Effects of dislocation walls on the performance of cadmium telluride X-ray detectors

We investigate microstructural defects in a chlorine-doped cadmium telluride crystal (CdTe:Cl), to understand the relationship between defects and performance of CdTe-based radiation detectors. We produced a CdTe-based X-ray detector operating in integration mode. However, its response under irradiation shows the presence of non-uniformities in sensitivity and dark-current maps, which means heterogeneities in the charge carrier transport. Advanced characterization tools, such as Infrared (IR) transmission and reflection microscopy and diffraction topography, are used to bulk and surface investigations. A clear correlation is established between the distribution of linear defects, such as dislocations and sub-grain-boundaries, and localization of zones of maximum dark-current and photo-current in the sample.