"Surface Potentials and Layer Charge Distributions in Few-Layer Graphene Films"
Douglas R. Strachan
University of Pennsylvania
Graphene-derived nanomaterials are emerging as ideal candidates for postsilicon
electronics. Elucidating the electronic interaction between an insulating substrate and
few-layer graphene (FLG) films is crucial for device applications. Electrostatic force
microscopy (EFM) reveals that the FLG surface potential increases with film thickness,
approaching a “bulk” value for samples with five or more graphene layers. This is in
quantitative agreement with the analytic predictions of a nonlinear Thomas-Fermi theory
of the interlayer screening by graphene's relativistic low energy charge carriers. Our
measurements are also able to resolve previously unseen electronic perturbations
extended along crystallographic directions of stressed samples, likely resulting from
long-range atomic defects. These results have important implications for graphene
nanoelectronics and provide a framework by which the electrostatics of this layered
system can be investigated.
* Work done in collaboration with Sujit S. Datta, Eugene J. Mele, and A. T. Charlie
Johnson in the Department of Physics and Astronomy at the University of Pennsylvania.
** This work was supported by the Nano/Bio Interface Center through the National
Science Foundation NSEC DMR-0425780 and the JSTO DTRA, the Army Research
Office Grant #W911NF-06-1-0462, and the Intelligence Community Postdoctoral
Fellowship Program.

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