Collaborative Research: Atomically thin topological insulators via confinement heteroepitaxy

合作研究：通过限制异质外延制备原子薄拓扑绝缘体

• 批准号: 2002741
• 负责人: Robert Wallace
• 金额: $ 30万
• 依托单位: University of Texas at Dallas
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-07-01 至 2024-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2002741&HistoricalAwards=false
• 关键词: Collaborative; Research; Atomically; thin; topological

Nontechnical DescriptionThe dawn of quantum computing is rapidly developing with the potential to completely transform the field of computation. However, current quantum computers based on superconductors, ions, or atoms are prone to error due to imperfections. The solution to this grand challenge is to use new, engineered materials which are inherently immune to these imperfections. However, key questions remain regarding how to make a material that integrates the demanding properties needed to achieve superior performance in a technologically relevant manner. The principal investigators have created a new method to make ultra-thin metals, and this project focuses on understanding the microscopic properties of such metals, specifically bismuth and lead. The investigators will evaluate the impact of thinning these materials down to just a few atoms thick to explore how their properties change when they are manipulated at the atomic-scale. Beyond the scientific impact, this collaborative project will provide interdisciplinary research training for underrepresented graduate students, to broaden participation in science and engineering programs. The project will also develop a unique industry/university consortium to impart the importance of safety in industrial and research settings. This will not only better train future scientists for post-graduate careers in industry, but will also improve safety preparedness in academia.Technical DescriptionThe creation of a quantum spin Hall insulator (QSHI) by reducing the dimensionality of a topological insulator from 3D to 2D could provide a unique, robust route to achieving topological superconductivity. This project will investigate the atomic-scale physical, chemical and electronic properties of 2D bismuth (Bi) and lead (Pb). Lead and bismuth exhibit very strong spin-orbit interactions, and exceptionally robust and easily accessible topological insulator properties that may enable the design of groundbreaking electronic devices with dissipationless spin currents, and the realization of Majorana bound states. Furthermore, these elements exhibit unconventional superconductivity, and could be combined with ferromagnetic materials, suggesting the possibility of creating a Pb-based topological superconductor. The investigators enable the study by synthesizing atomically thin, two-dimensional forms of these materials prepared via confinement heteroepitaxy (CHet) – a novel intercalation process that stabilizes 2D forms of 3D materials developed by the PIs. The SiC/graphene interface passivation is investigated before, during and after synthesis to understand how interface reconstruction can enable in-situ removal of the graphene cap for direct characterization access to the 2D-Bi and Pb. Additionally, removing the graphene cap enables direct functionalization of the 2D metal to explore how modifying the surfaces of 2D-Bi and Pb changes their underlying physical properties, including bonding and electronic character. Finally, the project is developing a mechanistic understanding of how the structure and interfacial interactions with SiC and graphene impact electronic structure of 2D-Bi and 2D-Pb and elucidate how they differ from thin films deposited by traditional methods.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.

非技术描述量子计算的曙光正在迅速发展，有可能彻底改变计算领域，然而，当前基于超导体、离子或原子的量子计算机由于缺陷而容易出错。解决这一重大挑战的方法是使用量子计算机。然而，关键问题仍然是如何制造一种材料，以技术相关的方式整合实现卓越性能所需的特性。 -薄的该项目的重点是了解此类金属的微观特性，特别是铋和铅。研究人员将评估将这些材料减薄至几个原子厚度的影响，以探索在原子水平下操纵它们时它们的特性如何变化。除了科学影响之外，该合作项目还将为代表性不足的研究生提供跨学科研究培训，以扩大对科学和工程项目的参与。该项目还将建立一个独特的行业/大学联盟，以宣传工业和工程安全的重要性。研究这不仅可以更好地培训未来科学家的工业研究生职业，还可以提高学术界的安全准备。技术描述通过将拓扑绝缘体的维度从 3D 降低到 3D 来创建量子自旋霍尔绝缘体 (QSHI)。二维可以提供一种独特、可靠的途径来实现拓扑超导性，该项目将研究二维铋 (Bi) 和铅 (Pb) 的原子级物理、化学和电子特性。铅和铋表现出非常强的自旋轨道相互作用，以及异常坚固且易于获得的拓扑绝缘体特性，可以实现具有无耗散自旋电流的突破性电子器件的设计，并实现马约拉纳束缚态。此外，这些元素表现出非常规的超导性，并且可以与铁磁材料结合，这表明创建基于铅的拓扑超导体的可能性研究人员通过合成原子薄的二维材料来实现这项研究。通过限制异质外延 (CHet) 制备这些材料的形式，这是一种稳定 PI 开发的 3D 材料的 2D 形式的新型插层工艺。在合成之前、期间和之后研究了 SiC/石墨烯界面钝化，以了解界面重建如何在- 原位去除石墨烯帽，以便直接表征 2D-Bi 和 Pb 此外，去除石墨烯帽可以实现 2D 金属的直接功能化，以探索如何修改 2D-Bi 和 Pb。 2D-Bi 和 Pb 的表面改变了它们的基本物理特性，包括键合和电子特性，最后，该项目正在从机理上理解 SiC 和石墨烯的结构和界面相互作用如何影响 2D-Bi 和 2D-​​Pb 的电子结构。并阐明它们与传统方法沉积的薄膜有何不同。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Passivation of III–V surfaces with crystalline oxidation

通过晶体氧化钝化 III–V 表面

• DOI: 10.1063/1.5126629
• 发表时间: 2021-03
• 期刊: Applied Physics Reviews
• 影响因子: 15
• 作者: Laukkanen, P.;Punkkinen, M. P.;Kuzmin, M.;Kokko, K.;Lång, J.;Wallace, R. M.
• 通讯作者: Wallace, R. M.