Locating and Imaging Single-Layer Graphene

Chun Ning (Jeanie) Lau, Assistant Professor Department of Physics Dr. Lau received her BA from University of Chicago and PhD in physics from Harvard University. Her work at Harvard investigating the fundamental limit to superconductivity in nanowires was reported in popular international magazines such as The Economist and Profil. Her current research effort is to explore novel phenomena of nanoscale systems such as nanowires, carbon nanotubes, graphene and organic molecules. Before joining UC Riverside in 2004, Dr. Lau was a research associate at the Advanced Studies Group at the Hewlett – Packard Laboratories in Palo Alto, California. Dr. Lau commented,“Sitara has worked in my group since the summer of 2005. Her patience and diligence at exfoliating and inspecting graphite pieces has been critical to the success of our electrical measurement of single layer graphene. She is currently the second-author of a submitted manuscript.” F A C U L T Y M E N T O R Graphene, a two-dimensional counterpart of graphite, is made up of sp2 carbon bonded atoms arranged in a honeycomb lattice. The separation of graphite into a one-atom thick sheet is accomplished by rubbing natural graphite on a silicon substrate. Once this action is taken, the monolayers can be discerned using the combination of an optical microscope for color interference and an atomic force microscope for analysis of topological features. Our project explores the interplay between superconductivity and the unique band structure of graphene. Single-layer graphene is known to exhibit unusual electronic properties that are characteristic of Dirac fermions. Two terminal transport measurements of the single-layer graphene suggest that the maximum resistance is approximately 12.5 kΩ, which describes the anomalous quantum Hall effect. It should be noted that the electrostatic force microscopy scanning presented here is preliminary, intended only to illustrate the coexistence of regions with metallic and insulator behaviors in single-layer graphene. This property contradicts classical studies, which predict equipotential distribution on the surface due to graphene’s periodic crystal-lattice structure. LOCATING AND IMAGING SINGLE-LAYER GRAPHENE