Investigation on the Neff reverse annealing effect using TSC/I-DLTS: Relationship between neutron induced microscopic defects and silicon detector electrical degradations

Neutron induced defect levels in high resistivity silicon detectors have been studied using a current-based macroscopic defect analysis system: thermally stimulated current (TSC) and current deep level transient spectroscopy (I-DLTS).These studies have been correlated to the traditional C—V I—V, and transient current and charge techniques (TCT/TChT) after neutron radiation and subsequent thermal anneals. It has been found that the increases of the space charge density, Neff in irradiated detectors after thermal anneals (Neff reverse anneal) correspond to the increases of deep levels in the silicon bandgap. In particular, increases of the double vacancy center (V—V and V—V− …) and/or Ci−Oi level have good correlations with the Neff reverse anneal. It has also been observed that the leakage current of highly irradiated (Φn > 1013 n/cm2) detectors increases after thermal anneals, which is different from the leakage current annealing behavior of slightly irradiated (Φn < 1013 n/cm2) detectors. It is apparent that V—V center and/or Ci—Oi, level play important roles in both Neff and leakage current degradations for highly irradiated high resistivity silicon detectors.