Jun 102011
Rotating view of a graphite crystal (2 graphen...

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I.B.M. researchers said Thursday that they had designed high-speed circuits from graphene, an ultra-thin material that has a host of promising applications, from high-bandwidth communication to a new generation of low-cost smartphone and television displays.

The I.B.M. advance, which the researchers reported in the journal Science, is a circuit known as a broadband frequency mixer that was built on a wafer of silicon. Widely used in all kinds of communications products, the circuits shift signals from one frequency to another.

In the Science paper, the I.B.M. researchers describe a demonstration in which they deposited several layers of graphene on a silicon wafer, then created circuits based on graphene transistors and components known as inductors. They demonstrated frequency mixing up to speeds of 10 gigahertz.

In the past I.B.M. has created stand-alone graphene transistors, but not complete electronic circuits.

Scientists began making flakes of graphene, an atomic-scale lattice of carbon atoms, in the 1970s. They have gradually refined the process so they can now produce films of the material that are just a single atom thick. The film arranges itself in a hexagon-shaped array of carbon atoms and has the advantages of being flexible, transparent and inexpensive to manufacture.

But it is not yet a candidate to replace today’s CMOS transistors, the basis for the microprocessors and computer memories in consumer electronics systems. Graphene does not have the same physical properties as semiconducting materials and cannot be used to completely switch on and off in the way that logic transistors are meant to do.

That has not tempered the industry’s excitement over potential applications for the material. In Europe and Asia, government and corporate investments are running far in advance of those in the United States, said Phaedon Avouris, an I.B.M. chemical physicist who is a leader of the company’s research effort.

“Outside the U.S. there is a lot of interest,” he said.

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