Field-Induced Point Defect Redistribution in Metal Oxides: Mesoscopic Length Scale Phenomena

金属氧化物中场致点缺陷的重新分布：介观长度尺度现象

• 批准号: 1132058
• 负责人: Elizabeth Dickey
• 金额: $ 48万
• 依托单位: North Carolina State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-09-15 至 2016-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1132058&HistoricalAwards=false
• 关键词: Field; Induced; Point; Defect; Redistribution

NON-TECHNICAL DESCRIPTION: Oxide materials are being used increasingly in electronic and memory devices, and the properties of this class of materials are strongly influenced by the material's stoichiometry and the concomitant defects in the material's crystalline lattice. The redistribution of defects under an applied voltage leads to failure of many capacitive devices, but the redistribution can also lead to unique material functionalities such as resistive switching, which is being explored as a future memory technology. This research program aims to understand fundamental issues of the point defect redistribution process under applied voltage, focusing on the interactions of point defects with higher dimensional lattice defects and the effects of the metallic electrodes. The program utilizes and trains students in a variety of state-of-the-art electron imaging and spectroscopy techniques to study the dynamic evolution of defects under applied bias and the implications for the material electrical properties. TECHNICAL DETAILS: The mobility of charged lattice defects under applied electrical bias can have far reaching ramifications for functional electroceramic devices. For example, the redistribution of point defects during prolonged DC biasing is responsible for leakage current enhancement in oxide-based capacitors. Conversely, electric-field-induced defect migration in oxides can give rise to useful device properties such as resistive switching, which is being explored aggressively for nonvolatile memory. The overall objective of the proposed research is to develop a phenomenological and kinetic understanding of point defect distribution at the mesoscopic length scale. The proposed methodology is to conduct studies on a well-controlled model material system, rutile TiO2, as a function of the initial defect chemistry state, electrode boundary conditions, dislocation concentration, and crystallographic orientation. The experimental approach couples electrical transport measurements with local-stoichiometry and atomic-structure analysis. The advancement of fundamental science in the proposed research is enabling to the development of next-generation functional ceramics, and the program trains both graduate and undergraduate students in state-of-the-art electron microscopy and materials research.

非技术描述：氧化物材料越来越多地用于电子和存储设备，此类材料的性能受到材料的化学计量和材料晶格中伴随缺陷的强烈影响。施加电压下缺陷的重新分布会导致许多电容器件失效，但这种重新分布也可能导致独特的材料功能，例如电阻开关，这正在作为未来的存储技术进行探索。该研究项目旨在了解施加电压下点缺陷重新分布过程的基本问题，重点关注点缺陷与高维晶格缺陷的相互作用以及金属电极的影响。 该计划利用并培训学生各种最先进的电子成像和光谱技术，以研究施加偏压下缺陷的动态演化以及对材料电性能的影响。技术细节：施加电偏压下带电晶格缺陷的迁移率可能对功能性电陶瓷器件产生深远的影响。 例如，长时间直流偏置期间点缺陷的重新分布是氧化物电容器漏电流增强的原因。 相反，电场引起的氧化物缺陷迁移可以产生有用的器件特性，例如电阻开关，人们正在积极探索非易失性存储器的电阻开关特性。 该研究的总体目标是对介观长度尺度上的点缺陷分布进行现象学和动力学理解。 所提出的方法是对控制良好的模型材料系统金红石 TiO2 进行研究，作为初始缺陷化学状态、电极边界条件、位错浓度和晶体取向的函数。 该实验方法将电传输测量与局部化学计量和原子结构分析结合起来。 拟议研究中基础科学的进步有助于下一代功能陶瓷的开发，该项目对研究生和本科生进行最先进的电子显微镜和材料研究方面的培训。