Friday, April 18, 2008

Scientists Build World's Smallest Transistor, Gordon Moore Sighs With Relief

British researchers have unveiled the world's smallest transistor, which measures one atom thick and ten atoms across.

The newly announced transistor is more than three times smaller than the 32 nanometer transistors at the cutting edge of silicon-based electronics.

"It's molecular electronics with the standard top-down approach which can be used in any semiconductor factory," said Kostya Novoselov, a researcher at the University of Manchester and a co-author of a new paper on the transistor in the journal Science.
Transistors form the logic gates that underpin computing. Finding new ways to make them smaller is key to the continuation of Moore's Law, which holds that the number of transistors on a chip will double every two years. That doubling translates into performance gains for computers. While expected improvements to processes and materials, namely silicon, seem likely to keep the law going for the next ten years, even Gordon Moore questions technology's ability to keep pace after that.

This new transistor may extend Moore's Law for a while longer.

The transistor is made out of graphene, a new material exactly one-atom thick that was discovered by Novoselov' s research team in 2004.

Made of intricately linked carbon atoms, graphene has the ability to retain several important properties when only one atom thick -- most importantly conductivity.
When current silicon transistor technology goes below 10 nanometers in size, it's predicted it will run into the laws of physics and will no longer be able to create reliable transistors.

Graphene, on the other hand, is already seeing working transistors in the sub-10 nanometer range. The researchers say their latest, unpublished work has used graphene to make transistors a single nanometer across. "

From the point of view of physics, graphene is a goldmine," said Novoselov. "You can study it for ages."

The researchers created the graphene transistors using standard semiconductor fabrication technology. They begin with a small sheet of graphene and carve channels into the material using electron beam lithography. What remains is a quantum dot with a tiny circular cage at the center known as the central island. Voltage can change the conductivity of these quantum dots, allowing them to store logic states just like standard field-effect transistors.

In the picture above, the scale bar indicates 20 nanometers, but Novoselov claims the team's recently created one nanometer graphene transistor could represent the end of the line for Moore's Law.

"It's about the smallest you can get," said Novoselov.

With the creation of what could be the smallest possible transistor, the long line of technology that extends from the first transistor, created at Bell Labs in 1947 and (a replica of which is pictured at left), could come to an end.

For all the new transistors' promise, Novoselov noted that it is currently impossible to produce large amounts of graphene. They can only produce graphene crystals about 100 microns or 0.1 millimeters across, far too small for industrial production at Intel's scale. But the scientist believes that a process for producing graphene wafers is already in the foreseeable future.
"Probably this problem will be solved in the next couple of years," he said.
Image 1: Courtesy Mesoscopic Physics group at the University of Manchester
Image 2: Public domain image

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