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

Abstract

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, N eff in irradiated detectors after thermal anneals ( N eff 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 C i−O i level have good correlations with the N eff reverse anneal. It has also been observed that the leakage current of highly irradiated ( Φ n > 10 13 n/cm 2) detectors increases after thermal anneals, which is different from the leakage current annealing behavior of slightly irradiated ( Φ n < 10 13 n/cm 2) detectors. It is apparent that V—V center and/or C i—O i, level play important roles in both N eff and leakage current degradations for highly irradiated high resistivity silicon detectors.