Investigation of performance of semi-insulating GaAs detectors irradiated by high γ doses

We report here the preliminary results on liquid encapsulated Czochralski (LEC) semi-insulating (SI) GaAs detectors after γ irradiation. The detectors have been irradiated with 1.17 and 1.33 MeV photons from 60Co with doses up to 19.2 kGy. Total doses correspond to the photon flux by the order of 1013 γ/mm2 incident on the device. The detectors before and after exposure to various radiation doses have been characterised. The I–V characteristics for both polarities and pulse-height spectra versus voltage applied at the temperature of 295 K using 122 keV 57Co γ-source were measured. A significant increase of charge-collection efficiency after irradiation of detectors was observed.