Growth and Interface Physics of Epitaxial Graphene

该项目由材料研究部（DMR）的电子和光子材料（EPM）和凝聚态物理（CMP）项目共同资助。技术：本研究项目是关于碳化硅（SiC）衬底外延石墨烯的生长和界面物理。外延石墨烯是一种二维电子系统，其相干长度在4 K温度下可以超过1微米，并且即使在室温下也具有高电子迁移率。多层石墨烯以类似石墨的方式生长在碳化硅的硅端面上。在碳化硅的碳端面，多层石墨烯的生长更不寻常，从一个石墨烯层到下一个石墨烯层具有方位角旋转。这减少了石墨烯层之间的相互作用。然而，这种旋转堆积（和电子解耦）的起源是不确定的。利用表面科学方法（包括通过低温扫描隧道显微镜和相关技术进行表征），将开发和量化SiC上外延石墨烯的新生长方法。本项目将研究不同维数的石墨烯基材料界面的物理性质，以及石墨烯的固有性质。二维界面包括石墨烯/SiC界面、旋转石墨烯层之间的界面和金属/石墨烯界面。感兴趣的一维界面是石墨烯p-n结，其中一侧的电子载流子传输到另一侧的空穴态。研究了不同取向石墨烯晶格的一维（平面内）晶界的电子特性，以及阶梯边缘和光刻定义纳米带的电子特性。“零维界面”包括石墨烯和石墨烯量子点中的点缺陷。我们工作中最关注的量子点是由测量本身在石墨烯中诱发的势阱。非技术：这项研究涉及石墨烯的开发，这是一种潜在的应用于低功耗、纳米级电子设备的新材料。在这个项目中，石墨烯指的是单原子厚和少原子厚的碳薄膜。整个项目通过参与由教育专业人员设计的项目，将研究与不同层次的教育联系起来。这些项目通常侧重于培养传统上在物理科学领域代表性不足的学生。例如，乔治亚州的高中教师每年夏天通过教师校内研究体验项目在PI的实验室进行7-8周的研究体验。这种经历使他们能够把现代科学带到课堂上。

This project is co-funded by the Electronic and Photonic Materials (EPM) and Condensed Matter Physics (CMP) Programs in the Division of Materials Research (DMR).Technical: This research project is on the growth and interface physics of epitaxial graphene grown on silicon carbide (SiC) substrates. Epitaxial graphene is a two-dimensional electron system with coherence lengths that can exceed one micrometer at a temperature of 4 K, and with high electron mobilities, even at room temperature. Multiple layers of graphene grown on the silicon-terminated face of silicon carbide stack in a manner similar to graphite. On the carbon-terminated face of SiC, the growth of multiple layers is more unusual, with azimuthal rotation from one graphene layer to the next. This has the effect of reducing the interaction between graphene layers. However, the origin of this rotational stacking (and the electronic decoupling) is not known with certainty. Using surface science methods (including characterization via low-temperature scanning tunneling microscopy and related techniques), new growth methods for epitaxial graphene on SiC will be developed and quantified. The physics of interfaces of graphene based materials of different dimensionalities, as well as intrinsic graphene properties, will be studied in this project. Two dimensional interfaces include the graphene/SiC interface, the interface between rotated graphene layers, and the metal/graphene interface. A one-dimensional interface of interest is the graphene p-n junction, where electron carriers on one side transmit into hole states on the other. The electronic properties of one-dimensional (in-plane) grain boundaries separating graphene lattices with different orientation are also investigated, and likewise for step edges and lithographically-defined nanoribbons. "Zero-dimensional interfaces" comprise point defects in graphene and graphene quantum dots. The quantum dot of most concern for our work is a potential-well induced in graphene by the measurement itself.Non-Technical: This research concerns the development of graphene, a new material with potential applications to low-power, nanometer-scale electronic devices. In this project, graphene refers to one-atom-thick and few-atom-thick carbon films. The overall project ties research to education at different levels via participation in programs designed by education professionals. These programs often focus on the preparation of students traditionally underrepresented in the physical sciences. For example, Georgia high school teachers experience research in the PI's lab for 7-8 weeks each summer through an on-campus Research Experience for Teachers program. The experience enables them to bring modern science to the classroom.