Fast neutron radiation damage effects on high resistivity silicon junction detectors

P+-n--n+ silicon radiation detectors made of high resistivity Si material (ρ ≥ 2 kΩ-cm) were irradiated to a neutron fluence of a few times of 1013 n/cm2. Dependence of detector leakage current, reverse bias capacitance, and effective doping concentration of the Si substrate on the neutron fluence have been systematically studied. It has been found that the detector leakage current increases linearly with neutron fluence in the range studies, with a damage constant of α = 9 x 10-17 A/cm (ΔI = αVΔφn), and the C-V characteristics of detectors irradiated to φn > 1012 n/cm2 become frequency dependent. Models using several defect levels in the band gap are proposed to describe the frequency dependent C-V effects and the electrical field profiles after high neutron fluence irradiation