ELEVATED-TEMPERATURE ANNEALING OF THE NEUTRON-INDUCED REVERSE CURRENTAND CORRESPONDING DEFECT LEVELS IN LOW AND HIGH-RESISTIVITY SILICON DETECTORS

A new aspect of degradation phenomena of neutron irradiated silicon de tectors has been revealed which consists in the significant influence of carbon related defect transformation on the detector reverse curren t (I-rev). The annealing of the reverse current at elevated temperatur es and the corresponding changes of the deep level transient spectrosc opy (DLTS) spectra of defects for fast neutron irradiated silicon dete ctors, fabricated on high (4-6) k Omega-cm, moderate (0.5-1.0 k Omega- cm) and low ( < 100 Omega-cm) resistivity silicon;material have been i nvestigated. For al resistivity silicon detectors studied in this work , three annealing stages of the defects with deep levels in the energy band gap have been observed: 1) the transformation of carbon related defects in the temperature range of 20-72 degrees C; 2) decrease of th e peak E(c) - 0.4 eV at 150 degrees C, and 3) complete annealing of th e peak E(c) - 0.4 eV at 350 degrees C. The transformation of carbon re lated defects consisted in the annealing of interstitial carbon (C-i) and simultaneous generation of C-i-O-i complex and was accompanied by a significant reduction of the reverse current. The decrease of the pe ak E(c) - 0.4 eV was observed in the temperature range of 72-350 degre es C and was affected by both the annealing of the E-center (V-P compl ex) and single minus charge state of divacancy (VV-) and by the change s in the filling of the deep levels in high or moderate resistivity Si . The results show the comparable role of the V-P complex and VV- cent er in formation of E(c) - 0.4 eV defect in high and moderate resistivi ty silicon.