11-02/03 :: February / March 2011

nanotimes News in Brief

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Nanoribbons // New Technique Produces Structures with Metallic Properties

has produced structures just 15 to 40nm wide that conduct current with almost no resistance. The new fabrication technique allows production of epitaxi- al graphene structures with smooth edges. Earlier fabrication techniques that used electron beams to cut graphene sheets produced nanoribbon structures with rough edges that scattered electrons, causing in- terference. The resulting nanoribbons had properties more like insulators than conductors.

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“In our templated growth approach, we have essen- tially eliminated the edges that take away from the desirable properties of graphene,” Walt de Heer ex- plained. “The edges of the epitaxial graphene merge into the silicon carbide, producing properties that are really quite interesting.”

The “templated growth” technique begins with etching patterns into the silicon carbide surfaces on which epitaxial graphene is grown. The patterns serve as templates directing the growth of graphene structures, allowing the formation of nanoribbons and other structures of specific widths and shapes without the use of cutting techniques that produce the rough edges. In creating these graphene nano- structures, de Heer and his research team first use conventional microelectronics techniques to etch tiny “steps” – or contours – into a silicon carbide

new “templated growth” technique for fabricating nanoribbons of epitaxial graphene

A team of Georgia Tech researchers led by Professor Walt de Heer has pioneered techniques for fabricating epitaxial graphene nanoribbons using a templated growth tech- nique. The equipment shown behind de Heer is used to characterize graphene properties. © Mali Azima

wafer whose surface has been made extremely flat. They then heat the contoured wafer to approximate- ly 1,500 degrees Celsius, which initiates melting that polishes any rough edges left by the etching process.

De Heer discussed recent results of this graphene growth process at the American Physical Society’s March 2011 Meeting in Dallas, USA.

De Heer’s research team hopes to demonstrate a rudimentary switch operating on the quantum interference principle within a year.

http://www.physics.gatech.edu/