A physical chemist is excited by the electronic potential of a new arrangement of carbon sheets.

Graphene is high on the list of hot new materials. The one-atom-thick sheets of carbon have exceptional mechanical, thermal and optical properties, which researchers are impatient to exploit. Graphene is also interesting for its high electrical conductivity; it is possible that graphene could one day supplant or complement silicon in electronic devices.

That possibility was recently given a boost by Edward Conrad of the Georgia Institute of Technology in Atlanta and his colleagues, who grew layers of graphene on a special crystal face of silicon carbide (M. Sprinkle et al. Phys. Rev. Lett. 103, 226803; 2009).

Normally, graphene layers occur in stacks in an arrangement we know as graphite — an important ore used worldwide in everything from pencils to automobile brake linings. The graphene layers in graphite repeat with a regular 'AB' pattern. Overall, graphite has poorer electrical conductivity than graphene.

The graphene film grown by the Georgia Tech team is quite different. It consists of stacked layers with a peculiar rotational order, and could mark a brand new phase of graphite. More importantly, the way in which the layers are stacked relative to each other preserves graphene's high electrical conductivity — in other words, the ensemble does not behave like graphite.

My research group had already layered graphene sheets into a similar 'non-graphite'. But we had to grow layers of graphene one at a time and stack them sequentially. The Georgia Tech group shows that a similar structure can be obtained all at once by growing a single film. The material could have important implications for nanoelectronics, and might find other uses — for instance, as films in which transparency and conductivity can be tuned by adjusting the number of graphene layers.

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