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February 28, 2007

Smallest transistor made from graphene

Professor Andre Geim and Dr Kostya Novoselov from The School of Physics and Astronomy at The University of Manchester, reveal details of transistors that are only one atom thick and less than 50 atoms wide, in the March issue of Nature Materials.

Professor Geim and colleagues have shown for the first time that graphene remains highly stable and conductive even when it is cut into strips of only a few nanometres wide.

All other known materials – including silicon – oxidise, decompose and become unstable at sizes tens times larger.

The research team suggests that future electronic circuits can be carved out of a single graphene sheet. Such circuits would include the central element or 'quantum dot', semitransparent barriers to control movements of individual electrons, interconnects and logic gates – all made entirely of graphene.

Geim's team have proved this idea by making a number of single-electron-transistor devices that work under ambient conditions and show a high-quality transistor action.

"At the present time no technology can cut individual elements with nanometre precision. We have to rely on chance by narrowing our ribbons to a few nanometres in width," says Dr Leonid Ponomarenko, who is leading this research at The University of Manchester. "Some of them were too wide and did not work properly whereas others were over-cut and broken."

But Dr Ponomarenko is optimistic that this proof-of-concept technique can be scaled up. "The next logical step is true nanometre-sized circuits and this is where graphene can come into play because it remains stable – unlike silicon or other materials – even at these dimensions."

Professor Geim does not expect that graphene-based circuits will come of age before 2025. Until then, silicon technology should remain dominant.

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