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Revealing the role of inhomogeneities and disorder in 2D materials: Correlating transport with spatial and electronic topography

揭示二维材料中不均匀性和无序性的作用：将传输与空间和电子拓扑关联起来

基本信息

批准号：
1709029
负责人：
Shawna Hollen
金额：
$ 45万
依托单位：
University of New Hampshire
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2017
资助国家：
美国
起止时间：
2017-07-01 至 2022-06-30
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1709029&HistoricalAwards=false
关键词：
Revealing role inhomogeneities disorder 2D

项目摘要

Non-technical AbstractTwo-dimensional crystals form a new class of materials with robust mechanical and electrical properties, primed to change the way we build electronic devices for computers, optical detectors, and chemical or biological sensors. However, because they are only a single crystalline layer (1-3 atoms thick), their properties are more sensitive to their immediate environment than their three-dimensional counterparts. Substrates that support the 2D crystal, and impurities introduced by processing or adsorbed from the air degrade the performance of the material, and threaten the success of applications. 2D crystals also present a challenge to our fundamental understanding of electronic transport in 2D: many of these materials clearly show metallic behavior, but this is in contradiction with a very well-known theory of 2D electron transport called weak localization. The goals of this project are to understand the impact of defects and disorder on device performance and to investigate the roots of metallic behavior in 2D crystals. The research team will use a combination of electronic transport measurements and atomic-scale imaging to determine how electrons behave in the presence of disorder in 2D crystals. This project is supporting the education and training of two graduate students and a number of undergraduate students. It also supports the development of the next generation of researchers through summer workshops at University of New Hampshire for high school through graduate students. The goal of the workshops is to lower the barrier to success in research through topics that give new researchers practical information and advice, opportunities to hear about the diversity of research happening on campus, and a chance to personally connect with peers and principle investigators.Technical Abstract2D crystals are very attractive for use in next-generation electronics because they are as thin as physically possible, mechanically flexible, and still have robust electronic properties including, in several cases, high carrier mobility. They also present an opportunity to reexamine our expectations for electronic transport in 2D: many of these materials clearly show metallic behavior, but localization theory predicts weak localization universally in 2D. This project investigates the existence and properties of a metal-insulator quantum phase transitions in 2D materials, specifically focusing on the role of disorder and inhomogeneities. The research team is using scanning tunneling microscopy/spectroscopy coupled with device-scale transport measurements to correlate transport properties with spatial inhomogeneities in 2D materials as they are driven into the insulating phase by tuning disorder and carrier concentration. The team aims to uncover the role of disorder and inhomogeneities in quantum metal-insulator transitions and also the importance of different types of disorder in 2D crystal-based devices.

二维晶体形成了一类新的材料，具有强大的机械和电气性能，准备改变我们构建计算机，光学探测器和化学或生物传感器的电子设备的方式。然而，由于它们只是一个单晶层（1-3个原子厚），它们的特性对它们的直接环境比它们的三维对应物更敏感。支撑2D晶体的衬底以及加工过程中引入或从空气中吸附的杂质会降低材料的性能，并威胁应用的成功。2D晶体也对我们对2D电子输运的基本理解提出了挑战：许多这些材料清楚地显示出金属行为，但这与一个非常著名的2D电子输运理论相矛盾，称为弱局域化。该项目的目标是了解缺陷和无序对器件性能的影响，并研究二维晶体中金属行为的根源。研究小组将使用电子传输测量和原子尺度成像的组合来确定电子在2D晶体中存在无序时的行为。该项目正在支助两名研究生和若干名本科生的教育和培训。它还通过在新罕布什尔州大学为高中到研究生举办夏季讲习班，支持下一代研究人员的发展。研讨会的目标是通过为新研究人员提供实用信息和建议的主题，降低研究成功的障碍，有机会了解校园内发生的各种研究，并有机会亲自与同行和主要研究人员联系。技术摘要2D晶体在下一代电子产品中的应用非常有吸引力，因为它们尽可能薄，机械灵活，并且仍然具有鲁棒的电子特性，在一些情况下包括高载流子迁移率。它们也提供了一个机会来重新审视我们对2D电子输运的期望：这些材料中的许多清楚地显示出金属行为，但局域化理论预测2D中普遍存在弱局域化。该项目研究二维材料中金属-绝缘体量子相变的存在和性质，特别关注无序和不均匀性的作用。该研究小组正在使用扫描隧道显微镜/光谱学与设备规模的传输测量相结合，将传输特性与2D材料中的空间不均匀性相关联，因为它们通过调整无序和载流子浓度而被驱动到绝缘相。该团队的目标是揭示无序和不均匀性在量子金属-绝缘体转变中的作用，以及不同类型的无序在二维晶体器件中的重要性。