Irradiated silicon detectors operated at cryogenic temperatures: the Lazarus effect

An increasing interest in the behaviour of silicon detectors at cryogenic t emperatures has been awakened by the discovery of the so-called Lazarus eff ect, namely the recovery of charge collection efficiency (CCE) by means of cryogenic cooling. We measured the CCEs of three single diodes previously i rradiated with different neutron fluences. The current-voltage characterist ic were measured at 300 and 77 K, showing that the low-temperature operatio n considerably decreases the steady-state current. This is also the case wh en a forward voltage bias is applied, which then becomes a suitable option. At 77 K, in the case of samples irradiated with 5 x 10(14) neutrons cm(-2) , the CCE is completely recovered. A third sample irradiated with 2 x 10(15 ) neutrons cm(-2) shows a 60% CCE at 250 V forward bias.