Nanotechnology Now

Our NanoNews Digest Sponsors





Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > Carbon nanotube avalanche process nearly doubles current

Photo by L. Brian Stauffer
Electrical and computer engineering professor Eric Pop, from left, worked with undergraduate Yang Zhao and graduate student Albert Liao, both in ECE, to demonstrate a remarkable increase in the current-carrying capacity of carbon nanotubes.
Photo by L. Brian Stauffer
Electrical and computer engineering professor Eric Pop, from left, worked with undergraduate Yang Zhao and graduate student Albert Liao, both in ECE, to demonstrate a remarkable increase in the current-carrying capacity of carbon nanotubes.

Abstract:
By pushing carbon nanotubes close to their breaking point, researchers at the University of Illinois have demonstrated a remarkable increase in the current-carrying capacity of the nanotubes, well beyond what was previously thought possible.

Carbon nanotube avalanche process nearly doubles current

Champaign, IL | Posted on February 9th, 2009

The researchers drove semiconducting carbon nanotubes into an avalanche process that carries more electrons down more paths, similar to the way a multilane highway carries more traffic than a one-lane road.

"Single-wall carbon nanotubes are already known to carry current densities up to 100 times higher than the best metals like copper," said Eric Pop, a professor of electrical and computer engineering at the U. of I. "We now show that semiconducting nanotubes can carry nearly twice as much current as previously thought."

As reported in the journal Physical Review Letters, the researchers found that at high electric fields (10 volts per micron), energetic electrons and holes can create additional electron-hole pairs, leading to an avalanche effect where the free carriers multiply and the current rapidly increases until the nanotube breaks down.

The sharp increase in current, Pop said, is due to the onset of avalanche impact ionization, a phenomenon observed in certain semiconductor diodes and transistors at high electric fields, but not previously seen in nanotubes.

While the maximum current carrying capacity for metallic nanotubes has been measured at about 25 microamps, the maximum current carrying capacity for semiconducting nanotubes is less established. Previous theoretical predictions suggested a similar limit for single-band conduction in semiconducting nanotubes.

To study current behavior, Pop, graduate student Albert Liao and undergraduate student Yang Zhao first grew single-wall carbon nanotubes by chemical vapor deposition from a patterned iron catalyst. Palladium contacts were used for measurement purposes. The researchers then pushed the nanotubes close to their breaking point in an oxygen-free environment.

"We found that the current first plateaus near 25 microamps, and then sharply increases at higher electric fields," said Pop, who also is affiliated with the Beckman Institute and the Micro and Nanotechnology Laboratory at the U. of I. "We performed repeated measurements, obtaining currents of up to 40 microamps, nearly twice those of previous reports."

By inducing very high electric fields in the nanotubes, the researchers drove some of the charge carriers into nearby subbands, as part of the avalanche process. Instead of being in just one "lane," the electrons and holes could occupy several available lanes, resulting in much greater current.

The avalanche process (which cannot be observed in metallic carbon nanotubes because an energy gap is required for electron-hole multiplication) offers additional functionality to semiconducting nanotubes, Pop said. "Our results suggest that avalanche-driven devices with highly nonlinear turn-on characteristics can be fashioned from semiconducting single wall nanotubes."

Funding was provided by the National Science Foundation and the National Institute of Standards and Technology through the Nanoelectronics Research Initiative.

####

For more information, please click here

Contacts:
James E. Kloeppel
Physical Sciences Editor
217-244-1073


Eric Pop
217-244-2070

Copyright © University of Illinois at Urbana-Champaign

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Using ultrathin sheets to discover new class of wrapped shapes: UMass Amherst materials researchers describe a new regime of wrapped shapes August 31st, 2015

New material science research may advance tech tools August 31st, 2015

Efficiency of Nanodrug Containing Antibiotics in Treatment of Infectious Diseases Evaluated August 31st, 2015

Researchers use DNA 'clews' to shuttle CRISPR-Cas9 gene-editing tool into cells August 30th, 2015

Govt.-Legislation/Regulation/Funding/Policy

An engineered surface unsticks sticky water droplets August 31st, 2015

New material science research may advance tech tools August 31st, 2015

Seeing quantum motion August 30th, 2015

Artificial leaf harnesses sunlight for efficient fuel production August 30th, 2015

Chip Technology

Nanometrics to Participate in the Citi 2015 Global Technology Conference August 26th, 2015

Kwansei Gakuin University in Hyogo, Japan, uses Raman microscopy to study crystallographic defects in silicon carbide wafers August 25th, 2015

A little light interaction leaves quantum physicists beaming August 25th, 2015

'Magic' sphere for information transfer: Professor at the Lomonosov Moscow State University made the «magic» sphere for information transfer August 24th, 2015

Nanotubes/Buckyballs/Fullerenes

Developing Component Scale Composites Using Nanocarbons August 26th, 2015

Southampton scientists find new way to detect ortho-para conversion in water August 25th, 2015

Revolutionary MIT-Developed Nanotechnology Company Showcases at CAMX in Dallas August 20th, 2015

Engineering a better 'Do: Purdue researchers are learning how August 4th, 2015

Nanoelectronics

Nanotechnology that will impact the Security & Defense sectors to be discussed at NanoSD2015 conference August 25th, 2015

'Quantum dot' technology may help light the future August 19th, 2015

Surprising discoveries about 2-D molybdenum disulfide: Berkeley Lab researchers use award-winning campanile probe on promising semiconductor August 15th, 2015

Better together: Graphene-nanotube hybrid switches August 3rd, 2015

Discoveries

Using ultrathin sheets to discover new class of wrapped shapes: UMass Amherst materials researchers describe a new regime of wrapped shapes August 31st, 2015

An engineered surface unsticks sticky water droplets August 31st, 2015

New material science research may advance tech tools August 31st, 2015

Efficiency of Nanodrug Containing Antibiotics in Treatment of Infectious Diseases Evaluated August 31st, 2015

Announcements

Using ultrathin sheets to discover new class of wrapped shapes: UMass Amherst materials researchers describe a new regime of wrapped shapes August 31st, 2015

An engineered surface unsticks sticky water droplets August 31st, 2015

New material science research may advance tech tools August 31st, 2015

Efficiency of Nanodrug Containing Antibiotics in Treatment of Infectious Diseases Evaluated August 31st, 2015

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







Car Brands
Buy website traffic