探测器级CdZnTe晶体中微观结构缺陷形成机制与表征方法

II-VI族化合物半导体因其可调的能带结构而展现出特殊的光电效应。其中CZT晶体是目前用于制备室温辐射探测器的理想材料。然而生长态的CZT晶体往往存在大量的微观结构缺陷，成为制约该材料发展的核心问题。本项目拟以熔体法生长的CZT晶体为研究对象，探索晶体中结构缺陷的表征方法，揭示其形成机制，发展其控制方法。主要内容包括：(1)发展并建立对CZT晶体中点缺陷（Cd空位、Te反位、杂质原子等）、线缺陷（位错）、体缺陷（Te沉淀与夹杂相）等微观结构缺陷的综合定量描述方法；(2)结合数值计算和热力学及动力学分析，研究晶体中微观结构缺陷的形成过程和机理，揭示微观结构缺陷动态演变规律和转化关系；(3)建立多种微观结构缺陷耦合作用对晶体物理性能的影响规律，揭示决定CZT晶体光电性能的主要因素。本项目通过对CZT晶体中微观结构缺陷的表征和形成机制研究，为有目标的进行晶体缺陷控制提供理论依据和技术路线。

II-VI compound semiconductors possess variable optoelectronic properties in a wide area due to their tunable band structures. For instance, Cadmium Zinc Telluride (CdZnTe, CZT), a typical II-VI compound crystal, has been considered as the most promising candidate for room temperature radiation detectors. However, as-grown CZT crystals usually contain plenty of microstructure defects, which hamper the adoption of state of the art devices. In this project, CZT crystals grown by melt method will be investigated. The main research proposals are as follows: (1) Quantitative characterization methods and techniques will be founded for microstructure defects, such as point defects (Cd vacancies, Te antisites, impurity atoms and so on), line defect (dislocations) and micro bulk defects (Te precipitates and inclusions); (2) The formation and evolution mechanisms of microstructure defects will be proposed according to the simulation and thermodynamic and kinetic analyses. The coupling effects and conversion of microstructure defects will be interpreted in terms of the thermodynamic equilibrium conditions. (3) The correlation between microstructure defects and the optoelectronic properties of CZT crystal will be confirmed. This project will offer new ideas for the modification of CZT crystals, through evaluating the formation and examining the behaviors of the microstructure defects.