New Carbon Nanotube Chip Outperforms Silicon Semiconductors (nanotechweb.org)

"Researchers at the University of Wisconsin-Madison are the first to have fabricated carbon nanotube transistors (CNTs) that outperform the current-density of conventional semiconductors like silicon and gallium arsenide," reports NanotechWeb. Slashdot reader wasteoid shares the site's interview with one of the researchers: "When the transistors are turned on to the conductive state (meaning that current is able to pass through the CNT channel) the amount of current traveling through each CNT in the array approaches the fundamental quantum limit," he tells nanotechweb.org.

"Since the CNTs conduct in parallel, and the packing density and conductance per tube are very high, the overall current density is very high too -- at nearly twice that of silicon's. The result is that these CNT array FETs have a conductance that is seven times higher than any previous reported CNT array field-effect transistor."
The research was funded in part by the U.S. Army and Air Force, as well as the National Science Foundation. "The implication here is that by replacing silicon with a CNT channel, it should be possible for us to make either a higher performing device or one that works at lower power."

In other news, Fujitsu announced this week that it's joining an effort to release a 256-megabyte 55-nanometer carbon nanotube-based NRAM by 2018.

Comments

It will happen. But it won't be easy.

[Richard Kirk]

At the moment the sensible money is on silicon. Make silicon circuits 10% smaller or 10% after and the whole of electronics benefits. If you try to do the same thing with carbon, then you have to re-invent many of the fabrication processes from scratch before you can make a single useful gadget.

In the long term, carbon is a no-brainer. It has a huge band gap will lets it be stable at high temperatures. It can bond to itself and be a super-resistor, a resistor, a semiconductor, and a conductor. Down the middle of carbon tubes it may even manage to be a superconductor. You could make a memory element using a few tens of atoms. Can you imagine having a mole of bits? On the other hand, trying to make a conductive track by doping silicon gets harder and harder as the size drops, and there are problems getting the current to turn corners in a single crystal.

So, what do we do in the middle-term? We can make something that is probably bigger than is ideal using the existing silicon technology. We will find a niche market that needs the same simple thing replicated lots of times - and non-volatile memory is the obvious choice - and leave making a carbon microprocessor for when we have more of the other bits working. That is what people have been predicting for years, and now they are actually beginning to do it.

Why are they dong it now? Well, I can remember over the past 40-odd years people saying you cannot get Si fabrication much below 10 microns, and then there were limits making them below 1 micron, and then you absolutely could no get below 0.1 micron. And as long as Silicon technology oprogressed, it was the better short-term investment. But as we go on, the next-generation silicon plants will be more expensive, the rewards are getting smaller, and the chances of some unexpected breakthrough dwindle. It is a good time for something to give.