Carbon Nanotubes May Mean Tiny Computer Chips

07 September 2001

Reaching a long-sought goal in computing research, scientists have created a computer circuit based on a single molecule, which could lead one day to far smaller and faster computer chips that use less power.

International Business Machines Corp. said Sunday that its researchers have built a logic circuit -- a set of electronic components that performs a processing function -- based on a tiny cylindrical structure made up of carbon atoms that is about 100,000 times thinner than a human hair. The breakthrough is IBM's second this year using the molecules called carbon nanotubes as semiconductors, making them an increasingly viable alternative to silicon, which forms the base of current chips, IBM said.

“Carbon nanotubes are now the top candidate to replace silicon when current chip features just can't be made any smaller,” said IBM's Phaedon Avouris, lead scientist on the project. ”Such beyond-silicon nanotube electronics may then lead to unimagined progress in computing miniaturization and power.'' Scientists are looking for a replacement for silicon because in the next 10 to 15 years they expect that it will no longer be possible to reduce the size of chips using silicon, which will limit improvements in chip size and speed.

In a couple of years, IBM expects to start working on ways of building the new chips and will know how the size of the elements in the nanotube chip compare with those of silicon chips. While researchers had already found a way to form nanotubes into transistors, IBM's latest achievement showed that a nanotube can be used to make a logic circuit, the key to computing. IBM scientists used a nanotube to make a 'NOT' gate, which has both a positive and negative transistor, meaning that the entire circuit can perform the processing functions critical to computing.

A carbon nanotube is a single molecule that's about 500 times narrower than the silicon used in today's processor and is about 10 atoms across. In addition, a nanotube creates less heat than silicon and uses less power and space.

IBM said a nanotube circuit's signal output is strong enough to drive other gates or circuits, which means that more complex circuits could be built using a single nanotube. These complex circuits are the next step toward molecular computer chips, IBM said. IBM hopes to begin to develop the carbon nanotubes in two years, although it will be another 10 to 15 years before a product hits the market.

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