Voltage-dependent conductance of a single graphene nanoribbon

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Abstract

Graphene nanoribbons could potentially be used to create molecular wires with tailored conductance properties. However, understanding charge transport through a single molecule requires length-dependent conductance measurements and a systematic variation of the electrode potentials relative to the electronic states of the molecule1,2. Here, we show that the conductance properties of a single molecule can be correlated with its electronic states. Using a scanning tunnelling microscope, the electronic structure of a long and narrow graphene nanoribbon, which is adsorbed on a Au(111) surface, is spatially mapped and its conductance then measured by lifting the molecule off the surface with the tip of the microscope. The tunnelling decay length is measured over a wide range of bias voltages, from the localized Tamm states over the gap up to the delocalized occupied and unoccupied electronic states of the nanoribbon. We also show how the conductance depends on the precise atomic structure and bending of the molecule in the junction, illustrating the importance of the edge states and a planar geometry.

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Figure 1: Electronic structure of single graphene nanoribbons.
Figure 2: Single-molecule conductance measurements.
Figure 3: Charge transport for different electron energies and molecular structures.
Figure 4: Calculated conductance for different cases.

Change history

  • 19 October 2012

    In the version of this Letter originally published online, in the caption for Fig. 1g, the value of the bias voltage was incorrect and should have read −0.55 V. This error has been corrected in all versions of the Letter.

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Acknowledgements

The authors acknowledge financial support from European Projects ARTIST and AtMol and the German Science Foundation DFG (through SFB 658). We also acknowledge the A*STAR Computational Resource Centre (A*CRC) for the computational resources and support.

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M.K. performed the experiments. M.K. and L.G. analysed the data. F.A. and C.J. carried out the theoretical calculations. L.G. conceived the experiments. L.G. and C.J. wrote the paper. All authors discussed the results and commented on the manuscript.

Corresponding author

Correspondence to Leonhard Grill.

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The authors declare no competing financial interests.

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Koch, M., Ample, F., Joachim, C. et al. Voltage-dependent conductance of a single graphene nanoribbon. Nature Nanotech 7, 713–717 (2012). https://doi.org/10.1038/nnano.2012.169

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