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nanotimes News in Brief

Graphene // Seeing an Atomic Thickness

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cientists from National Physical Laboratory, U.K., in collaboration with Linköping University, Swe-

den, have shown that regions of graphene of diffe- rent thickness can be easily identified in ambient conditions using Electrostatic Force Microscopy (EFM).

The exciting properties of graphene are usually only applicable to the material that consists of one or two layers of the graphene sheets. Whilst synthesis of any number of layers is possible, the thicker layers have properties closer to the more common bulk graphite.

For device applications one- and two-layer graphene needs to be precisely identified apart from the sub- strate and regions of thicker graphene. Exfoliated graphene sheets up to ~100 μm in size can be routi- nely identified by optical microscopy.

However, the situation is much more complicated in the case of the epitaxial graphene grown on silicon carbide wafers with a diameter up to 5 inches where the straightforward identification of the graphene thickness is difficult using standard techniques. This research shows that EFM, which is one of the most widely accessible and simplest implementations of scanning probe microscopy, can clearly identify diffe- rent graphene thicknesses. The technique can also be used in ambient environments applicable to industri- al requirements.

The left hand image is the topography; the middle the topography error image; and right the electrostatic force microscopy image where the tip bias has been switched half way through the image. © NPL, U.K.

11-06/07 :: June/July 2011

Tim Burnett, Rositza Yakimova, and Olga Kazakova: Map- ping of Local Electrical Properties in Epitaxial Graphene Using Electrostatic Force Microscopy, In: NANO Letters, Vol. 11(2011), No. 6, June 8, 2011, Pages 2324-2328, DOI:10.1021/nl200581g: http://dx.doi.org/10.1021/nl200581g

Functional Materials research: http://www.npl.co.uk/category/347

Quantum Phenomena: http://www.npl.co.uk/quantum-phenomena/