IBM researchers take organic approach to technology

IBM researchers have built the first elementary computing circuit around a single carbon nanotube molecule, a material that holds great promise and may one day replace traditional silicon. The work pushes the feasibility of using individual molecules to build future generations of sophisticated microelectronic devices to new heights.

The researchers believe that the new technique will aid in simplifying the semiconductor manufacturing process, as well as provide a foundation to test the logic gate conductor in several electronics applications, including PC processors.

IBM’s work is a milestone because the type of circuit the researchers built — called a ring oscillator — acts like a speedometer to evaluate the electrical current flowing through the nanotube. Circuit speeds were a million times faster than previously demonstrated experimental circuits.

At the moment, the circuit is slower than currently available silicon chips. However, researchers believe new nanofabrication processes may reveal the performance potential of carbon nanotube electronics.

“We are exploring moving beyond silicon-based chips to significantly boost the performance of PCs,” said IBM research staff member Joerg Appenzeller in a Sci-Tech Today press release. “Silicon chips will continue to improve, but we need to look ahead decades into the future.”

Carbon nanotubes are well suited for electronic processors because there is no resistance to electric current, significantly increasing the speed at which currents are switched on and off.

Researchers are now focusing on constructing carbon nanotube transistors and recent breakthroughs at IBM demonstrate the potential of carbon nanotubes in nanochip fabrications.

Carbon nanotubes are microscopic in size, about 50,000 times thinner than a human hair. Their unique electron current properties might allow them to carry more current than present silicon based transistors, and their smaller size will allow further miniaturization of microchips.

“Carbon nanotubes are now the top candidate to replace silicon when current chip features just can’t be made any smaller,” remarked Phaedon Avouris in a Chemical & Engineering News press release. Avouris is co-author of the study and manager of nanometer-scale science and technology at IBM’s T. J. Watson Research Center in Yorktown Heights, N.Y.

Because of their superior strength and agility, carbon nanotubes are already used as composite fibers in materials ranging from plastics to concrete. IBM plans to use nanotube devices to test new carbon nanotube transistors and circuits.