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

目前，作为用于医疗保健和安全应用的下一代辐射探测器的首选材料，镉锌Te(CZT)半导体是广泛研究的对象。事实上，CZT探测器可以提供清晰的信号，因为它们与辐射有更强的相互作用，以及它们有效地产生和收集电荷载流子。这些属性与CZT较高的平均原子序数及其相对较大的带隙相关，为解决目前X射线探测技术中的局限性提供了一条有希望的途径，例如，通常需要低温冷却来限制热产生的噪声，这使得这些探测器体积庞大，获取和维护成本高昂，并且不适用于便携式应用。然而，开发这一潜力仍然面临着重大挑战，因为它需要高纯度、低缺陷和均匀的半绝缘晶体。这些先决条件尚未在商业探测器级CZT晶体中得到满足，这种晶体通常存在高度集中的缺陷，包括富Te夹杂物、位错以及孪晶和亚晶界。这些缺陷限制了探测器的效率，阻碍了探测器的均匀和受控的大规模生产。该项目旨在通过引入新的实验和理论工具来研究CZT晶体的原子级性质，并确定它们在塑造光生电荷载流子行为中的作用，以应对这些挑战。必须解决这些基本方面，以便在新的社会经济和社会机会的前沿获得实质性利益。拟议的研究将有助于开发与未来半导体技术需求密切相关的专业知识和技术诀窍，培养学术界和工业界高需求的高素质人才，并提高加拿大大学和行业的全球竞争力。

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.