Article abstract

Nature Materials 8, 235 - 242 (2009)
Published online: 15 February 2009 | doi:10.1038/nmat2378

Subject Categories: Nanoscale materials | Characterisation and analytical techniques

The influence of edge structure on the electronic properties of graphene quantum dots and nanoribbons

Kyle A. Ritter1,2 & Joseph W. Lyding1,3

Graphene shows promise as a future material for nanoelectronics owing to its compatibility with industry-standard lithographic processing, electron mobilities up to 150 times greater than Si and a thermal conductivity twice that of diamond. The electronic structure of graphene nanoribbons (GNRs) and quantum dots (GQDs) has been predicted to depend sensitively on the crystallographic orientation of their edges; however, the influence of edge structure has not been verified experimentally. Here, we use tunnelling spectroscopy to show that the electronic structure of GNRs and GQDs with 2–20 nm lateral dimensions varies on the basis of the graphene edge lattice symmetry. Predominantly zigzag-edge GQDs with 7–8 nm average dimensions are metallic owing to the presence of zigzag edge states. GNRs with a higher fraction of zigzag edges exhibit a smaller energy gap than a predominantly armchair-edge ribbon of similar width, and the magnitudes of the measured GNR energy gaps agree with recent theoretical calculations.

  1. Beckman Institute for Advanced Science and Technology, University of Illinois, 405 North Mathews Avenue, Urbana, Illinois 61801-2325, USA
  2. Department of Materials Science and Engineering, University of Illinois, 1304 West Green Street, Urbana, Illinois 61801-2920, USA
  3. Department of Electrical and Computer Engineering, University of Illinois, 1406 West Green Street, Urbana, Illinois 61801-2918, USA

Correspondence to: Kyle A. Ritter1,2 e-mail:


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