Graphite Derivitive May Make Smaller, Faster Computer Chips

May 29th, 2008

We have seen computers reach astounding speeds, and you can’t even keep up with how quickly they actually do speed up. Things are quite different from the first Windows 3.1 computer I had, or even looking back to the days as a child when i had the Vic 20, Commodore 64 and 128. Today we aren’t as limited by producing processing speed as we are trying to figure out how to make those chips smaller so that we can stuff more power into a smaller space while we lounge in our teak furniture, or anywhere else on the planet.

Researchers predict that silicon chips will reach their maximum shrinking point within the next decade. This has prompted a search for materials to replace silicon as transistors continue to shrink in accordance with Moore’s Law, which predicts that the number of transistors on a chip will double every two years. Graphene, a form of carbon derived from graphite, is one of the materials being considered.

Hongjie Dai, the J. G. Jackson and C. J. Wood Professor of Chemistry, has made transistors called “field-effect transistors”—a critical component of computer chips—with graphene that can operate at room temperature.

“For graphene transistors, previous demonstrations of field-effect transistors were all done at liquid helium temperature, which is 4 Kelvin [-452 Fahrenheit],” said Dai, the lead investigator. His group’s work is described in a paper published online in the May 23 issue of the journal Physical Review Letters.

Their research has shown that these carbon based nanotubes outperform silicon in speed by a factor of two, the problem is that not all of the tubes, which can have 1-nanometer diameters, are semiconducting, Dai said. “Depending on their structure, some carbon nanotubes are born metallic, and some are born semiconducting,” he said. “Metallic nanotubes can never switch off and act like electrical shorts for the device, which is a problem.”

On the other hand, Dai’s team demonstrated that all of their narrow graphene nanoribbons made from their novel chemical technique are semiconductors. “This is why structure at the atomic scale—in this case, width and edges—matters,” he said.