Findings: Door opens with 'Not gate'

Scientists have taken an important step towards a molecular computer, a machine that uses single molecules to store and manipulate data.

Phaedon Avouris's team at the IBM/ Watson Research Center, Yorktown Heights, United States, have created a "Not gate", one of the three basic elements that every computer requires to process data and take decisions, using single-wall carbon nanotubes 100,000 times thinner than a human hair.

These nanotubes possess electrical characteristics that make them the best material yet for nanoelectronics.

Avouris created a Not gate by dispersing nanotubes on a silicon substrate and then covering them with an insulating layer.

Windows were cut through the layer using an electron beam and then either potassium was evaporated through them or the wafer was tempered and then exposed to oxygen. This created an alternating sequence of n-and p-type transistors.