EFRI 2-DARE: Enhancing Electronic and Thermal Properties in Epitopotaxial Ge/Sn Graphane Heterostructures

非技术：设计能够以可控方式定制电流和热量的新材料的能力对于解决现代科学技术的挑战至关重要。它对包括微电子、光电子和热电在内的许多领域都是必不可少的。二维（2D）分层材料为解决这一重要需求开辟了新的机会。虽然大量关于二维层状结构的研究都集中在二维碳晶体石墨烯上，但当前项目的目标将是制造和了解基于锗（Ge）和锡（Sn）的二维层状结构的性质。这些Ge/Sn石墨烯模拟结构提供了通过调整层数、组成层的化学成分和层之间可调的化学键来操纵电子、光学和热传输性质的可能性，并且在广泛的电子和热电应用中显示出巨大的前景。将建立最先进的材料合成，测量和理论建模方法，以了解如何调整石墨烯以外的二维材料中的电子和热输运。此外，我们将开发一种新颖的，可扩展的路线，将二维材料直接集成到现有的半导体生长和制造技术中。与该项目的主要研究目标相辅相成的是其更广泛的目标，其中包括努力加强参与机构的热科学教育，并提高当地社区对热科学前沿研究的重要性和兴奋性的认识。由于研究界与公众之间的互动不足，热科学常常被视为一个成熟的领域。最后，这种多机构合作将使研究团队能够共同努力，从多个科学和工程学科中代表性不足的群体中招募和留住学生。技术：该项目的总体研究目标是发展增强Ge/Sn石墨烯类似物耦合电子和热性能所需的基础知识，这是一个有前途的系统，可以通过使用不同的主族元素和不同的表面末端配体，在平面内和平面交叉方向上改变各向异性电子和热性能。为了实现这一目标，将开发一种新的、可扩展的合成方法，将Ge/Sn范德华异质结构直接集成到现有的半导体制造工艺中，通过将Ge（111）晶圆上的前驱体薄膜外延生长与它们的拓扑转换结合到范德华材料中。这些“外延”结构将有助于对单片、多层异质结构、大块2D晶体和不同衬底-2D界面的平面内和平面间电子、热电和热电性能进行全面的前沿测量。这些测量结果将反过来得到第一性原理理论计算的支持，以验证、预测和建立控制这些二维范德华异质结构材料的各向异性热和电子特性的基本原理。阐明在单层和多层二维范德华体系中控制各向异性热、电子和热电性能的关键机制将促进下一代电子和热电器件的发展。

Non-Technical: The ability to design new materials in which the flow of electricity and heat can be tailored in a controllable way is fundamentally important for addressing the challenges of modern science and technology. It is essential to numerous fields including microelectronics, optoelectronics and thermoelectrics. Two-dimensional (2D) layered materials open new opportunities for addressing this important need. While the vast amount of research on 2D layered structures has been focused on the 2D carbon crystal, graphene, the goal of the current project will be to fabricate and to understand the properties of 2D layered structures based on Germanium (Ge) and tin (Sn). These Ge/Sn graphane analogue structures offer the possibility to manipulate the electronic, optical and heat transport properties by adjusting the number of layers, chemical composition of constituent layers and tunable chemical bonding between layers, as well as showing great promise for a wide range of electronic and thermoelectric applications. State-of-the-art materials synthesis, measurements and theoretical modeling methodologies will be established for understanding how to tune electronic and thermal transport in 2D materials beyond graphene. Furthermore, we will develop a novel, scalable route towards integrating 2D materials directly into existing semiconductor growth and fabrication technology. Complementing the project's major research goals are its broader aims, which include efforts to enhance thermal science education in the participating institutions, and to increase awareness in local communities of the importance and excitement of cutting edge research in thermal sciences, which has often been perceived as a mature field because of insufficient interactions between the research community and the public. Finally, this multi-institutional collaboration will allow the research team to carry out a joint effort to recruit and retain students from underrepresented groups across multiple scientific and engineering disciplines.Technical: The overall research objective of this project is to develop the fundamental knowledge needed for enhancing the coupled electronic and thermal properties of Ge/Sn graphane analogues, a promising system that offers the ability to vary the anisotropic electronic and thermal properties along both the in-plane and cross-plane directions by using different main group elements and different surface-terminating ligands. To accomplish this, a novel, scalable synthesis method will be developed for the direct integration of Ge/Sn van der Waals heterostructures into existing semiconductor fabrication processes, by combining the epitaxial growth of precursor thin films on Ge(111) wafers with their topotactic conversion into the van der Waals material. These "epitopotaxial" structures will facilitate a comprehensive suite of cutting edge measurements of in-plane and cross-plane electronic, thermal, and thermoelectric properties of single sheets, multilayer heterostructures, bulk 2D crystals, and different substrate-2D interfaces. These measurements will in turn be supported by first-principle theoretical calculations to verify, predict and establish the underlying principles for controlling anisotropic thermal and electronic properties of these 2D van der Waals heterostructured materials. Elucidating the key mechanisms for controlling anisotropic thermal, electronic, and thermoelectric properties in single and multilayered 2D van der Waals systems will facilitate the development of next-generation electronic and thermoelectric devices.