Collaborative Research: ARI-MA Development of Improved CMT and CZT Nuclear Detectors for Homeland Security Applications

该项目的目标是开发高分辨率碲化镉锰（CMT）和碲化镉锌（CZT）材料，用于国土安全中的核和放射性检测应用。这些材料已成为有前途的x射线和伽马射线光谱学和成像的先进探测器，无需低温冷却。研究的进步导致了用于商用设备的CZT的发展，但仍然存在碲（Te）夹杂物等缺陷，限制了核和放射性检测应用所需的大体积CZT和CMT探测器的性能。本项目的研究成果将造福社会，对用于国土安全（海上和港口安全、边境安全、交通安全、防扩散和国内核安全）的室温半导体核探测器科学技术产生重大影响。成果还包括新的能力，这些能力对于支持下一代核材料管理和保障所需的新兴探测技术和分析工具的成功非常重要。该项目促进发现和理解，同时促进教学、培训和学习。该项目团队将利用基于理论的设计、基于知识的加工和制造以及新颖的实验技术，开发用于高分辨率核探测应用的改进碲化镉锰（CMT）和碲化镉锌（CZT）材料。本项目将通过理论、建模和实验相结合的方法，提高该领域的科学水平，扩展该领域的整体知识，完成以下任务：1)优化Bridgman方法和旅行加热器方法（THM），以生长改进的CMT和CZT晶体；2)一种新的生长后退火和掺杂工艺，用于去除CMT和CZT探测器材料中碲夹杂物和相关杂质引起的性能限制缺陷；3)改进表面钝化和探测器制造技术，以生产更好的探测器。这些方法采用最先进的仪器，包括3d红外透射光谱和先进的测量工具，在生长后退火过程中探测和收集数据。用于监测晶体退火的原位工具的开发增加了一个新的实验维度，这将有助于提高对碲包裹体迁移的理解，并提供新的方法来最小化它们对电子俘获的影响。最终的结果将是CMT和CZT探测器具有更好的分辨率，提高检测效率和更好的方向灵敏度。本项目建模方面的结果将提供与三元II-VI化合物的Bridgman和THM生长相关的基本现象的理解，并提供有关生长后处理的建议，以改善这些晶体的微观结构特性。原位探测和数据收集技术的预期影响将包括对生长后退火的科学和动态特性的新见解，探测器材料的均匀掺杂，Te二次相和杂质的迁移，以及处理探测器表面的方法。该项目促进发现和理解，同时促进教学、培训和学习。它是多学科的，研究人员来自以下合作实体：阿拉巴马a&m大学，明尼苏达大学？双城，布鲁克海文国家实验室（BNL）， FLIR辐射公司，以及科学与工程研究和教育机会跨学科联盟（INCREASE）。该项目的劳动力发展部分将为妇女和代表性不足的少数民族提供机会，使其在发展尖端核与辐射探测技术的关键领域建立职业并获得研究生学位。

The goal of this project is to develop high-resolution Cadmium Manganese Telluride (CMT) and Cadmium Zinc Telluride (CZT) materials for nuclear and radiological detection applications in homeland security. These materials have emerged as promising advanced detectors for X-ray and gamma-ray spectroscopy and imaging without cryogenic cooling. Advances in research have led to the development of CZT for commercial devices, but there is still the presence of defects such as Tellurium (Te) inclusions that limit the performance of large-volume CZT and CMT detectors that are needed for nuclear and radiological detection applications. The results of this project will provide benefit to society, with high impact on the science and technology of semiconductor nuclear detectors for room-temperature applications in homeland security (maritime and port security, border security, transportation security, nonproliferation and domestic nuclear security). The outcomes also include new capabilities that are very important to the success of emerging detector technologies and analysis tools needed to support next-generation nuclear materials management and safeguards. This project advances discovery and understanding while promoting teaching, training, and learning.The project team will use theory-based design, knowledge-based processing and fabrication, and novel experimental techniques to develop improved cadmium manganese telluride (CMT) and cadmium zinc telluride (CZT) materials for high-resolution nuclear detection applications. The project will enhance the science and expand the overall knowledge in this area by using a combination of theory, modeling and experiments to complete the following tasks: 1) optimization of the Bridgman methods and Traveling Heater Method (THM) for growth of improved CMT and CZT crystals; 2) a novel post-growth annealing and doping process for removing performance-limiting defects caused by tellurium inclusions and associated impurities in CMT and CZT detector materials; and 3) improved surface passivation and detector fabrication techniques to produce better detectors. These methods employ state-of-the-art instrumentations that incorporate 3D-infrared transmission spectroscopy and advanced measurement tools to probe and collect data during the post-growth annealing process. The development of in-situ tools to monitor crystal annealing adds a new experimental dimension that will lead to any improved understanding of the migration of tellurium inclusions and novel methods to minimize their impact on electron trapping. The end result will be CMT and CZT detectors with better resolution, improved detection efficiency and better directional sensitivity. The outcomes from the modeling aspects of this project will provide an understanding of fundamental phenomena associated with Bridgman and THM growth of ternary II-VI compounds and suggestions regarding post-growth treatments to improve the microstructural properties of these crystals. The anticipated impact of in-situ probing and data collection techniques will include new insights into the science and dynamical properties of post-growth annealing, uniform doping of detector materials, migration of Te secondary phases and impurities, and methods to process detector surfaces. This project advances discovery and understanding while promoting teaching, training, and learning. It is multidisciplinary with investigators from the following collaborating entities: Alabama A&M University, University of Minnesota ? Twin Cities, Brookhaven National Laboratory (BNL), FLIR Radiation Inc, and the Interdisciplinary Consortium for Research and Educational Access in Science and Engineering (INCREASE). The workforce development component of this project will provide opportunities for women and under-represented minorities to build careers and earn graduate degrees in areas critical to the development of cutting-edge nuclear and radiological detection technology.