Micro-scale 2D mapping of cadmium-zinc telluride strip detectors

We had begun a program to develop CZT-based detectors optimized for synchrotron radiation (SR) applications. We have made a large number of pixellated and strip detectors with each element having a performance similar to that of individual commercial detectors. On the macroscopic scale it seems very hard to find a systematic correlation between performance and material defects, probably because of local stoichiometry variations and other local disordering. In order to understand the factors limiting the energy resolution of CZT X-ray detectors, our efforts were directed to the area of material characterization and detector testing using the National Synchrotron Light Source (NSLS). NSLS provides us with a highly collimated high intensity X-ray beam, which is employed to perform micro-scale stoichiometry measurement using the SR beam to excite fluorescence and using the characteristic line intensities to measure concentration. Micron-scale detector performance mapping is performed to measure the correlation between microscopic defects and fluctuations in collected charge.