CAREER: Towards rational design and control of oxygen migration in oxide thin films for nano-ionic technologies

该奖项的全部或部分资金来自《2021年美国救援计划法案》(公法117-2)。第1部分：非技术援助信息存储和数据处理传统上依赖于电子在不同材料之间的来回移动。相比之下，几项新兴技术依靠将氧离子移入和移出薄材料，通过改变材料化学来改变它们的性质，如电阻或磁性。后一种方法的预期优势包括更高的能效、更长的信息存储寿命，以及支持量子计算等新计算方法的能力。然而，准确测量非常薄薄膜中的氧扩散仍然具有挑战性，并在我们了解不同材料如何阻碍或促进小尺度氧离子运动的能力方面造成了瓶颈。这个职业项目由材料研究部的陶瓷项目支持，通过开发一种新的测量技术来解决这一瓶颈，该技术可以准确地测量通过不同薄膜堆叠的氧迁移，并从中提取关于每一层产生的氧迁移障碍和它们之间的界面的信息。然后，这些知识可以用来设计基于离子运动的技术，其精度与今天实现硅基电子产品的精度相同。此外，该项目的教育推广部分还制作了低成本的活动套件和免费培训视频，帮助K-12教师向学生介绍材料科学的概念，并向他们传授几种关键的电子设备。这些工具包得到了免费在线视频的支持，这些视频强化了活动概念，并将它们与正在进行的研究联系起来。这些经验有助于培养一批热情的年轻科学家，他们对材料科学原理以及如何利用这些原理创造更绿色的技术具有早期知识。第二部分：控制薄膜异质结构中纳米尺度的氧迁移对于利用强关联氧化物材料中发现的独特功能特性用于下一代信息技术非常重要。作为改善氧化物薄膜中离子迁移控制的一步，这一职业项目在材料研究部陶瓷计划的支持下，在纳米级离子扩散领域创造了新的测量能力和知识。具体地说，该程序开发了一种新的原位散射方法来量化氧浓度分布，并从不同的异质结构几何形状中提取定量扩散系数和激活能。将这种方法与薄膜工程技术相结合，可以分离出异质结构设计元素(例如应变、层厚度、层堆积)及其对原型钙钛矿结构中氧迁移的影响之间的单独结构-性能关系。通过将这些空间分辨散射研究与随温度变化的阻抗谱相结合，这项工作提供了在各种异质结构设计和温度范围内工作的主动扩散机制(S)的洞察。与这些研究工作相结合的是一项教育计划，该计划创建和分发电子材料活动套件，旨在支持国家学习标准，并由一个非专业观众视频数据库支持，该数据库将每个活动的核心思想与正在进行的研究联系起来。参与该项目的研究生获得了电子材料合成、最先进的表征方法以及与不同受众的科学交流方面的经验。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2).PART 1: NON-TECHNICAL SUMMARYInformation storage and data processing has traditionally relied on moving electrons back and forth between different materials. In contrast, several emerging technologies rely on moving oxygen ions in and out of thin materials to change their properties, like electrical resistance or magnetism, by changing the materials chemistry. The expected advantages of this latter approach include greater energy efficiency, longer information storage lifetimes, and the ability to support new computing approaches like quantum computing. However, accurately measuring oxygen diffusion in very thin films remains challenging and creates a bottleneck in our ability to understand how different materials hinder or facilitate oxygen ion movement at small length scales. This CAREER project, supported by the Ceramics program in the Division of Materials Research, addresses this bottleneck by developing a new measurement technique to accurately measure oxygen migration through stacks of different thin films and from that extract information about the barrier to oxygen migration created by each layer and the interfaces between them. This knowledge can then be used to design technologies based on ion motion with the same precision that enables silicon-based electronics today. In addition, the educational outreach component of this program creates low-cost activity kits and free training videos to help K-12 teachers introduce students to materials science concepts and teach them about several key electronic devices. These kits are supported by free online videos that reinforce the activity concepts and connect them to ongoing research. Such experiences help create a pipeline of enthusiastic young scientists with an early knowledge of materials science principles and how they can be used to create greener technologies. PART 2: TECHNICAL SUMMARY Controlling nanoscale oxygen migration in thin film heterostructures is important to harnessing the unique functional properties found in strongly correlated oxide materials for the next generation of information technologies. As a step towards improved ionic migration control in oxide films, this CAREER project, supported by the Ceramics program in the Division of Materials Research, creates new measurement capabilities and knowledge in the field of nanoscale ion diffusion. Specifically, this program develops a new in-situ scattering approach to quantify oxygen concentration profiles and extract quantitative diffusion coefficients and activation energies from different heterostructure geometries. Combining this approach with thin film engineering techniques enables the isolation of individual structure-property relationships between elements of the heterostructure design (e.g., strain, layer thickness, layer stacking) and their effect on oxygen migration in prototypical perovskite structures. By coupling these spatially resolved scattering studies with temperature-dependent impedance spectroscopy, this work provides insight into the active diffusion mechanism(s) operative in various heterostructure designs and temperature regimes. In conjunction with these research efforts is an educational plan that creates and distributes electronic materials activity kits designed to support state learning standards and are themselves supported by a database of lay-audience videos connecting core ideas from each activity to ongoing research. Graduate students engaged with the project gain experience in electronic materials synthesis, state-of-the-art characterization methodologies, and scientific communication to a variety of audiences.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.