Graphene could someday replace silicon as a semiconductor material and make our chips smaller and faster, except for one tiny detail: it’s been rather hard to mess with its electronic properties. Until now.
“We have experimentally realized and theoretically investigated, for the first time, perfect atomic wires in graphene,” Ivan Oleynik, one of the two University of South Florida professors behind the discovery, told Wired.com. Atomic wires are short chains of atoms that conduct electricity and so far, they have been hard to achieve in graphene.
The researchers have found a way to introduce one-dimensional defects that are stable and in the center of a graphene sheet. The breakthroughs could lead to more widespread applications for graphene including the ability to ultimately create faster chips and smaller gadgets.
Oleynik and his fellow researcher Matthias Batzill published a paper in Nanotechnology Journal last week, announcing their solution for controlling graphene’s electronic properties.
To keep up with Moore’s law–which says that the number of transistors that can be affordably built into a processor doubles roughly every two years–chip makers have to keep shrinking silicon-based chips. Intel’s latest processors, for example, use a 32-nanometer technology to create chips. But many researchers believe it will get increasingly difficult to manufacture smaller transistors, especially in the 10-nanometers range.
In the last few years, graphene, a form of carbon derived from graphite oxide, has emerged as a promising alternative to silicon. It’s one atom thick and has phenomenal electron mobility – roughly 100 times greater than silicon.
Few months ago, IBM said its graphene-based transistors could reach speeds of 100 Ghz. Two years ago, British scientists unveiled the world’s smallest transistor – three times smaller than the silicon-based ones–that was made of graphene.
“From the point of view of physics, graphene is a goldmine,” Kostya Novoselov, a researcher at the University of Manchester who worked on that project, told Wired.com in 2008.
But for graphene to be useful in electronic applications like integrated circuits, small defects, also known as atomic-scale imperfections, have to be introduced in the material. “All previous attempts used so-called graphene nanoribbons,” says Oleynik, “and that could lead to chemical instabilities, since there are dangling bonds on the edges. ”
Defects on nanoribbons – tiny strips of graphene – have often been inconsistent and hard to create since the edges are rough and chemically unstable.
Instead, their solution, say the researchers, is a one-dimensional defect that creates octagonal and pentagonal rings. It acts like a metallic wire and can conduct electric current.
“Our defect is embedded into the graphene, as opposed to being on the edges, which allows for more flexibility,” says Batzill.
Graphene has become a real alternative for building atomic-scale, all-carbon based electronics, say the researchers.
(Photo: Y. Lin, USF)
