YORKTOWN HEIGHTS, N.Y.--Scientists at IBM Corp. today reported a major breakthrough in development of transistor technology using carbon nanotubes as a potential replacement for today's mainstream silicon circuits. The researchers believe the development could help clear the way for production of ICs once solid-state physics runs out of gas in silicon during the next 10 to 20 years.

The scientists said they have used a new technique to built the world's first array of transistors out of carbon nanotubes, which are tiny cylinders of carbon atoms measuring 10 atoms across. These structures are about 500 times smaller than today's silicon transistors, said IBM.

The breakthrough, according to a paper appearing in the April 27 issue of Science, is the development of a process that's faster than techniques used to manipulate individual nanotubes in building bundles of desired structures for circuits.

"This is a major step forward in our pursuit to build molecular scale electronic devices," said Phaedon Avouris, lead researcher on the project and manager of IBM's Nanoscale Science Research Department. "Our studies prove that carbon nanotubes can compete with silicon in terms of performance, and since they may allow transistors to be made much smaller, they are promising candidates for a future nanoelectronic technology."

IBM said the breakthrough overcomes the slow process of manipulating individual nanotubes so that they can be separated with useful electrical properties. IBM scientists call their technique "constructive destruction."

The size and shape of carbon nanotubes determines their electronic properties as being either metallic or semiconducting. The problem has been that all synthetic methods of production yield a mixture of metallic and semiconducting nanotubes that "stick together" in bundles. This prevents their use as transistors, according to IBM.

The scientists created a technique to construct a dense array of semiconducting nanotubes while destroying the metallic nanotubes, according to IBM. An electric shockwave is used to destroy the metallic nanotubes, leaving only the semiconducting nanotubes for building transistors.

IBM scientists also reported that they were able to remove individual carbon shells of a multi-walled nanotube to fabricate carbon nanotubes with the precise electrical properties needed for circuits. Researchers said they have been able to fabricate field-effect transistors (FETs) from carbon nanotubes with any variable band-gap desired.

Researchers are also working on improving the electrical characteristics of individual nanotubes. Data shows that if carbon nanotubes were scaled up to the size of today's silicon transistors, they would perform at the same level as current semiconductors, according to IBM. Consequently, IBM said, it now appears that smaller carbon nanotube transistors could enable Moore's Law to continue even when the chip industry hits the limitations of silicon materials.