CZT Semiconductors: Growth, atomic-level properties, and integration in X-ray detectors

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CdZnTe (CZT) semiconductors are currently the subject of extensive investigations as the material of choice for future generations of radiation detectors used in health care and security applications. Indeed, CZT detectors can deliver clear signals due to their stronger interaction with radiation, and their efficient generation and collection of charge carriers. These attributes, related to CZT higher average atomic number and its relatively large bandgap, provide a promising path to address the current limitations in X-ray detection technologies where, for instance, cryogenic cooling is typically required to limit the thermally generated noise, which makes these detectors bulky, expensive to acquire and maintain, and impractical for portable applications. However, exploiting this potential still faces major challenges as it requires high purity, low-defect, and homogenous semi-insulating crystals. These prerequisites are yet to be satisfied in commercial detector-grade CZT crystals, which typically suffer high concentrations of defects including Te-rich inclusions, dislocations, and twin- and subgrain-boundaries. These imperfections limit the efficiency and hinder the uniform and controlled large-scale production of detectors. This project aims at tackling these challenges by introducing new experimental and theoretical tools to investigate the atomic-level properties of CZT crystals and establish their role in shaping the behavior of photogenerated charge carriers. These fundamental aspects must be solved to reap substantial benefits at the forefront of new socio-economic and social opportunities. The proposed research will contribute to developing expertise and know-how of great relevance to the future needs of semiconductor technologies, training highly qualified personnel in high demand by academia and industry, and increasing the global competitiveness of Canadian universities and industries.