12-01 :: January 2012
nanotimes News in Brief Graphene //
Graphene Moves into Computer Chips © Based on Material by The University of Manchester, UK
phene research. Individual transistors with very high frequencies (up to 300 GHz) have already been de- monstrated by several groups worldwide, but those transistors cannot be packed densely in a computer chip because they leak too much current, even in the most insulating state of graphene. This electric cur- rent would cause chips to melt within a fraction of a second. This problem has been around since 2004.
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The University of Manchester scientists now suggest using graphene not laterally (in plane) – as all the previous studies did – but in the vertical direction. They used graphene as an electrode from which electrons tunnelled through a dielectric into another metal. This is called a tunnelling diode. Then they exploited a truly unique feature of graphene – that an external voltage can strongly change the energy of tunnelling electrons. As a result they got a new type of a device – vertical field-effect tunnelling transistor in which graphene is a critical ingredient.
Dr Leonid Ponomarenko, who spearheaded the experimental effort, said: “We have proved a con- ceptually new approach to graphene electronics. Our transistors already work pretty well. I believe they can be improved much further, scaled down to nanometre sizes and work at sub-THz frequencies.”
Tunnelling transistor based on vertical graphene hete- rostructures. Tunnelling current between two graphene layers can be controlled by gating. © University of Manchester, UK
research team at University of Manchester (U.K.) has literally opened a third dimension in gra-
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“The demonstrated transistor is important but the concept of atomic layer assembly is probably even more important,” explains Professor Geim.
L. Britnel, R. Gorbache, R. Jalil, B. Bell, F. Schedin, A. Mishchenko, T. Georgiou, M. Katsnelson, L. Eaves, S. Mo- rozov, N. Peres, J. Leist, A. Geim, K. Novoselov, and L. Ponomarenko: Field-effect tunneling transistor based on vertical graphene heterostructures, In: Science Express, February 02, 2012, DOI:10.1126/science.1218461:
http://dx.doi.org/10.1126/science.1218461
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