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的碲化锰镉(CMT)和碲锌镉(CZT)材料，用于国土安全中的核和辐射检测应用。这些材料已经成为X射线和伽马射线光谱和成像的有希望的先进探测器，而不需要低温冷却。研究的进步导致了用于商业设备的CZT的发展，但仍然存在诸如碲(Te)夹杂物等缺陷的存在，这些缺陷限制了核和放射检测应用所需的大容量CZT和CMT探测器的性能。该项目的成果将造福社会，对用于国土安全(海上和港口安全、边境安全、运输安全、防扩散和国内核安全)室温应用的半导体核探测器的科学和技术产生重大影响。成果还包括对支持下一代核材料管理和保障监督所需的新兴探测器技术和分析工具的成功非常重要的新能力。这个项目在促进教学、培训和学习的同时促进了发现和理解。项目团队将使用基于理论的设计、基于知识的加工和制造以及新的实验技术来开发用于高分辨率核探测应用的改进的碲化镉锰(CMT)和碲化锌镉(CZT)材料。该项目将通过理论、建模和实验相结合的方式，提高这一领域的科学水平，扩大该领域的整体知识，以完成以下任务：1)优化Bridgman法和旅行加热法(THM)生长改进的CMT和CZT晶体；2)采用新的生长后退火和掺杂工艺，消除CMT和CZT探测器材料中Te夹杂物和相关杂质造成的性能限制缺陷；以及3)改进表面钝化和探测器制造技术，以生产更好的探测器。这些方法使用最先进的仪器，包括3D-红外透射谱和先进的测量工具，以探测和收集生长后退火过程中的数据。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，这将导致对碲包裹体迁移的任何更好的理解，并将其对电子捕获的影响降至最低的新方法。最终的结果将是CMT和CZT探测器，具有更好的分辨率、更高的探测效率和更好的方向灵敏度。本项目模拟方面的成果将提供对与三元II-VI化合物的Bridgman和THM生长相关的基本现象的理解，以及关于生长后处理以改善这些晶体的微结构特性的建议。原位探测和数据收集技术的预期影响将包括对后生长退火的科学和动力学性质、探测器材料的均匀掺杂、Te第二相和杂质的迁移以及探测器表面处理方法的新见解。这个项目促进了发现和理解，同时促进了教学、培训和学习。它是多学科的，调查人员来自以下合作实体：阿拉巴马农工大学、明尼苏达大学？双子城，布鲁克海文国家实验室(BNL)，FLIR辐射公司，以及科学和工程研究和教育机会跨学科联盟(RAINT)。该项目的劳动力发展部分将为妇女和代表性不足的少数群体提供机会，在对发展尖端核和辐射探测技术至关重要的领域建立事业和获得研究生学位。

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.