The influence of electron track lengths on the γ-ray response of compound semiconductor detectors

The charge-trapping effect in compound semiconductor γ-ray detectors in the presence of a uniform electric field is commonly described by Hecht׳s relation. However, Hecht׳s relation ignores the geometrical spread of charge carriers caused by the finite range of primary and secondary electrons (δ-rays) in the detector. In this paper, a method based on the Shockley-Ramo theorem is developed to calculate γ-ray induced charge pulses by taking into account the charge-trapping effect associated with the geometrical spread of charge carriers. The method is then used to calculate the response of a planar CdTe detector to energetic γ-rays by which the influence of electron track lengths on the γ-ray response of the detectors is clearly shown.