Contactless detection and analysis of electronic defects in CdZnTe

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CdZnTe is an emerging semiconductor alloy used in high energy x-ray detectors for medical diagnostics andsecurity applications. The performance of the detectors depends on controlling the density of electronicallyactive defects which trap charge generated by absorbed x-rays and act as recombination centres. The density ofdefects is affected by the crystal growth process and post growth processing of the crystals in ways that are stillpoorly understood. In order to improve the quality of the detector material and to reduce the cost ofmanufacturing detectors it would be desirable to have a fast contactless method for quantifying the density ofdefects and their chemical origin as well as for spatial mapping defects. Variable temperaturephotoluminescence (PL) is a contactless technique that can potentially satisfy these requirements. PL issensitive to low densities of defects, can probe small areas and can provide chemical specificity through theemission spectrum. In this project we will explore the applicability of PL for the routine assessment of theelectronic properties of device quality CdZnTe.