IBM proves nanotubes can beat silicon

IBM has improved its carbon nanotube (CNT) transistors to the point where they can outperform the most advanced silicon transistors in prototype today, it said Monday.

CNTs are tube-shaped molecules made of carbon atoms, one nanometer (around three atoms) thick and 50,000 times thinner than a human hair, IBM Research Scientist Shalom Wind said in an interview.

Scientists from IBM's T.J. Watson Research Center in Yorktown Heights, New York, have achieved the highest transconductance (a measure of current-carrying capability) of any CNT transistor to date, and more than twice the transconductance, per unit width, of the top-performing silicon transistors available, IBM said.

CNTs are expected to replace silicon when chip development hits the physical barrier where silicon just can't be made any smaller, in about 10 to 15 years, IBM said.

Wind was lead author, along with colleagues Joerg Appenzeller, Richard Martel, Vincent Derycke and Phaedon Avouris, of an article published in Monday's Applied Physics Letters journal describing the effects of "Vertical scaling in carbon nanotube field-effect transistors using top gate electrodes."

The research involved creating carbon nanotube field-effect transistors (CNFETs) with a similar structure to conventional metal-oxide semiconductor field-effect transistors (MOSFETs). That allowed the CNTs to be compared with their silicon equivalent, IBM said.

The devices showed excellent electrical characteristics, turning on and off easily and conducting well at low voltages. Previous attempts at CNT transistors needed high voltages of up to 20 volts to turn on and off, Wind said, compared to the 1 volt used for silicon.

These previous transistor attempts were based on a silicon wafer, using the silicon itself as the gate or switch to control the flow of electricity. That worked, but meant all of the transistors had to be turned on and off at the same time, he said.

The new structure puts the gate on top of the nanotube with a thin insulating layer of silicon dioxide in between, "so that it looks just like a silicon transistor, but with a narrow nanotube instead of a flat sheet of silicon," Wind said.

The new carbon nanotube transistor can turn on with power of 1 volt or less, as a result of the insulating layer, and operate independently.

"Imagine we had previously developed a new type of light bulb that worked, but needed high voltages, wasn't very bright, and you have to turn on all the lights in your house at once. Now we can make them brighter, using less power, and turn them on and off individually."

This research takes carbon nanotube technology a step closer to becoming a viable option for replacing silicon, Wind said.

"It's one thing to develop lots of little devices using new technology, but if they don't operate as well as older technology it's not worth it. But it looks like these operate even better than the silicon transistors being developed, and that's pretty exciting."

The CNFETs have yet to be optimized, with a thinner silicon dioxide layer and shorter channel lengths (so that the electrons don't have to travel so far), so Wind expects even better results to be produced in future.

Not that carbon nanotube transistors will be in the shops anytime soon, Wind stressed. Researchers still have to find ways to control how the carbon nanotubes are placed in specific places so that they work properly, and there are "subtle issues in terms of how the current gets in and out. It's slightly different to how it works in silicon and we're trying to understand that."

Getting nanotube technology up to speed before silicon meets its physical limits will be "tricky," but the latest research is one step further towards that goal, Wind said.

Join the newsletter!

Error: Please check your email address.
Rocket to Success - Your 10 Tips for Smarter ERP System Selection
Keep up with the latest tech news, reviews and previews by subscribing to the Good Gear Guide newsletter.

Gillian Law

Computerworld
Show Comments

Most Popular Reviews

Latest Articles

Resources

PCW Evaluation Team

Sarah Ieroianni

Brother QL-820NWB Professional Label Printer

The print quality also does not disappoint, it’s clear, bold, doesn’t smudge and the text is perfectly sized.

Ratchada Dunn

Sharp PN-40TC1 Huddle Board

The Huddle Board’s built in program; Sharp Touch Viewing software allows us to easily manipulate and edit our documents (jpegs and PDFs) all at the same time on the dashboard.

George Khoury

Sharp PN-40TC1 Huddle Board

The biggest perks for me would be that it comes with easy to use and comprehensive programs that make the collaboration process a whole lot more intuitive and organic

David Coyle

Brother PocketJet PJ-773 A4 Portable Thermal Printer

I rate the printer as a 5 out of 5 stars as it has been able to fit seamlessly into my busy and mobile lifestyle.

Kurt Hegetschweiler

Brother PocketJet PJ-773 A4 Portable Thermal Printer

It’s perfect for mobile workers. Just take it out — it’s small enough to sit anywhere — turn it on, load a sheet of paper, and start printing.

Matthew Stivala

HP OfficeJet 250 Mobile Printer

The HP OfficeJet 250 Mobile Printer is a great device that fits perfectly into my fast paced and mobile lifestyle. My first impression of the printer itself was how incredibly compact and sleek the device was.

Featured Content

Latest Jobs

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?