Transistor is 1 Atom Thick

Graphene, a single-atom-thick sheet of graphite that combines aspects of semiconductors and metals, has been carved into tiny electronic circuits containing individual transistors not much bigger than a molecule.

Kostya Novoselov, PhD, and professor Andre Geim from The School of Physics and Astronomy at The University of Manchester led the research into using graphene to make the one-atom-thick and 10-atoms-wide transistors, and said the smaller they make their transistors the better they perform.

Leonid Ponomarenko, a researcher working in the Mesoscopic Physics Group at the University of Manchester with Andre Geim and Kostya Novoselov, holds a chip containing a graphene transistor. (Image courtesy University of Manchester)

In recent decades, manufacturers have crammed more and more components onto integrated circuits (ICs). As a result, the number of transistors and the power of ICs have roughly doubled every two years. But the speed of cramming is now noticeably decreasing as the semiconductor industry is challenged to continue to make ICs smaller and smaller while also bettering their performance.

At the heart of the problem is the poor stability of materials if shaped in elements smaller than 10 nanometers (a human hair is about 100,000-nm wide). At this spatial scale, all semiconductors -- including silicon -- oxidize, decompose and uncontrollably migrate along surfaces like water droplets on a hot plate.

Four years ago, Geim and his colleagues discovered graphene, the first known one-atom-thick material which can be viewed as a plane of atoms pulled out from graphite. Graphene has rapidly become the hottest topic in physics and materials science, and recently its ability to conduct electricity was found to be higher than any other known material at room temperature, making it a promising replacement for conventional semiconductor materials such as silicon in applications ranging from high-speed computer chips to biochemical sensors (See also: Graphene In, Silicon Out?).

Now the Manchester team has shown that it is possible to carve out nanometer-scale transistors from a single graphene crystal. Unlike all other known materials, graphene remains highly stable and conductive even when it is cut into devices 1-nm wide. (See also: Graphene Discovery Leads to Top Physics Prize).

Graphene transistors start showing advantages and good performance at sizes below 10 nanometers -- the miniaturization limit at which the silicon technology is predicted to fail.

"Previously, researchers tried to use large molecules as individual transistors to create a new kind of electronic circuits. It is like a bit of chemistry added to computer engineering," said Novoselov. "Now one can think of designer molecules acting as transistors connected into designer computer architecture on the basis of the same material (graphene), and use the same fabrication approach that is currently used by semiconductor industry."

"It is too early to promise graphene supercomputers," said Geim. "In our work, we relied on chance when making such small transistors. Unfortunately, no existing technology allows the cutting of materials with true nanometer precision. But this is exactly the same challenge that all post-silicon electronics has to face. At least we now have a material that can meet such a challenge."

The researchers reported their findings in the paper, "Chaotic Dirac Billiard in Graphene Quantum Dots," in the April 17 issue of the journal Science.

For more information, visit: www.manchester.ac.uk