News FocusMATERIALS RESEARCH SOCIETY FALL MEETING

Graphene Recipe Yields Carbon Cornucopia

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Science  19 Dec 2008:
Vol. 322, Issue 5909, pp. 1785
DOI: 10.1126/science.322.5909.1785

MATERIALS RESEARCH SOCIETY FALL MEETING, 1-5 DECEMBER, BOSTON

The hottest material in physics these days is graphene, sheets of carbon just a single atom thick. Graphene is flexible yet harder than diamond. It conducts electricity faster at room temperature than anything else. And it's nearly transparent, a handy property for devices such as solar cells and displays that need to let light through. The only trouble is that people have been able to make only small flakes of the stuff—until now.

At the meeting, Alfonso Reina Cecco, a graduate student in chemist Jing Kong's lab at the Massachusetts Institute of Technology (MIT) in Cambridge, reported that he and several colleagues have come up with a cheap, easy way to grow high-quality graphene films and then transfer them wherever they want. “That's a big deal,” says Andre Geim, a physicist at the University of Manchester, U.K., who first reported making graphene (Science, 22 October 2004, p. 666). “It promises wafers [of graphene]. That changes everything.” It opens the door both to better ways of exploring the new physics of atomically thin materials and to potential applications.

To create the first graphene sheets in 2004, Geim peeled single layers of graphene off chunks of graphite with clear tape. But that low-tech approach would be hard to scale up for industrial use. Researchers at the Georgia Institute of Technology in Atlanta came closer in 2004 by growing graphene films atop a substrate made of silicon carbide. But silicon carbide is expensive and must be processed in an ultrahigh vacuum, which also raises the cost.

Film star.

Graphene is prized for its electrical properties. Now, researchers can make sheets of the atomically thin material and pattern them for devices.

CREDIT: A. REINA ET AL., NANO LETTERS (ADVANCE ONLINE PUBLICATION) © 2008 AMERICAN CHEMICAL SOCIETY

At the meeting, Cecco reported that the MIT team had done away with the silicon carbide. Instead, they deposited a film of nickel atop a standard silicon wafer. They then used a conventional film-growing technique known as chemical vapor deposition to add graphene in either a single sheet or a stack of a few sheets.

To transfer their graphene sheets to another surface, the MIT team coated it with a polymer known as PMMA, then etched away the silicon and the nickel after that, leaving only the graphene on the polymer film. Finally, they covered the newly reexposed graphene surface with glass and then dissolved away the PMMA. By initially patterning the nickel layer, Cecco and his MIT colleagues also showed that they could make graphene films in arbitrary patterns, such as those typically used to make electronic devices. The same day Cecco gave his talk, a paper on the topic was published online in Nano Letters.

This ability to pattern and place graphene wherever it's needed, Geim says, will only increase the amount of research done with the material, ensuring that it will stay among the hottest materials in physics.

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