IBM researchers reported on Friday they have made a breakthrough in transistor technology by building what they claim is the first array of transistors made out of carbon nanotubes.

The material can be used to make computer chips when silicon-based chips cannot be made any smaller - a critical breakthrough answering a problem chip makers will have to cope with in the next 10 to 20 years, according to IBM officials.

According to Moore's Law, a principle laid down by Gordon Moore, one of the guiding forces behind Intel, the number of transistors that can be crammed on to a chip doubles every 18 months. But in the next 10 to 20 years, some believe silicon will reach its physical limits and wafers will no longer be able to include more transistors.

"We see this as a major step forward in our pursuit to build molecular scale electronic devices," said Phaedon Avouris, lead researchers on the project. "I think our studies prove that carbon nanotubes can compete with silicon in terms of performance," he said.

Carbon nanotubes are tiny cylinders of carbon atoms measuring 10 atoms across and are 500 times smaller than today's silicon-based transistors and reportedly 1,000 times stronger than steel.

The breakthrough achieved by IBM scientists bypasses several tedious and intensive nanotube manipulation processes.

The electrical properties of carbon nanotubes are either metallic or semiconducting. In the past, explained an IBM spokesperson, scientists had problems using them as transistors because all synthetic methods of production yield a mix of metallic nanotubes that would stick together, rendering them unusable.

IBM researchers overcame this problem with a 'constructive destruction' technique that allows them to produce only semiconducting nanotubes with the electrical properties necessary to build chips, the spokesperson said.