Understanding and Modifying the Band Structure of Nano-Graphene Ribbons

本项目由电子与光子材料项目和凝聚态物理项目共同资助。非技术描述：超越经典的数字电子学到基于量子开关的器件是现代材料研究的目标。在碳化硅蚀刻沟槽上生长的石墨烯最近显示出令人难以置信的电子和磁性能，这可能为量子电子学提供一个新的平台。现在可以获得比理论预测最大值大100倍的电导率。然而，这些惊人特性的物理起源尚不清楚。该研究项目旨在了解亚50纳米石墨烯带的详细结构，并开发可重复生长和改变其电子特性的新方法。为近室温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。除了对技术产生影响外，该项目还将培养这一新领域的本科生，并教育高中科学教师，以便他们能够更好地就科学和工程专业的回报向学生提供建议。技术描述：最近有研究表明，生长在SiC沟槽侧壁上的石墨烯具有特殊的输运特性，其迁移率超过二维石墨烯的预测极限两个数量级以上[Nature 506, 349-354(2014)]。这些特殊性质所隐含的高度有序为石墨烯电子学的重大进步提供了机会。然而，这些条带中新型室温弹道传输的物理起源尚不清楚。该提案的目标是将石墨烯侧壁带的纳米结构与其测量的带结构联系起来。研究小组打算揭示应变、衬底键合和有限尺寸对这些独特条带的电子特性及其壮观的传输的作用。该团队使用了一套广泛的高分辨率表面敏感探针，使研究超越了单纯的输运实验，直接测量了它们的电子结构。采用高分辨率角度分辨光电发射技术测量其电子能带结构，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能带结构进行对比。

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.