Electronic Pulse Shape Formation in Transient Charge and Transient Current Detection Approach in (CdZn)Te Detectors

The transient-charge technique (TChT) and transient-current technique (TCT) belong to basic methods routinely used for the determination of transport properties of semiconductor radiation detectors. In spite of apparently definite correspondence between the charge and current transients via simple differentiation or integration in time, the passing of the signal through real electronic circuits interferes with the evaluation of the transients and hampers the direct relation between TChT and TCT transients. In this paper we use in parallel both TChT and TCT for the characterization of (CdZn)Te detector and compare their output. We show how real TChT and TCT signals deviate from their ideal shape and complicate the evaluation of electron mobility from detected pulses. We conclude that whilst TCT may conveniently be used for the analysis of current waveforms and determination of carrier transit time and mobility in rather highly biased detectors, TChT is mainly useful for determining the total charge collection both at high and low biasing. We also suggest the way to improve the transit time readout in case of TChT method.