Electrical conduction at low temperatures in high energy silicon detectors before and after irradiation with neutrons

Abstract Electrical I - V characteristics, at temperatures T ≥ 10 K, were studied. A drastic reduction of free carriers (freeze-out) was observed, due to cooling. An abrupt increase of I f at V f ∼ 1.1 V appears for non irradiated and lowly irradiated samples ( Φ 14 n / cm 2 ). Unlike these samples ( Φ 14 n / cm 2 ), by irradiation with neutrons, at fluences Φ ≥ 10 14 n/cm 2 , a similar abrupt increase of current I f , at a critical switching voltage V s , is seen. This value V s increases drastically with fluence Φ and for a value Φ = 5.9 × 10 14 n/cm 2 V s = 400–500 V. At T = 10 K and Φ = 5.9 × 10 14 n/cm 2 oscillations of I f occurred at voltages around V s . For higher temperatures, oscillations do not appear. These phenomena can be explained on the basis of double injection controlled by partially filled traps.