Current Trends in Scanning Tunneling Microscopy at Argonne
Low-dimensional materials functioning at the nanoscale are a critical component for a variety of current and future technologies. From the optimization of light harvesting solar technologies to large-scale catalytic processes, key physical phenomena are occurring at the nanometer and atomic length-scales and predominately at interfaces. For instance, graphene is a nearly ideal two-dimensional conductor that is comprised of a single sheet of hexagonally packed carbon atoms. In order fully realize the potential of graphene for novel electronic applications, large-scale synthesis of high quality graphene and the ability to control the electronic properties of this material on a nanometer length scale are key challenges. At the same time, the 2-dimensional interface of complex oxide heterostructures play a dominant role in the resulting physical properties of these strongly correlated materials. These interfaces present a difficult challenge for direct characterization. This talk will highlight how scanning probe microscopy presents a series of powerful experimental tools that can overcome several challenges and allow for the direct characterization of several advanced materials.
This talk will cover our novel cross-sectional scanning tunneling microscopy techniques for directly probing complex oxide interfaces at the atomic scale for the first time. In addition, we have demonstrated the reversible and local modification of graphene’s electronic properties by hydrogen passivation and subsequent electron-stimulated hydrogen desorption with a scanning tunneling microscope tip. I will also present our growth studies of graphene on single crystal Cu(111) surfaces and Cu foil by variable temperature scanning tunneling microscopy and spectroscopy.1-4 These studies include the atomic configuration between copper and graphene, as well as the atomic-scale electronic structure of the graphene on the copper surface. Our results provide valuable information for understanding the growth mechanism and the electronic quality of graphene on copper. Finally, our most recent studies of chiral amino acids and molecular technologies will be covered.
1. L. Gao, J. R. Guest, and N. P. Guisinger: Epitaxial Graphene on Cu(111), Nano Lett. 10, 3512 (2010).
2. Q. Yu, et al.: Control and characterization of individual grains and grain boundaries in graphene grown by chemical vapour deposition, accepted Nature Materials, 10, 443 (2011).
3. J. Cho, et al.: Atomic-scale investigation of graphene grown on Cu foil and the effects of thermal annealing, under review ACS Nano, 5, 3607 (2011).
4. J. Cho, et al.: Structural and Electronic Decoupling of C60 from Epitaxial Graphene on SiC. Nano Lett. 10, 3512 (201