Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

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

Researchers use sound waves to advance optical communication January 22nd, 2018

Piecework at the nano assembly line: Electric fields drive nano-motors a 100,000 times faster than previous methods January 22nd, 2018

Thanks for the memory: NIST takes a deep look at memristors January 20th, 2018

Arrowhead Pharmaceuticals Announces Pricing of Underwritten Public Offering of Common Stock January 18th, 2018

Govt.-Legislation/Regulation/Funding/Policy

Researchers use sound waves to advance optical communication January 22nd, 2018

Piecework at the nano assembly line: Electric fields drive nano-motors a 100,000 times faster than previous methods January 22nd, 2018

Thanks for the memory: NIST takes a deep look at memristors January 20th, 2018

New Method Uses DNA, Nanoparticles and Top-Down Lithography to Make Optically Active Structures: Technique could lead to new classes of materials that can bend light, such as for those used in cloaking devices January 18th, 2018

Chip Technology

Researchers use sound waves to advance optical communication January 22nd, 2018

Thanks for the memory: NIST takes a deep look at memristors January 20th, 2018

Leti to Demo New Curving Technology at Photonics West that Improves Performance of Optical Components January 18th, 2018

Ultra-thin memory storage device paves way for more powerful computing January 17th, 2018

Nanotubes/Buckyballs/Fullerenes/Nanorods

Nanotube fibers in a jiffy: Rice University lab makes short nanotube samples by hand to dramatically cut production time January 11th, 2018

Touchy nanotubes work better when clean: Rice, Swansea scientists show that decontaminating nanotubes can simplify nanoscale devices January 4th, 2018

Paving the way for a non-electric battery to store solar energy: UMass Amherst scientists say a polymer chain organized like a string of Christmas lights assists energy storage December 22nd, 2017

Nanotubes go with the flow to penetrate brain tissue: Rice University scientists, engineers develop microfluidic devices, microelectrodes for gentle implantation December 19th, 2017

Nanoelectronics

Viewing atomic structures of dopant atoms in 3-D relating to electrical activity in a semiconductor December 28th, 2017

Electronically-smooth '3-D graphene': A bright future for trisodium bismuthide: Electronically-smooth nature of trisodium bismuthide makes it a viable alternative to graphene/h-BN December 22nd, 2017

Columbia engineers create artificial graphene in a nanofabricated semiconductor structure: Researchers are the first to observe the electronic structure of graphene in an engineered semiconductor; finding could lead to progress in advanced optoelectronics and data processing December 13th, 2017

GLOBALFOUNDRIES, Fudan Team to Deliver Next Generation Dual Interface Smart Card November 14th, 2017

Discoveries

Researchers use sound waves to advance optical communication January 22nd, 2018

Piecework at the nano assembly line: Electric fields drive nano-motors a 100,000 times faster than previous methods January 22nd, 2018

Thanks for the memory: NIST takes a deep look at memristors January 20th, 2018

New Method Uses DNA, Nanoparticles and Top-Down Lithography to Make Optically Active Structures: Technique could lead to new classes of materials that can bend light, such as for those used in cloaking devices January 18th, 2018

Announcements

Researchers use sound waves to advance optical communication January 22nd, 2018

Piecework at the nano assembly line: Electric fields drive nano-motors a 100,000 times faster than previous methods January 22nd, 2018

Thanks for the memory: NIST takes a deep look at memristors January 20th, 2018

Arrowhead Pharmaceuticals Announces Pricing of Underwritten Public Offering of Common Stock January 18th, 2018

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