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arXiv · 0903.2327

Evidence for Strain-Induced Local Conductance Modulations in Single-Layer Graphene on SiO2

M. L. Teague·A. P. Lai·J. Velasco·C. R. Hughes·A. D. Beyer·M. W. Bockrath·C. N. Lau·N. -C. Yeh
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Abstract

Graphene has emerged as an electronic material that is promising for device applications and for studying two-dimensional electron gases with relativistic dispersion near two Dirac points. Nonetheless, deviations from Dirac-like spectroscopy have been widely reported with varying interpretations. Here we show evidence for strain-induced spatial modulations in the local conductance of single-layer graphene on SiO2 substrates from scanning tunneling microscopic (STM) studies. We find that strained graphene exhibits parabolic, U-shaped conductance vs. bias voltage spectra rather than the V-shaped spectra expected for Dirac fermions, whereas V-shaped spectra are recovered in regions of relaxed graphene. Strain maps derived from the STM studies further reveal direct correlation with the local tunneling conductance. These results are attributed to a strain-induced frequency increase in the out-of-plane phonon mode that mediates the low-energy inelastic charge tunneling into graphene.

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M. L. Teague, A. P. Lai, J. Velasco, C. R. Hughes, A. D. Beyer, M. W. Bockrath, C. N. Lau, N. -C. Yeh. 2009-03-13. Evidence for Strain-Induced Local Conductance Modulations in Single-Layer Graphene on SiO2. https://doi.org/10.1021/nl9005657

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