Teague, M. L. and Lai, A. P. and Velasco, J. and Hughes, C. R. and Beyer, A. D. and Bockrath, M. W. and Lau, C. N. and Yeh, N.-C. (2009) Evidence for Strain-Induced Local Conductance Modulations in Single-Layer Graphene on SiO2. Nano Letters, 9 (7). pp. 2542-2546. ISSN 1530-6984 http://resolver.caltech.edu/CaltechAUTHORS:20090828-143159875
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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 SiO_2 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.
|Additional Information:||Copyright © 2009 American Chemical Society. Received February 21, 2009; Revised Manuscript Received June 8, 2009. Publication Date (Web): June 17, 2009. The work at Caltech was jointly supported by NSF and NRI under the Center of Science and Engineering of Materials. C.N.L. and J.V. acknowledge the support by NSF CAREER DMR/0748910, UC Lab Fees 09-LR-06-117702-BASD, and ONR N00014-09-1-0724. We thank Dr. A. V. Balatsky for useful discussions.|
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|Deposited By:||George Porter|
|Deposited On:||11 Sep 2009 16:15|
|Last Modified:||26 Dec 2012 11:16|
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