Time development and flux dependence of neutron-irradiation induced defects in silicon pad detectors

1×1 cm2 silicon pad p+–n–n+ detectors were irradiated with fast neutrons from the TRIGA research reactor in Ljubljana to fluences from 5×1013 to 1014n/cm2. The observed time development of annealing of the full-depletion voltage (FDV) could be fitted by a constant and two exponentials. The characteristic time of the fast component is 4 h, independent of temperature in the interval 0–15°C. A comparison of MESA and planar pad detectors shows a 20–30% lower FDV for the MESA. A search for a flux dependence of the radiation damage was performed in the range from 2×108 to 5×1015 n/cm2s and no systematic differences were observed.