Low temperature annealing effects on the performance of proton irradiated GaAs detectors

Semi-insulating, undoped, Liquid Encapsulated Czochralski (SI-U LEG) GaAs detectors have been irradiated with 24 CeV/c protons at the fluence of 5.6x10(13) p/cm(2). The detector charge collection efficiency, cce, for both electrons and holes is remarkably reduced after irradiation while the reverse current increases. The effect of annealing the detectors at temperatures ranging from 220 degrees C to 280 degrees C has been seen to reduce the reverse current and to increase the electron cce, while the recovery of the hole cce is negligible in irradiated detectors. Deep electron traps have been followed in their evolution with the heat treatment temperature by P-DLTS and C-V measurements. They recover by increasing the heat treatment temperature and this can explain the restoration observed in electron cce.