Annealing of defects in irradiated silicon detector materials with high oxygen content

A deep level transient spectroscopy (DLTS) study of electrically active defects in electron irradiated silicon detectors has been performed. Two types of materials have been studied and compared: carbon-lean magnetic Czochralski (MCZ-) Si, and high purity, diffusion oxygenated float-zone (DOFZ-) Si. In both materials we observed an earlier reported shift in position of peaks associated with the divacancy (V-2) at 250-325 degrees C, indicating a gradual transition from V-2 to the divacancy-oxygen complex (V2O). Heat treatments at higher temperatures reveal a difference in annealing behaviour of defects in DOFZ- and MCZ-Si. It is observed that VO and V2O anneal with a higher rate in DOFZ-Si. The appearance of a hydrogen related level only in the DOFZ-Si reveals a small presence of H and it is suggested that the difference in annealing behaviour is due to defect interaction with H in the DOFZ-Si. Our findings also suggest that dissociation may be a main mechanism for the annealing of V2O in MCZ-Si.