental observations.