Preparation of CdZnTe Photon-Counting Detectors by CSS Method: Annealing Regulation in Te2 Atmosphere

The CdZnTe (CZT) photon-counting detector with energy discrimination capabilities is one of the primary development directions for future medical X-ray imaging. Over the past few decades, the melt growth method has been commonly used for preparing CZT photon-counting detectors. However, this method has a long growth cycle and high cost due to the difficulty in manufacturing defect-free large-area wafers. CZT single crystals grown by closed-spaced sublimation (CSS) vapor phase growth method are expected to enable effective cost reduction. In this study, epitaxial CZT crystals grown by the CSS method were annealed in a Te2 atmosphere, resulting in a significant enhancement of the detectors’ photon-counting performance. The research investigates the relationship between annealing temperature and carrier transport properties, as well as the regulation of deep-level defects in CZT crystals and their impact on photon-counting characteristics. The goal is to determine the optimal annealing temperature as an effective strategy for improving the performance of CZT epitaxial crystal detectors. We systematically analyzed the electrical properties of detectors, such as resistivity, leakage current, energy resolution, and carrier mobility-lifetime product, and developed a CZT photon-counting detector with a high counting rate of 2.87M CPS/mm2. The results offer valuable theoretical and experimental foundations guidance for enhancing the performance of CZT epitaxial crystal detectors.