Radiation damage on p-type silicon detectors

Two sets of p-type silicon (high resistivity bulk and low resistivity epitaxial) samples and one set of n+–p junctions have been irradiated with fast neutrons up to 8×1013 cm−2. I–V and C–V characteristics as well as Thermally Stimulated Currents (TSC) and Hall Effect (HE) analyses have been performed on the irradiated samples and diodes in view to determine the radiation-induced damage and the change in the electrical properties. A change in the effective carrier concentration and in the leakage current after irradiation similar to the one found for p+–n detectors has been observed in p-type diodes. An increase with the fluence of the resistivity and Hall coefficient was measured at room temperature both for the low and high resistivity sets. This evidence has been explained in terms of a two-level model taking into account a linear increase in concentration with the fluence of the main radiation-induced defects observed with TSC, probably related to divacancy and carbon–oxygen complex.