Cambridge scientists develop new method for producing carbon nanotubes

Scientists working in the field of nanotechnology have stumbled upon a discovery which could revolutionise computing. The breakthrough, made by a team at the Department of Engineering, could now speed the increase in the processing power of silicon chips considerably, thereby breaking Moore's Law, the axiom which states that processing power doubles every 18 months while the cost remains constant.

Since its first discovery in 1991, the existence of a new form of carbon as nanotubes has excited scientists the world over. Carbon in the form of nanotubes has the potential to form a material of great mechanical strength (a hundred times stronger than steel) as well as displaying remarkable electrical properties (depending on the arrangement of their carbon atoms, they can either be conducting, insulating or act as semi-conductors). These electrical properties and the tubes' tiny size (10,000 times less than a human hair) make them ideal for the miniaturisation and speeding up of electronic circuits.

The stumbling block to date has been how to fabricate the tubes in such a way to produce the required properties. All the known methods of fabrication produced a disordered mass of tubes with correspondingly random structures and properties.

That is all about to change, with a major breakthrough made in the Department's Nanoscale Science Laboratory (NSL) headed by Professor Mark Welland, in conjunction with Professor Jim Gimzewski at UCLA and Dr Maria Seo at IBM, Zurich. Having discovered how to fabricate single crystals of carbon nanotubes in neatly ordered arrays, they have opened the way to the development of practical applications from this unique form of carbon.

"Our findings were totally unexpected - it was one of those amazing results that happens almost by chance," explained Dr Colm Durkan, a lecturer in the Department of Engineering. "We were actually trying to fill nanotubes with metal, using a technique that had been reported elsewhere when we realised that we had succeeded in producing arrays of perfect nanotubes, something that has not been achieved before.

"We discovered that by using fullerene molecules as the starting point for growing nanotubes, and then adding a suitable catalyst and heating to 900 degrees centigrade, we can produce arrays of aligned carbon nanotubes, all with identical properties. These are single crystals of carbon in a new form.

"That means we now have the technology to fabricate nanotubes with the electrical and mechanical properties that we require, and we can position them where we want and at any orientation. This is also a major step towards being able to produce carbon nanotubes as a bulk material, and we can already begin to investigate many different applications for the material."

Described by other workers in the field as the most stunning result in 'buckytube' research in a year, the team's findings have left them speechless.

"It was so unexpected to fabricate perfect crystalline arrays of nanotubes in this way, when all previous attempts have shown nanotubes wrapped together looking like a plate of spaghetti," says Professor Mark Welland.

"We couldn't believe it at first, and it took six months before we were convinced that what we were seeing was real. I am still amazed at the beautiful images of these crystals."

The team will now continue their research into the electrical and mechanical properties of the various crystalline forms of the new material, and will look towards developing applications.

Further information
For further information go to the website of the Nanoscale Science Laboratory:
www-g.eng.cam.ac.uk/na no