Growth and Interface Physics of Epitaxial Graphene

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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.