Nanotechnology Now

Our NanoNews Digest Sponsors


Heifer International

Wikipedia Affiliate Button

Home > Press > New theory explains electronic and thermal behavior of nanotubes

New theory explains electronic and thermal behavior of nanotubes

Champaign, IL | Posted on January 19, 2006

Researchers at the University of Illinois at Urbana-Champaign have made an important theoretical breakthrough in the understanding of energy dissipation and thermal breakdown in metallic carbon nanotubes. Their discovery will help move nanotube wires from laboratory to marketplace.

The remarkable electrical and mechanical properties of metallic carbon nanotubes make them promising candidates for interconnects in future nanoscale electronic devices. But, like tiny metal wires, nanotubes grow hotter as electrical current is increased. At some point, a nanotube will burn apart like an element in a blown fuse.

"Heat dissipation is a fundamental problem of electronic transport at the nanoscale," said Jean-Pierre Leburton, the Gregory Stillman Professor of Electrical and Computer Engineering at Illinois and co-author of a paper published in the Dec. 21 issue of the journal Physical Review Letters. "To fully utilize nanotubes as interconnects, we must characterize them and understand their behavior and operating limits."

Up to now, no coherent interpretation had been proposed that reconciled heat dissipation and electronic transport, and described thermal effects in metallic carbon nanotubes under electronic stress, said Leburton, who is also a researcher at the Beckman Institute for Advanced Science and Technology, at the Micro and Nanotechnology Laboratory and at the Frederick Seitz Materials Research Laboratory. "Our theoretical results not only reproduce experimental data for electronic transport, they also explain the odd behavior of thermal breakdown in these nanotubes."

For example, in both theory and experiment, the shorter the nanotube, the larger the current that can be carried before thermal breakdown occurs. Also, the longer the nanotube, the faster the rise in temperature as the threshold current for thermal heating is reduced.

In nanotubes, heat generated by electrical resistance creates atomic vibrations in the nanostructure, which causes more collisions with the charge carriers. The additional collisions generate more heat and more vibrations, followed by even more collisions in a vicious cycle that ends when the nanotube burns apart, breaking the circuit.

"Short nanotubes can carry more current before burning apart because they dissipate heat better than longer nanotubes," Leburton said. "Although the entire nanotube experiences resistance heating, the electrical contacts at each end act as heat sinks, which in short nanotubes are relatively close to one another, leading to efficient heat removal."

This phenomenon also explains why the highest temperature always occurs in the middle of the nanostructure, Leburton said, "which is the furthest point away from the two ends, and where burning occurs in longer nanotubes under electrical stress."

In another important finding, Leburton and his colleagues have revised the common belief that charge carriers go ballistic in short metallic nanotubes having high currents. Researchers had previously thought that charge carriers traveled from one terminal to the other like a rocket; that is, without experiencing collisions.

"We have shown that the high current level in short metallic nanotubes is not due to ballistic transport, but to reduced heating effects," Leburton said. "Owing to their large concentration, the charge carriers collide efficiently among themselves, which prevent them from going ballistic. Even in short nanostructures, the current level is determined by a balance between the attractive force of the external electric field and the frictional force caused by the nanotube thermal vibrations. The collisions among charge carriers help the energy transfer to the nanotubes which results in heat dissipation."

Co-authors of the paper are Leburton, electrical and computer engineering professor Andreas Cangellaris and graduate student Marcelo Kuroda.

The work was funded by the National Science Foundation and the Beckman Institute.

Editor's note: To reach Jean-Pierre Leburton, call 217-333-6813; jleburto@uiuc.edu

####
Contact:
James E. Kloeppel
Physical Sciences Editor
217-244-1073
kloeppel@uiuc.edu

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

Possible Futures

Attosecond physics: Mapping electromagnetic waveforms July 25th, 2016

Borrowing from pastry chefs, engineers create nanolayered composites: Method to stack hundreds of nanoscale layers could open new vistas in materials science July 25th, 2016

Integration of novel materials with silicon chips makes new 'smart' devices possible July 25th, 2016

Accurate design of large icosahedral protein nanocages pushes bioengineering boundaries: Scientists used computational methods to build ten large, two-component, co-assembling icosahedral protein complexes the size of small virus coats July 25th, 2016

Nanotubes/Buckyballs/Fullerenes

Easier, faster, cheaper: A full-filling approach to making nanotubes of consistent quality: Approach opens a straightforward route for engineering the properties of single-wall carbon nanotubes July 19th, 2016

Sensing trouble: A new way to detect hidden damage in bridges, roads: University of Delaware engineers devise new method for monitoring structural health July 8th, 2016

Wireless, wearable toxic-gas detector: Inexpensive sensors could be worn by soldiers to detect hazardous chemical agents July 4th, 2016

Nanotubes' 'stuffing' as is: A scientist from the Lomonosov Moscow State University studied the types of carbon nanotubes' 'stuffing' June 2nd, 2016

Nanoelectronics

Ultra-flat circuits will have unique properties: Rice University lab studies 2-D hybrids to see how they differ from common electronics July 25th, 2016

Borrowing from pastry chefs, engineers create nanolayered composites: Method to stack hundreds of nanoscale layers could open new vistas in materials science July 25th, 2016

Making magnets flip like cats at room temperature: Heusler alloy NiMnSb could prove valuable as a new material for digital information processing and storage July 25th, 2016

Quantum drag:University of Iowa physicist says current in one iron magnetic sheet can create quantized spin waves in another, separate sheet July 22nd, 2016

Discoveries

Attosecond physics: Mapping electromagnetic waveforms July 25th, 2016

Borrowing from pastry chefs, engineers create nanolayered composites: Method to stack hundreds of nanoscale layers could open new vistas in materials science July 25th, 2016

Integration of novel materials with silicon chips makes new 'smart' devices possible July 25th, 2016

Accurate design of large icosahedral protein nanocages pushes bioengineering boundaries: Scientists used computational methods to build ten large, two-component, co-assembling icosahedral protein complexes the size of small virus coats July 25th, 2016

Announcements

Borrowing from pastry chefs, engineers create nanolayered composites: Method to stack hundreds of nanoscale layers could open new vistas in materials science July 25th, 2016

Integration of novel materials with silicon chips makes new 'smart' devices possible July 25th, 2016

Accurate design of large icosahedral protein nanocages pushes bioengineering boundaries: Scientists used computational methods to build ten large, two-component, co-assembling icosahedral protein complexes the size of small virus coats July 25th, 2016

XEI Scientific Partners with Electron Microscopy Sciences to Promote and Sell its Products in North and South America July 25th, 2016

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