Edge effects in pixelated CdZnTe gamma detectors

Edge effects in pixelated CdZnTe detectors occur due to the high dielectric constant of the CdZnTe detector material, and the tendency of the field lines emanating from the "hole" charge carriers to remain within the detector volume. As a result, spectra for edge and corner pixels tend to exhibit a longer low energy tail at the expense of the number of events in the photo-peak. We focus on a thick pixelated CdZnTe detector, where, the detector thickness is comparable to the lateral size. We develop a theoretical Monte-Carlo simulation that well describes the experimentally observed edge effects. We show that when the same detector is embedded in an array of similar detector at the same HV, the edge effects disappear, and the spectral properties the edge and corner pixels improve markedly.