IBM Research has developed a new way of creating contacts for carbon nanotube that it claims will open "a pathway to dramatically faster, smaller and more powerful computer chips beyond the capabilities of traditional semiconductors". The process involves rolling nanoscale tubes from sheets of graphene measuring just one atom thick and could give new life to Moore's Law.
The results, published in the journal Science, describe a new method for creating contacts for carbon nanotubes that -- unlike existing methods for both carbon and silicon transistors -- doesn't suffer from the problem of increased electrical resistance as the contact is reduced in size. Increased electrical resistance in a transistor results in performance reductions, meaning that, until now, smaller contacts would result in slower processors.
To overcome the problem, IBM developed an entirely new metallurgical process that chemically binds metal atoms to the carbon atoms at the end of the nanotubes. IBM said that this 'end-bonded contact scheme' allowed "the contacts to be shrunken down to below 10 nanometres without deteriorating performance of the carbon nanotube devices". This means we could see carbon nanotube processors "within the decade."
But the company isn't there yet. In a Q&A posted on the IBM Research blog, Nanoscale device and technology manager Shu-Jen Han explained what still needed to be done in order to use carbon nanotube transistors in a viable processor: "We've developed a way for carbon nanotubes to self-assemble and bind to specialised molecules on a wafer. The next step is to push the density of these placed nanotubes (to 10 nm apart) and reproducibility across an entire wafer."
The problem with existing silicon-based transistors -- the tiny switches that carry information on current computer chips -- is that the material properties of silicone limit the degree to which transistors can be reduced in size. IBM has built functional silicon-germanium transistors at 7 nanometres, but say that this pushes the limits of what the can be done with the material, while Intel has stated that it won't be using silicon beyond the 10nm scale -- current Intel CPUs are at 14nm, and the next generation will be 10nm.
The properties of carbon nanotubes make them ideal for use in computing: they conduct electricity faster than silicon, use less power and, measuring just one nanometer thick, are much thinner than current silicon, which makes them less prone to unwanted electrostatic discharge.
IBM has been investing heavily in carbon nanotube research, and has already shown that carbon nanotube transistors can be used as excellent switches at channel dimensions of less than 10nm: "the equivalent to 10,000 times thinner than a strand of human hair and less than half the size of today’s leading silicon technology", the company explained.
Writing on IBM's A Smarter Planet blog, vice president of science and technology Dario Gil said the new technology could extend the life of Moore's Law. Coined in the 1960s, Gordon Moore's fundamental axiom of modern technological development postulated that the number of transistors that can be put onto a computer chip will double every two years. And with silicon reaching its physical limits, the success of carbon nanotube research will be essential if that trend is to continue.
This article was originally published by WIRED UK
