### Session K2: Carbon Nanostructures I

Chair: Brian LeRoy, University of Arizona
Room: UA Student Union Ventana

 Saturday, October 22, 2011 8:30AM - 8:42AM K2.00001: Low-Z, Chemically Resistant, Microfabricated Carbon Composite Transmission Electron Microscope Grids Kyle Zufelt , Richard Vanfleet , Robert Davis An issue that often impacts x-ray and electron analysis of electron microscopy samples is the presence of high-Z atoms in the chosen substrate. In many cases, it is also desirable that the chosen substrate be resistant to chemicals and various processing methods. We present an improved transmission electron microscope (TEM) grid made by carbon-infiltrated carbon nanotube templated microfabrication (CNT-M). We present a method for controlling the delamination of carbon-infiltrated carbon structures as well as a batch process for coating CNT-M structures in suspended thin films. Several membranes were deposited on the grids, including Formvar, amorphous carbon, silicon dioxide, and alumina. These grids provide a significant advantage in analytical TEM applications due to the absence of high-Z atoms and the improved chemical resistivity which allows for a wider range of sample preparation and processing techniques. The refinement of the CNT-M process may have applications in future research on MEMS and other CNT-M devices. Saturday, October 22, 2011 8:42AM - 8:54AM K2.00002: Mechanical and Electrical Properties of Carbon Nanotube Templated Metal Microstructures Richard Hansen , David McKenna , Brian Jensen , Richard Vanfleet , Robert Davis , David Allred Our group has used vertically aligned carbon nanotubes as a patterned, three-dimensional microfabrication scaffold to create CNT composite materials through chemical vapor infiltration. This method, termed carbon nanotube templated microfabrication (CNT-M), is a novel approach for creating precise high-aspect-ratio microstructures. In the past, dielectrics (SiO$_{2}$ and SiN$_{x})$ and semiconductors (Si and a-C) were the materials deposited on the CNT framework. Production and characterization of metallic microstructures is in its infancy. This study presents electrical, mechanical and structural properties of \textit{metallic} microstructures made using tungsten and molybdenum carbonyl precursors through the CNT-M process. Saturday, October 22, 2011 8:54AM - 9:06AM K2.00003: Edge effects in chemical vapor deposition grown graphene Matthew Yankowitz The study of graphene has been extremely popular recently due to its promising properties as a replacement for silicon in next-generation electronics. While most of its basic properties are now well understood, there are still many interesting electronic edge effects which have yet to be sufficiently probed experimentally. These edge effects become especially important for nano-scale graphene devices, where electronic edge states persist throughout a considerable proportion of the device area. I will present methods for fabricating chemical vapor deposition (CVD) grown graphene on boron nitride devices. These devices are clean and atomically flat allowing the electronic edge effects to be probed with scanning tunneling spectroscopy. I will also present evidence that CVD grown graphene edges are not atomically precise enough to support electronic edge states or other interesting edge effects such as short-wavelength Friedel oscillations. Saturday, October 22, 2011 9:06AM - 9:18AM K2.00004: The number of transmission channels through a buckyball Jarred Hudson , Michael Stefferson , Charles Stafford Transmission through nanoscale junctions consisting of a single Buckminsterfullerene molecule between two Pt electrodes is investigated in the nonequilibrium Green's function approach within Hueckel theory. Junction ensembles for hexagon-hexagon, hexagon-pentagon, and pentagon-pentagon contacts to the two Pt electrodes are analyzed. We find that the transmission eigenvalue distribution is limited by the degeneracy of the molecular resonance closest to the Pt Fermi level. However, interference effects strongly suppress the contributions of some of the degenerate channels. Saturday, October 22, 2011 9:18AM - 9:30AM K2.00005: Scanning tunneling spectroscopy of graphene on boron nitride Jiamin Xue , Javier Sanchez-Yamagishi , Danny Bulmash , Philippe Jacquod , Aparna Deshpande , K. Watanabe , T. Taniguchi , Pablo Jarillo-Herrero , Brian LeRoy We have performed low-temperature scanning tunneling microscopy and spectroscopy measurements of graphene on hexagonal boron nitride (hBN). We found that the topographic variations are reduced by one order of magnitude as compared to graphene on SiO2. We also performed scanning tunneling spectroscopy measurements to study the spatial variation of the Dirac point. We found that the electrochemical potential homogeneity is improved by one order of magnitude as compared to graphene on SiO2. These results provide a microscopic explanation for recent transport experiments of graphene on hBN showing improved mobility.