Nanotechnology Now

Our NanoNews Digest Sponsors





Heifer International

Wikipedia Affiliate Button


android tablet pc

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

Industrial Nanotech, Inc. to Publish PCAOB Audited Financials July 31st, 2014

Nanostructured metal-oxide catalyst efficiently converts CO2 to methanol: Highly reactive sites at interface of 2 nanoscale components could help overcome hurdle of using CO2 as a starting point in producing useful products July 31st, 2014

Carnegie Mellon Chemists Create Nanofibers Using Unprecedented New Method July 31st, 2014

Pressure probing potential photoelectronic manufacturing compound July 31st, 2014

Govt.-Legislation/Regulation/Funding/Policy

Study finds physical link to strange electronic behavior: Neutron measurements offer new clues about iron-based superconductor July 31st, 2014

Nanostructured metal-oxide catalyst efficiently converts CO2 to methanol: Highly reactive sites at interface of 2 nanoscale components could help overcome hurdle of using CO2 as a starting point in producing useful products July 31st, 2014

Carnegie Mellon Chemists Create Nanofibers Using Unprecedented New Method July 31st, 2014

Pressure probing potential photoelectronic manufacturing compound July 31st, 2014

Chip Technology

Pressure probing potential photoelectronic manufacturing compound July 31st, 2014

Nanometrics Reports Second Quarter 2014 Financial Results July 30th, 2014

A*STAR and industry form S$200M semiconductor R&D July 25th, 2014

A Crystal Wedding in the Nanocosmos July 23rd, 2014

Nanotubes/Buckyballs

SouthWest NanoTechnologies Names NanoSperse as A SWeNT Certified Compounder July 29th, 2014

A new way to make microstructured surfaces: Method can produce strong, lightweight materials with specific surface properties July 29th, 2014

UCF Nanotech Spinout Developing Revolutionary Battery Technology: Power the Next Generation of Electronics with Carbon July 23rd, 2014

University of Houston researchers create new method to draw molecules from live cells: Technique using magnetic nanomaterials offers promise for diagnosis, gene therapy July 17th, 2014

Nanoelectronics

A*STAR and industry form S$200M semiconductor R&D July 25th, 2014

A Crystal Wedding in the Nanocosmos July 23rd, 2014

3-D nanostructure could benefit nanoelectronics, gas storage: Rice U. researchers predict functional advantages of 3-D boron nitride July 15th, 2014

IBM Announces $3 Billion Research Initiative to Tackle Chip Grand Challenges for Cloud and Big Data Systems: Scientists and engineers to push limits of silicon technology to 7 nanometers and below and create post-silicon future July 10th, 2014

Discoveries

Study finds physical link to strange electronic behavior: Neutron measurements offer new clues about iron-based superconductor July 31st, 2014

Nanostructured metal-oxide catalyst efficiently converts CO2 to methanol: Highly reactive sites at interface of 2 nanoscale components could help overcome hurdle of using CO2 as a starting point in producing useful products July 31st, 2014

Carnegie Mellon Chemists Create Nanofibers Using Unprecedented New Method July 31st, 2014

Pressure probing potential photoelectronic manufacturing compound July 31st, 2014

Announcements

Industrial Nanotech, Inc. to Publish PCAOB Audited Financials July 31st, 2014

Nanostructured metal-oxide catalyst efficiently converts CO2 to methanol: Highly reactive sites at interface of 2 nanoscale components could help overcome hurdle of using CO2 as a starting point in producing useful products July 31st, 2014

Carnegie Mellon Chemists Create Nanofibers Using Unprecedented New Method July 31st, 2014

Pressure probing potential photoelectronic manufacturing compound July 31st, 2014

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







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE