August 27, 2001 – Armonk, NY – IBM Corp. claims its scientists have built the smallest-ever computer logic circuit, a two-transistor component made from a single molecule of carbon.
The material used to construct the circuit is a carbon nanotube, a hollow strand 100,000 times thinner than a human hair.
Because of the exceptional strength and semiconducting capabilities of carbon nanotubes, they have been considered by researchers at IBM as the material that offers the most promise for replacing silicon, the principal ingredient that makes up transistors and microprocessors, or computer chips.
“In the future we should be able to make them by the millions,” said Phaedon Avouris, manager of nanoscale science in IBM’s research division.
The microscopic — but simple — logic circuit brings closer the goal of creating the first microprocessor using carbon nanotube technology, which will allow computers to become even smaller while running faster and consuming less power, Avouris said.
Avouris believes that Moore’s Law will be thwarted by the physical limits of silicon chip technology.
Avouris predicts silicon’s physical barrier will be reached in 10 to 15 years, when it won’t be able to shrink any more. Most gains in computer processing power come from the shrinking of transistors and logic circuits, which gives electrons a shorter path to travel, making processors run faster.
When that happens, IBM believes that carbon nanotubes will take over, allowing for smaller processors with more transistors.
“They’ll be able to substitute all the functions that silicon performs today, perhaps even more, because of their size,” Avouris said.
Other researchers say IBM’s discovery is no more important than other innovations aimed at moving semiconductors beyond silicon.
“It’s a good piece of science,” said Stanley Williams, a research fellow at Hewlett-Packard Laboratories in Palo Alto, CA. “Is it, all by itself, revolutionary? No. There are lots of people contributing in this area.”
The carbon nanotube, discovered in 1991 by Japan’s NEC Corp., is a single-molecule strand of carbon constructed of atoms linked in chicken wire-like formations. The nanotubes measure 1-2 nanometers – billionths of a meter – in diameter and as long as a millimeter, Avouris said, adding that the tiny tubes are about 10 times stronger than steel.
The nanotube logic circuit constructed by Avouris and three other IBM researchers is made up of a pair of transistors – one positive, one negative. It marks the second of three major steps toward building a replacement for the silicon-based computer microprocessor, according to IBM.
The first step came in 1998, when scientists – including researchers at IBM and NEC – created nanotube transistors.
The final step is the linking together of many transistor-embedded logic circuits into a microprocessor that can perform complex calculations.
Avouris said IBM is a decade or more away from incorporating nanotube technology in any of its products.