Applied Physics

Clean Up on Graphene

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Science  15 Jun 2007:
Vol. 316, Issue 5831, pp. 1543
DOI: 10.1126/science.316.5831.1543b

Graphene, which comprises exfoliated sheets of graphite that are often supported on a dielectric substrate, can display unusual electronic properties that arise through two-dimensional confinement, and in device configurations, biasing of the dielectric can be used to control its conductivity. Although these materials are often assumed to be nearly ideal, in practice the dielectric layer could have trapped charges, and materials used in processing could remain on the graphene. Ishigami et al. present atomic-resolution scanning tunneling microscopy studies of graphene devices supported on silica. The as-processed graphene surfaces are covered with photoresist and could not be atomically imaged, even after solvent cleaning. Exposure to an argon-hydrogen atmosphere at 400°C removes the photoresist layer and reveals the influence of the dielectric layer: In addition to the expected hexagonal patterns, a triangular lattice is observed, either from film curvature or the effect of trapped charges. The graphene layer exhibits corrugations that follow the underlying substrate's roughness. — PDS

Nano Lett. 7, 10.1021/nl070613a (2007).

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