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Super-thin Material //

With Support, Graphene Still a Superior Thermal Conductor

lege, and France‘s Commission for Atomic Energy

report the super-thin sheet of carbon atoms – taken from the three-dimensional material graphite – can transfer heat more than twice as efficiently as copper thin films and more than 50 times better than thin films of silicon.

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The research advances the understanding of gra- phene as a promising candidate to draw heat away from “hot spots” that form in the tight knit spaces of devices built at the micro and nano scales. From a theoretical standpoint, the team also developed a new view of how heat flows in graphene.

When suspended, graphene has extremely high thermal conductivity of 3,000 to 5,000 watts per meter per Kelvin. But for practical applications, the chicken-wire like graphene lattice would be attached to a substrate. The team found supported graphene still has thermal conductivity as high as 600 watts per meter per Kelvin near room temperature. That far exceeds the thermal conductivities of copper, appro- ximately 250 watts, and silicon, only 10 watts, thin films currently used in electronic devices.

The loss in heat transfer is the result of graphene‘s in- teraction with the substrate, which interferes with the vibrational waves of graphene atoms as they bump

team of engineers and theoretical physicists from

the University of Texas at Austin, Boston Col-

against the adjacent substrate, according to co-author David Broido, a Boston College Professor of Physics.

The conclusion was drawn with the help of earlier theoretical models about heat transfer within suspen- ded graphene, Broido said. Working with former BC graduate student Lucas Lindsay, now an instructor at Christopher Newport University, and Natalio Mingo of France‘s Commission for Atomic Energy, Broido re-examined the theoretical model devised to ex- plain the performance of suspended graphene.

“As theorists, we‘re much more detached from the device or the engineering side. We‘re more focused on the fundamentals that explain how energy flows through a sheet graphene. We took our existing model for suspended graphene and expanded the theoretical model to describe this interaction that takes place between graphene and the substrate and the influence on the movement of heat through the material and, ultimately, it‘s thermal conductivity.”

Jae Hun Seol, Insun Jo, Arden L. Moore, Lucas Lindsay, Zachary H. Aitken, Michael T. Pettes, Xuesong Li, Zhen Yao, Rui Huang, David Broido, Natalio Mingo, Rodney S. Ruoff, and Li Shi: Two-Dimensional Phonon Transport in Supported Graphene, In: Science, Vol. 328(2010), Issue 5975, April 09, 2010, Pages 213-216, DOI:10.1126/sci- ence.1184014:

http://dx.doi.org/10.1126/science.1184014

10-04 :: April 2010