Performances of SI GaAs detectors fabricated with a new technology

The non complete charge collection efficiency observed in Semi-Insulating (SI) Gallium Arsenide (GaAs) particle detectors has been generally attributed to trapping effects. However most of the detectors analyzed in literature can only operate below the depletion voltage. We present a careful analysis of the output signal and of performances of SI GaAs detectors, operated below and above full depletion and irradiated with ²⁴¹Am α particles. When the detector is biased below full depletion the output signals are affected by the undepleted part of the detector itself, while, when the detector is operated above the full depletion, the output signals are only affected by trapping-detrapping of charge carriers. Trapping-detrapping effects are in agreement with the analysis of deep levels present in the detectors. An energy resolution of 1.1% has been achieved with an ²⁴¹Am α source