Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > The Original Nano Workout: Helping Carbon Nanotubes Get Into Shape

Abstract:
Researchers at Rensselaer Polytechnic Institute have developed a new method of compacting carbon nanotubes into dense bundles. These tightly packed bundles are efficient conductors and could one day replace copper as the primary interconnects used on computer chips and even hasten the transition to next-generation 3-D stacked chips.

The Original Nano Workout: Helping Carbon Nanotubes Get Into Shape

Troy, NY | Posted on June 6th, 2007

Theoretical studies show that carbon nanotubes, if packed closely enough together, should be able to outperform copper as an electrical conductor. But because of the way carbon nanotubes are grown - in sparse nanoscale "forests" where carbon molecules compete for growth-inducing catalysts - scientists have been unable to successfully grow tightly packed bundles.

James Jiam-Qiang Lu, associate professor of physics and electrical engineering at Rensselaer, together with his research associate Zhengchun Liu, decided to investigate how to "densify" carbon nanotube bundles after they are already grown. He detailed the results of the post-growth densification project on June 6 at the Institute of Electrical and Electronics Engineers' International Interconnect Technology Conference (IITC) in Burlingame, Calif.

Lu's team discovered that by immersing vertically grown carbon nanotube bundles into a liquid organic solvent and allowing them to dry, the nanotubes pull close together into a dense bundle. Lu attributes the densification process to capillary coalescence, which is the same physical principle that allows moisture to move up a piece of tissue paper that is dipped into water.

The process boosts the density of these carbon nanotube bundles by five to 25 times. The higher the density, the better they can conduct electricity, Lu said. Several factors, including nanotube height, diameter, and spacing, affect the resulting density, Liu added. How the nanotubes are grown is also an important factor that impacts the resulting shape of the densified bundles.

Images of the experiment are more striking than any "before and after" photos of the latest fad diet. In one instance, Liu started with a carbon nanotube bundle 500 micrometers in diameter, shaped somewhat like a marshmallow, and dipped it into a bath of isopropyl alcohol. As the alcohol dried and evaporated, capillary forces drew the nanotubes closer together. Van Der Waals forces, the same molecular bonds that boost the adhesion of millions of setae on gecko toes and help the lizard defy gravity, ensure the nanotubes retain their tightly packed form.

The resulting bundle shrunk to a diameter of 100 micrometers, with a 25-fold increase in density. Instead of a marshmallow, it looked more like a carpenter's nail.

"It's a significant and critical step toward the realization of carbon nanotube interconnects with better performance than copper," Lu said of his research findings. "But there's still a lot of work to do before this technology can be integrated into industrial applications."

Despite his initial successes, Lu said the density results obtained are not ideal and carbon nanotubes would have to be further compacted before they can outperform copper as a conductor. A close-up photo, taken using a scanning electron microscope, reveals there are still large empty spaces between densified nanotubes. The research team is exploring various methods to achieve ever-higher density and higher quality of carbon nanotube bundles, he said.

Lu is confident that these densified carbon nanotubes, with their high conductivity, ability to carry high current density, and resistance to electromigration, will be key to the development of 3-D computer chips. Chips used today can only shrink so much smaller, as their flat surface must have enough room to accommodate scores of different components. But the semiconductor industry and academia are looking at ways to layer chip components into a vertical stack, which could dramatically shrink the size of the overall chip.

Densified carbon nanotubes, with their ends trimmed and polished, can be the basic building blocks for interconnects that would link the stacked layers of a 3-D computer chip, Lu said.

"Carbon nanotubes are one of the most promising materials for interconnects in 3-D integration," he said. Other potential applications of the densified nanotubes are high surface area electrodes for supercapacitors, fuel cell electrodes for hydrogen storage, heat dissipation materials for thermal conductors, and other situations that require high electrical, thermal, or mechanical performance.

Lu's group closely collaborates with a research group led by Pulickel Ajayan, the Henry Burlage Professor of Materials Science and Engineering at Rensselaer, who provided Lu with the grown nanotubes. Along with Liu, who leads the carbon nanotube densification process investigation, the research team includes research associates Navdeep Bajwa, Lijie Ci, Swastik Kar, and Sang Hwui Lee.

The team has filed a disclosure and is moving forward toward a patent for their densification process.

