Characterization of high fluence neutron induced defect levels in high resistivity silicon detectors using a laser deep level transient spectroscopy (L-DLTS)

Abstract

Neutron irradiated high resistivity (4–6 kΩ-cm) silicon detectors in the neutron fluence ( Φ n) range of 5 × 10 11 n/cm 2 to 1 × 10 14 n/cm 2 have been studied using a laser deep level transient spectroscopy (L-DLTS). It has been found that the A-center (oxygen-vacancy, E c = 0.17 eV) concentration increases with neutron fluence, reaching a maximum at Φ n ≈ 5×10 12 n/cm 2 before decreasing with Φ n. A broad peak has been found between 200 K and 300 K, which is the result of the overlap of three single levels: the V-V − ( E c = 0.38 eV), the E-center (P-v, E c = 0.44 eV), and a level at E c = 0.56 eV that is probably V-V 0. At low neutron fluences ( Φ n < 5 × 10 12 n/cm 2), this broad peak is dominated by V-V − and the E-centers. However, as the fluence increases ( Φ n ≥ 5 × 10 12 n/cm 2), the peak becomes dominated by the level of E c = 0.56 eV.