The effect of Te precipitates on characteristics of CdZnTe detectors

The effects of Te precipitates on the performances of CdZnTe nuclear radiation detectors were investigated with wide X-ray or alpha-particle beams. In these measurements, the degradations in the device performances were correlated with the areas of high concentrations of Te precipitates aggregated around the crystalline defects or with large-size (>100 μm) individual precipitates. The critical role of the small-size, 1-20 pm in diameter, precipitates was not clearly established, because of the large size of the particle beams used in prior studies (300-400-μm diameter). Our recent measurements conducted with a highly collimated, <10 μm, x-ray beam and thin, ∼1 mm, CZT crystals proved that even a single small-size precipitate affects the local charge transport properties in CdZnTe detectors. The next step is to determine the extent of the potential cumulative effect of randomly distributed Te precipitates on the properties of CZT detectors. In this work, we report on the modeling of the effects of Te precipitates on measurable characteristics such as energy resolution, detection efficiency, electron mobility-lifetime product, and others and compare with the experimental results.