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：氧化物材料正在越来越多地用于电子和记忆设备中，并且该类别的材料的性能受到材料的化学计量计和材料结晶晶格中伴随的缺陷的强烈影响。在应用电压下的缺陷的重新分布会导致许多电容设备的故障，但是重新分布也可能导致独特的材料功能，例如电阻性切换，这正在作为未来的内存技术探索。该研究计划旨在了解应用电压下的点缺陷再分配过程的基本问题，重点是与较高维晶格缺陷的点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采用各种最先进的电子成像和光谱技术来研究应用偏置下缺陷的动态演变以及对材料电气性能的影响。技术细节：在应用电偏偏置下带电的晶格缺陷的迁移率可能具有功能性电媒体设备的影响很大。 例如，长时间DC偏置过程中点缺陷的重新分布负责基于氧化物的电容器的泄漏电流增强。 相反，电场引起的氧化物中的缺陷迁移会引起有用的设备属性，例如电阻性开关，该特性正在积极探索非易失性存储器。 拟议的研究的总体目的是对介观长度上的点缺陷分布进行现象学和动力学理解。 所提出的方法是对良好控制的模型材料系统金红石TIO2进行研究，这是初始缺陷化学状态，电极边界条件，脱位浓度和晶体学方向的函数。 实验方法通过局部化学计量和原子结构分析融合了电运输测量。 拟议的研究中基本科学的进步正在使下一代功能陶瓷的发展，该计划培训了最先进的电子显微镜和材料研究的研究生和本科生。