Influence of temperature on the I-V and C-V characteristics of Si detectors irradiated at high fluences

Abstract Measurements of I - V and C - V characteristics of non-irradiated and irradiated silicon detectors, at fluences 1.2 × 10 13 n/cm 2 ≤ Φ ≤ 5.9 × 10 14 n/cm 2 , were made in forward and reverse bias at low temperatures. An abrupt increase of the value of forward current was found at given bias voltages V S . This value increases with increasing values of Φ. The capacitance was measured at reverse bias V R , at ω = 10 kHz, and at temperatures 10 K ≤ T ≤ 200 K. The capacitance is a function of applied reverse bias, but for a given critical temperature T c , it does not change any more and remains constant for all applied values of V R . This value of T c depends on Φ. For increasing Φ, the critical temperature T c increases, e.g. for a non-irradiated sample, T c = 20 K and for a sample irradiated at Φ = 5.9 × 10 14 n/cm 2 , T c = 150 K. The observed phenomena can be explained assuming a freeze-out of free carriers at very low T , and space-charge-limited current (SCLC) for the very low concentration of majority carriers.