Understanding and Modifying the Band Structure of Nano-Graphene Ribbons

该项目由电子与光子材料计划和凝聚态物理计划共同资助。非技术描述：超越经典数字电子学到基于量子开关的设备是现代材料研究的目标。在碳化硅腐蚀的沟槽中生长的石墨烯最近显示出令人难以置信的电和磁性能，这可能为基于量子的电子产品提供一个新的平台。现在可以获得比理论预测的最大值大100倍的电导率。然而，这些令人惊叹的特性的物理起源尚不清楚。该研究项目旨在了解亚50纳米石墨烯薄带的详细结构，并开发新的方法来重复生长和改变其电子性能。为接近室温的量子交换网络开发这些石墨烯带的社会影响将产生深远的影响。除了对技术的影响，该项目还将培训这一新领域的本科生，以及教育高中科学教师，以便他们可以更好地建议学生科学和工程专业的奖励。技术描述：最近发现，生长在碳化硅战壕侧壁上的石墨烯具有特殊的传输特性，其迁移率比预测的二维石墨烯高出两个数量级以上[自然506,349-354(2014)]。这些特殊性质所隐含的高度有序性为石墨烯电子学提供了取得重大进展的机会。然而，这种新颖的室温弹道传输在这些带子中的物理起源尚不清楚。这项提议的目标是将石墨烯侧壁带的纳米结构与其测量的带结构相关联。研究小组打算揭示应变、基片结合和有限尺寸效应对这些独特的带子的电子性质及其壮观的传输的作用。该团队使用了一系列高分辨率的表面敏感探测器，使研究超越了单纯的传输实验，直接测量了它们的电子结构。利用高分辨率角度分辨光电子能谱测量了它们的电子能带结构，并与扫描隧道显微镜、低能电子显微镜和透射电子显微镜测量的带状结构进行了关联。

This project is co-funded by the Electronic and Photonic Materials Program and the Condensed Matter Physics Program.Non-technical Description: Going beyond classical digital electronics to devices based on quantum switches is a goal of modern materials research. Graphene grown on trenches etched in silicon carbide have recently shown incredible electronic and magnetic properties that potentially offer a new platform for quantum-based electronics. Conductivities 100 times larger than theoretical predicted maximums are now obtainable. However, the physical origin of these amazing properties is not yet clear. This research project aims to understand the detailed structure of sub-50 nanometer graphene ribbons and to develop new ways to reproducibly grow and alter their electronic properties. The societal impact of developing these graphene ribbons for near room-temperature quantum-switching networks would have far reaching impacts. In addition to the influence on technology, the project will train undergraduate students in this new field, as well as educating high-school science teachers so that they may better advise their students on the rewards of scientific and engineering professions.Technical Description: It has recently been shown that graphene grown on the sidewalls of SiC trenches has exceptional transport properties with mobilities exceeding predicted limits for 2-dimentional graphene by more than two orders of magnitude [Nature 506, 349-354 (2014)]. The high degree of order implied by these exceptional properties offers an opportunity to make significant advances in graphene electronics. However, the physical origin of the novel room-temperature ballistic transport in these ribbons is not understood. This proposal's goal is to correlate the nanostructure of the graphene sidewall ribbons with their measured band structure. The research team intends to uncover the role of strain, substrate bonding, and finite size effects on the electronic properties of these unique ribbons and their spectacular transport. The team uses a broad set of high-resolution surface sensitive probes that allow the research to go beyond transport experiments alone to directly measure their electronic structure. It employs high-resolution angle resolved photoemission to measure their electronic band structure and correlate those results with ribbon structure measured by scanning tunneling microscopy, low energy electron microscopy and transmission electron microscopy.