Collaborative Research: Understanding Cross-plane and In-plane Transport in 2D Layered Heterostructures

合作研究：了解二维层状异质结构中的跨平面和面内传输

• 批准号: 1905185
• 负责人: David Johnson
• 金额: $ 23.31万
• 依托单位: University of Oregon Eugene
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-06-15 至 2022-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1905185&HistoricalAwards=false
• 关键词: Collaborative; Research; Understanding; Cross; plane

The goal of this collaborative effort is to develop an understanding of thermal and thermoelectric transport in an important new class of two-dimensional (2D) crystalline materials. This class of materials has the lowest thermal conductivities ever observed in a fully dense material. Highly efficient thermoelectrics can provide efficient solid-state cooling that rivals conventional refrigeration systems. This effort leverages measurement techniques recently developed in the Cronin lab, which enable the cross-plane (i.e. in the direction perpendicular to the layers) thermal and thermoelectric transport of extremely thin films to be measured accurately for the first time, and the unique materials synthesis capabilities developed in the Johnson lab, which enable specific sequences of 2D layers to be prepared and structurally characterized. Together, the labs will address several open questions regarding the thermal and thermoelectric transport properties of this interesting materials system, such as how the arrangement of layers and density of interfaces impact the difference between in plane and cross plane transport properties. This proposal will explore thermal and thermoelectric phenomena in a unique class of materials poised between the amorphous and crystalline states and test potential device structures using novel measurement techniques. In addition to thermoelectric energy conversion, the proposed scheme of studying cross-plane transport can be applied to a wide range of other device systems, including LEDs, FETs, and RTDs, currently being investigated by other groups. The proposed heterostructure geometries open up new degrees of freedom in the cross-plane transport with independent control of electrons and phonons, which is essential for achieving efficient thermoelectric energy conversion devices. The proposed layered heterostructures will enable many parameters to be varied such as inter-material barrier height, band gap (across the semiconductor-semimetal spectrum), and charge density wave transitions over a wide range of compositions to optimize thermoelectric phenomena. These structures enable investigation of systematic structural changes that are not possible with traditional approaches, for example, atomically-sharp interfaces that are not lattice matched and metal/semiconductor superlattices with atomically abrupt interfaces.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.

这项合作的目标是加深对新型重要二维 (2D) 晶体材料中热和热电传输的理解。此类材料具有在全致密材料中观察到的最低导热率。高效热电材料可以提供与传统制冷系统相媲美的高效固态冷却。这项工作利用了克罗宁实验室最近开发的测量技术，首次能够精确测量极薄膜的跨平面（即垂直于层的方向）热和热电传输，以及独特的材料合成约翰逊实验室开发的功能，可以制备特定的二维层序列并进行结构表征。这些实验室将共同解决有关这一有趣材料系统的热和热电传输特性的几个悬而未决的问题，例如层的排列和界面的密度如何影响平面和跨平面传输特性之间的差异。该提案将探索介于非晶态和晶态之间的一类独特材料的热和热电现象，并使用新颖的测量技术测试潜在的器件结构。除了热电能量转换之外，所提出的研究跨平面传输的方案还可以广泛应用于其他设备系统，包括 LED、FET 和 RTD，目前其他小组正在研究这些系统。所提出的异质结构几何形状在电子和声子的独立控制下开辟了跨平面传输的新自由度，这对于实现高效的热电能量转换装置至关重要。所提出的层状异质结构将使许多参数能够变化，例如材料间势垒高度、带隙（跨半导体半金属光谱）以及各种成分上的电荷密度波跃迁，以优化热电现象。这些结构能够研究传统方法不可能实现的系统结构变化，例如，不晶格匹配的原子尖锐界面以及具有原子突变界面的金属/半导体超晶格。该奖项反映了 NSF 的法定使命，并被认为是值得的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来提供支持。

项目成果

Predicting and Synthesizing Interface Stabilized 2D Layers

• DOI: 10.1021/acs.chemmater.1c01064
• 发表时间: 2021-06-23
• 期刊: CHEMISTRY OF MATERIALS
• 影响因子: 8.6
• 作者: Hamann, Danielle M.;Rudin, Sven P.;Johnson, David C.
• 通讯作者: Johnson, David C.