ELECTRICAL-CONDUCTION AT LOW-TEMPERATURES IN HIGH-ENERGY SILICON DETECTORS BEFORE AND AFTER IRRADIATION WITH NEUTRONS

Electrical I-V characteristics, at temperatures T greater than or equa l to 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 si milar to 1.1 V appears for non irradiated and lowly irradiated samples (Phi < 10(14) n/cm(2)). Unlike these samples (Phi < 10(14) n/cm(2)), by irradiation with neutrons, at fluences Phi greater than or equal to 10(14) n/cm(2) a similar abrupt increase of current If, at a critical switching voltage V-s, is seen, This value V-s increases drastically with fluence Phi and for a value Phi = 5.9 x 10(14) n/cm(2) V-s = 400- 500 V. At T = 10 K and Phi = 5.9 x 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 doubl e injection controlled by partially filled traps.