Scientists have taken a new step toward building tiny computers, creating an array of carbon tubes just a few molecules in diameter.
Nanotubes are sheets of carbon atoms rolled into a tube.
In different forms they can conduct electricity like a metal or can be semiconducting. A team headed by Philip G. Collins at IBM's Watson Research Center in Yorktown Heights, N.Y., developed a method to control the conductivity of multi-walled nanotubes that connect electrodes. The group reports in Friday's issue of the journal Science that they were able to selectively destroy some of the layers by running extremely high currents through them in air. This allowed them to tailor nanotubes to be either semiconducting or metallic, and to assemble whole arrays of field-effect nanotube transistors. In the second paper in the same journal, Min Ouyang and colleagues at Harvard University report on studies of single-wall nanotubes.