Dopant Distribution, Motion, and Electrochemical Transfer in Resistive Switching Heterostructures

技术：基于氧化物的异质结构（金属-氧化物-金属）的电阻开关自20世纪60年代以来就已经被人们所知，并且最近（自2000年以来）经历了商业和科学兴趣的爆炸式增长，特别是对于非易失性电阻变化随机存取存储器。电阻开关可以定义为材料或异质结构能够（在电刺激下）在至少两个随时间稳定的电阻值之间可逆变化的过程。大多数提出的解释电阻开关的竞争机制是定性的，只有间接的观察支持。然而，它们几乎都涉及通过离子运动在氧化层中重新分配掺杂剂。该项目将以定量的方式询问金属-氧化物-金属异质结构中的电位和氧分布，量化氧化物内部和金属-氧化物界面上的氧运动，并开发一个预测计算模型，以三维方式捕获开关过程的动力学方面。所描述的综合研究和教育计划旨在理解、设计和生产适用于数据存储和逻辑器件的纳米级电阻开关。对异质结构内均匀离子再分布可以定量表征并最终优化电阻开关的假设的测试将进行研究。为了做到这一点，研究将确定附近的氧气分布，测量氧气交换率，并量化金属氧化物结和氧化物异质结附近的电势，这些都是由卡内基梅隆大学设计和制造的。各种表征方法，包括二次离子质谱，电子全息，扫描开尔文探针显微镜，扫描电化学显微镜，基于电容的方法，以及空间分辨二次离子质谱来询问离子的再分配和转移将被使用。研究人员将建立一个多维连续体水平的计算模型，描述电阻开关中的电化学转移和离子再分配，并将通过纳米级电阻开关金属-氧化物-金属器件的测试来验证这一模型，以适应未来的应用。非技术：该项目将通过为新型超高密度数据存储设备和可重构逻辑技术的设备设计和性能提供基础基础，产生广泛的社会影响。这些研究活动将通过实验室和计算研究、高级选修课程和大二水平的实验模块，影响不同群体的博士和本科生的教育。这门名为“缺陷相互作用：实现高级功能材料和器件”的新选修课将提供具体的例子，说明缺陷相互作用（如记忆电阻器界面附近/跨界面的点缺陷运动）如何在高级器件中起推动作用，包括电阻开关、电池、燃料电池和大功率电子器件。在二年级材料科学核心课程“材料的缺陷”中引入实验模块。它将向学生展示点缺陷在电化学材料中的行为。最后，pi将在一个国际研究会议上组织一个关于电阻开关的研究研讨会。

Technical: Resistive switching in oxide-based heterostructures (metal-oxide-metal) has been known since the 1960's and has experienced a recent (since 2000) explosion of commercial and scientific interest, particularly for nonvolatile resistance-change random access memories.Resistive switching can be defined as the process in which a material or heterostructure is able to reversibly change (under electrical stimulation) between at least two resistance values that are stable with time. Most of the competing mechanisms proposed to explain resistive switching are qualitative and have only indirect observational support. However, they nearly all involve the redistribution of dopants in the oxide layer through ion motion. The project will interrogate in a quantitative fashion the electrical potential and oxygen distribution in metal-oxide-metal heterostructures, to quantify the oxygen motion within the oxide and across the metal-oxide interface, and develop a predictive computational model that captures the kinetic aspects of the switching process in three dimensions. The integrated research and education program described aims to understand, design, and produce nanoscale resistive switches appropriate for data storage and logic devices. Testing of the hypotheses that uniform ion redistribution within a heterostructure can be quantitatively characterized and ultimately optimized for resistive switching will be studied. To do so the research will determine the distribution of oxygen near, measure the oxygen exchange rates across, and quantify the electrical potential near metal-oxide junctions and oxide heterojunctions, designed and fabricated at Carnegie Mellon. A variety of characterization methods, including secondary ion mass spectroscopy, electron holography, scanning Kelvin probe microscopy, scanning electrochemical microscopy, capacitance-based methods, and spatially resolved secondary ion mass spectroscopy to interrogate ion redistribution and transfer will be used. A multi-dimensional continuum level computational model will be developed that describes the electrochemical transfer and ion redistribution in the resistive switch, which will be verified by testing of nanoscale resistive switching metal-oxide-metal devices, appropriate for future applications.Non-Technical: This project will have a broad societal impact by providing the fundamental underpinnings to device design and performance in novel ultra-high density data storage devices and reconfigurable logic technologies. The research activities will impact the education of a diverse group of Ph.D. and Undergraduate students through: laboratory and computational research, an advanced elective course, and a sophomore-level laboratory module. The new elective course, entitled 'Defect Interactions: Enabling Advanced Functional Materials and Devices,' will provide concrete examples of how defect interactions (such point defect motion near / across interfaces in memristors) act as enablers in advanced devices, including resistive switches, batteries, fuel cells, and high power electronics. A laboratory module will be implemented in the sophomore level core materials science course 'Defects in Materials.' It will demonstrate to students how point defects behave in electrochemical materials. Finally, the PIs will organize a research symposium on resistive switching at an international research conference.