Lu's research is supported by Defense Advanced Research Projects Agency (DARPA), the Microelectronics Advanced Research Corporation (MARCO), and the New York State Office of Science, Technology and Academic Research (NYSTAR) through the Interconnect Focus Center (IFC). The IFC is a multi-university research center focusing on the discovery and invention of new solutions that will enable the U.S. semiconductor industry to transcend known limits on interconnects that would otherwise decelerate or halt the rate of progress toward future terascale system integration.

For more information on Lu's research into 3-D integration, go to:
http://www.rpi.edu/research/magazine/spring05/chips.html

####

About Rensselaer Polytechnic Institute
Rensselaer Polytechnic Institute, founded in 1824, is the nationís oldest technological university. The university offers bachelorís, masterís, and doctoral degrees in engineering, the sciences, information technology, architecture, management, and the humanities and social sciences. Institute programs serve undergraduates, graduate students, and working professionals around the world. Rensselaer faculty are known for pre-eminence in research conducted in a wide range of fields, with particular emphasis in biotechnology, nanotechnology, information technology, and the media arts and technology. The Institute is well known for its success in the transfer of technology from the laboratory to the marketplace so that new discoveries and inventions benefit human life, protect the environment, and strengthen economic development.

For more information, please click here

Contacts:
Michael Mullaney
Rensselaer Polytechnic Institute
Troy, NY
518.276.6161 (office)
518.698.6336 (cell)

Copyright © Rensselaer Polytechnic Institute

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

Chip Technology

Explaining how 2-D materials break at the atomic level January 20th, 2017

New research helps to meet the challenges of nanotechnology: Research helps to make the most of nanoscale catalytic effects for nanotechnology January 20th, 2017

Ultra-precise chip-scale sensor detects unprecedentedly small changes at the nanoscale January 20th, 2017

Nanometrics to Announce Fourth Quarter and Full Year Financial Results on February 7, 2017 January 19th, 2017

Nanotubes/Buckyballs/Fullerenes

Captured on video: DNA nanotubes build a bridge between 2 molecular posts: Research may lead to new lines of direct communication with cells January 9th, 2017

Nano-chimneys can cool circuits: Rice University scientists calculate tweaks to graphene would form phonon-friendly cones January 4th, 2017

WPI researchers build liquid biopsy chip that detects metastatic cancer cells in blood December 15th, 2016

Infrared instrumentation leader secures exclusive use of Vantablack coating December 5th, 2016

Discoveries

Traffic jam in empty space: New success for Konstanz physicists in studying the quantum vacuum January 22nd, 2017

A big nano boost for solar cells: Kyoto University and Osaka Gas effort doubles current efficiencies January 21st, 2017

Explaining how 2-D materials break at the atomic level January 20th, 2017

New research helps to meet the challenges of nanotechnology: Research helps to make the most of nanoscale catalytic effects for nanotechnology January 20th, 2017

Announcements

Traffic jam in empty space: New success for Konstanz physicists in studying the quantum vacuum January 22nd, 2017

A big nano boost for solar cells: Kyoto University and Osaka Gas effort doubles current efficiencies January 21st, 2017

A toolkit for transformable materials: How to design materials with reprogrammable shape and function January 20th, 2017

New research helps to meet the challenges of nanotechnology: Research helps to make the most of nanoscale catalytic effects for nanotechnology January 20th, 2017

Battery Technology/Capacitors/Generators/Piezoelectrics/Thermoelectrics/Energy storage

Chemists Cook up New Nanomaterial and Imaging Method: Nanomaterials can store all kinds of things, including energy, drugs and other cargo January 19th, 2017

Nanoscale view of energy storage January 16th, 2017

One step closer to reality: Devices that convert heat into electricity: Composite material yields 10 times -- or higher -- voltage output January 4th, 2017

STMicroelectronics Peps Up Booming Social-Fitness Scene with Smart Motion Sensors for Better Accuracy, Longer Battery Life, and Faster Time to Market January 2nd, 2017

Fuel Cells

Scientists boost catalytic activity for key chemical reaction in fuel cells: New platinum-based catalysts with tensile surface strain could improve fuel cell efficiency December 19th, 2016

It's basic: Alternative fuel cell technology reduces cost: Study sets performance targets for metal-free fuel cell membrane December 13th, 2016

Keeping electric car design on the right road: A closer look at the life-cycle impacts of lithium-ion batteries and proton exchange membrane fuel cells December 9th, 2016

Water vapor sets some oxides aflutter: Newly discovered phenomenon could affect materials in batteries and water-splitting devices October 3rd, 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