Energy resolution in GaAs X- and γ-ray detectors

The present limits of the energy resolution achievable using GaAs detectors are analysed and discussed. The noise due to the reverse current and the noise due to the charge-carrier trapping have been considered, giving upper limits to attain specific energy resolutions. The degradation of the resolution due to charge trapping is examined. It is shown that, in general, a charge collection efficiency higher than 98% is required to reduce the influence of the trapping in high-resolution X- and γ-ray spectroscopy with GaAs detectors.