World's thinnest material yields semiconductor breakthrough

By Stephen Withers
Friday, 02 March 2007 01:11

Home IT

The successful creation of transistors made from graphene - a form of carbon that is just one atom thick - may provide the microelectronics industry with a continuing path for miniaturisation when silicon technology reaches its lower limit.

Researchers at Britain's University of Manchester originally created graphene transistors two years ago, but at that stage the transistors were unable to completely switch off the current. The new development produces transistors that are suitable for use computers and other devices.

The significance of the breakthrough is that graphene remains stable and conductive even in strips that are just a few nanometres wide. Silicon and all other known materials become unstable in strips a few tens of nanometres wide. Semiconductor companies currently use 45 nanometre silicon technology, so there is little room left for continued miniaturisation.

Future electronic circuits can be carved out of a single graphene sheet.

The Manchester technology is far from ready to go into production. "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," said lead researcher Leonid Ponomarenko.

Andre Geim, director of the Manchester Centre for Mesoscience and Nanotechnology, suggests graphene-based circuits will not come into their own before 2025.

He believes graphene is the only viable successor to silicon: "This material combines many enticing features from other technologies that have been considered as alternatives to the silicon-based technology," he said. "Graphene combines most exciting features from carbon-nanotube, single-electron and molecular electronics, all in one."

Geim led the team that originally discovered graphene.

The everyday forms of carbon are graphite (where the atoms are arranged in 'sheets' with weak bonds between the layers, giving rise to its lubricant properties) and diamond (where they form a regular and very strong crystal lattice). Researchers liken the arrangement of the atoms in graphene to chicken wire, but with a slight undulation in the third dimension that gives strength to the structure.

Other possible applications for the material include improving the definition of electron microscope images, and separating gases with a molecular sieve.