Collaborative Research: Structure and Morphology of Graphene Sheets for Carbon-Based Nanoelectronics

石墨烯是单层碳原子，即使在室温下也表现出微米级的无耗散导电性。因此，石墨烯可以在硅基器件达到其自然极限的时候继续纳米电子学的小型化趋势。然而，石墨烯片的面积和质量的控制仍然是一个主要的挑战，因为它们的形态是由原子尺度的现象和表面特征的长程弹性相互作用决定的。在碳化硅上生长石墨烯的实验表明，生长大而光滑的石墨烯片的关键在于控制前体层的结构，即石墨烯与衬底之间的界面的结构。为了实现我们控制石墨烯片质量的主要目标，我们提出了一种多尺度方法，该方法将表面表征的实验技术与原子尺度计算、寻找表面结构的遗传算法以及成核和生长的连续模型相结合。如果成功，这项工作将指导新的方法来生长大而光滑的石墨烯片，其通过光刻图案化可用于制造低功率纳米电子器件。我们对前体层的结构和缺陷的调查将提供对载流子散射机制的深入了解，从而了解石墨烯基器件的性能。此外，我们将确定重建的前体层，特别适合作为模板的组装规则阵列的纳米结构，如富勒烯，金属簇，和功能分子。这项工作的各个方面将在科罗拉多矿业学院和布朗大学最近开发的课程中介绍。研究人员将积极参与职业咨询和学生辅导，并将利用这项研究的结果，以提高K-12数学教师和高中学生的经验下，材料研究科学与工程中心在布朗的推广计划。

Graphene, a single-layer of carbon atoms, exhibits dissipation-free electric conduction over the scale of microns even at room temperature. As such, graphene could enable the continuation of the miniaturization trend in nanoelectronics at a time when silicon-based devices reach their natural limitations. However, the control over the area and quality of graphene sheets remains a major challenge because their morphology is determined both by atomic-scale phenomena and by long-ranged elastic interactions of surface features. Experiments on graphene growth on silicon carbide show that the key to grow large and smooth graphene sheets lies in controlling the structure of the precursor layer, i.e. of the interface between graphene and the substrate. To achieve our primary objective of controlling the quality of graphene sheets, we propose a multi-scale approach that combines experimental techniques for surface characterization with atomic-scale calculations, genetic algorithms for finding the surface structure, and continuum models of nucleation and growth.If successful, this work will guide novel approaches to grow large and smooth graphene sheets, which through lithographic patterning can be used to fabricate low-power nanoelectronic devices. Our investigations of the structure and the defects of the precursor layer will provide insights into the carrier scattering mechanisms and hence into the performance of graphene-based devices. Furthermore, we will identify reconstructions of the precursor layer that are particularly suitable as templates for the assembly of regular arrays of nanostructures such as fullerenes, metallic clusters, and functional molecules. Aspects of this work will be presented in recently developed courses at Colorado School of Mines and Brown University. The investigators will be actively involved in career advising and student mentorship, and will use the results of this research to enhance the experiences of K-12 mathematics teachers and high-school students under the outreach program of the Materials Research Science and Engineering Center at Brown.