Atomic control of ionic processes in resistive memory devices

从制造业到社交网络，从大型组织到个人消费者，当今社会的方方面面都在不断产生大量数据，而且这一趋势正在加速延续。需要更好、更快的存储技术来快速高效地存储和分析数据。与此同时，传统的存储技术面临着基本的扩展限制和重大的实际限制，这使得跟上需求的挑战越来越大。该项目旨在开发一种全新的存储技术，通过在原子尺度上改变材料的内部结构来存储数据，从而显著提高设备性能。拟议的计划将显著推进基础科学研究，并加强对界面控制、离子和电子传输以及纳米级混合器件集成的理解。从NSF资助的这项计划中获得的结果也可能导致成功的技术转让，从而产生行业领先的存储产品，并对关键的半导体行业产生变革性的影响。该计划中开发的工具、方法和技术可应用于广泛的纳米设备和系统，以促进广泛领域的研究。该项目将为研究生和本科生提供跨学科培训，并吸引不同层次和背景的学生广泛参与合作研究和教育。建议的设备基于阻性随机存取存储器(RRAM)的概念，已显示出良好的可扩展性和其他几个性能指标。然而，该技术仍然面临着根本性的挑战，包括器件变化大、编程电流大、开关比小，这阻碍了该器件的实际应用。拟议的项目旨在实现对RRAM中电阻变化背后的基本离子过程的原子级控制，并生产具有显著性能改进和新器件功能的器件。具体地说，该器件利用原子薄的石墨烯作为离子阻挡层，通过石墨烯薄膜中纳米级的开口来调节氧空位(VO)的产生和迁移。通过控制掺杂，灯丝的形成将进一步限制在开关层内，以有利于VO的传输和存储的局域沟道。实验研究将得到理论计算和模拟的支持，包括预测VO形成能和O-O距离的第一性原理计算，以及预测VO分布和动态迁移过程的数值模拟。所提出的方法将消除开关层中过多的VO，并将显著改善RRAM器件的通断比、编程电流和器件变化性。同时，通过利用新兴材料和新兴设备的独特特性，拟议的项目推进了纳米设备研究的前沿，并自然促进了与物理、材料研究和设备工程的紧密结合。

Large amounts of data are being generated constantly in every aspect of today's society, from manufacturing to social networks, from large organizations to individual consumers, and this trend is continuing at an accelerated pace. Better and faster memory technologies are needed to store and analyze the data quickly and efficiently. At the same time, traditional memory technologies are facing fundamental scaling limits and major practical constraints that make it ever more challenging to keep up with the demand. This project aims to develop a fundamentally new memory technology that can store data by changing the material's internal configuration at the atomic scale, leading to significantly improved device performance. The proposed program will significantly advance fundamental scientific research and enhance the understanding of interface control, ionic and electronic transport and hybrid device integration at the nanoscale. Results obtained from this NSF-funded program will also likely lead to successful technology transfers that can result in industry-leading memory products, and have a transformative impact on the crucial semiconductor industry sector. The tools, methods and techniques developed in the program can be applied to a wide range of nanoscale devices and systems to stimulate research in a broad range of areas. The project will in turn provide interdisciplinary training of graduate and undergraduate students, and draw broad participation of students of different levels and backgrounds in collaborative research and education.The proposed device is based on the concept of resistive random-access memory (RRAM), which has shown excellent scalability and several other performance metrics. However, the technology still faces fundamental challenges, including large device variations, high programming current and small on/off ratio, which prevent the device from practical applications. The proposed project aims to achieve atomic-level control of the fundamental ionic processes underlying the resistance changes in RRAM, and produce devices with significant performance improvements and new device functions. Specifically, the proposed device exploits atomically-thin graphene as an ion-blocking layer to regulate oxygen vacancy (VO) generation and migration through nanoscale openings in the graphene film. The filament formation will further be confined inside the switching layer to localized channels that are favorable for VO transport and storage through controlled doping. The experimental studies will be supported by theoretical calculations and modeling, including first-principles calculations that predict the VO formation energy and O-O distance, as well as numerical modeling that predicts the VO distribution and dynamic migration processes. The proposed approaches will eliminate excessive VOs in the switching layer and will significantly improve the on/off ratio, programming current, and device variability of RRAM devices. In the meantime, by leveraging unique properties of emerging materials with emerging devices, the proposed project advances the frontier of nanoscale device research and naturally promotes a tight integration with physics, materials research and device engineering.