Berlin 2012 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 66: Nanostructures at surfaces III
O 66.1: Vortrag
Donnerstag, 29. März 2012, 10:30–10:45, MA 042
Conductance measurements of single graphene nanoribbons with scanning tunnelling microscopy — •Matthias Koch1, Francisco Ample2, Christian Joachim2,3, and Leonhard Grill1 — 1Dept. of Physical Chemistry, Fritz-Haber-Institute of the Max-Planck-Society, Berlin, Germany — 2Institute of Materials Research and Engineering (IMRE), Singapore — 3Nanosciences Group, CEMES-CNRS, Toulouse, France
Graphene nanoribbons (GNR) are promising candidates for molecular wires in future nanotechnology. Their planar atomic structure leads to electronic properties that strongly depend on their edge-structure and width. We have assembled such GNRs in a bottom-up approach directly on a metal surface and characterized them by low temperature scanning tunneling microscopy (LT-STM). Such a process leads to atomically defined edges, which are required for charge transport studies as structural defects have been predicted to modify the electronic structure and to reduce the conductance. After their characterization by STM, we have performed conductance measurements of single GNRs by pulling them off the surface with the STM tip. In this way, single molecules are contacted to two electrodes in a controlled way and can at the same be characterized before and after such a procedure at the atomic level. Importantly, the electrode-electrode distance is varied during the measurements, thus allowing length-dependent conductance measurements, which are necessary for a fundamental understanding of charge transport. We find that the conductance exponentially decreases with the molecular length in the junction.