Featured Research

from universities, journals, and other organizations

Graphene's varying conductivity levels pinpointed

Date:
May 3, 2011
Source:
North Carolina State University
Summary:
Graphene is often touted as the latest "wonder material," and may be the electronics industry's next great hope for the creation of extremely fast electronic devices. Researchers have found one of the first roadblocks to utilizing graphene by proving that its conductivity decreases significantly when more than one layer is present.

Graphene is often touted as the latest "wonder material," and may be the electronics industry's next great hope for the creation of extremely fast electronic devices. Researchers at North Carolina State University have found one of the first roadblocks to utilizing graphene by proving that its conductivity decreases significantly when more than one layer is present.

Related Articles


Graphene's structure is what makes it promising for electronics. Because of the way its carbon atoms are arranged, its electrons are very mobile. Mobile electrons mean that a material should have high conductivity. But NC State physicist Dr. Marco Buongiorno-Nardelli and NC State electrical and computer engineer Dr. Ki Wook Kim wanted to find a way to study the behavior of "real" graphene and see if this was actually the case.

"You can talk about the electronic structure of graphene, but you must consider that those electrons don't exist alone in the material," Buongiorno-Nardelli says. "There are impurities, and most importantly, there are vibrations present from the atoms in the material. The electrons encounter and interact with these vibrations, and that can affect the material's conductivity."

Buongiorno-Nardelli, Kim and graduate students Kostya Borysenko and Jeff Mullen developed a computer model that would predict the actual conductivity of graphene, both as a single layer and in a bilayer form, with two layers of graphene sitting on top of one another. It was important to study the bilayer model because actual electronic devices cannot work with only a single layer of the material present.

"You cannot make a semiconductor with just one graphite layer," Buongiorno-Nardelli explains. "To make a device, the conductive material must have a means by which it can be turned off and on. And bilayer provides such ability."

With the help of the high performance computers at Oak Ridge National Laboratories, the NC State team discovered both good and bad news about graphene. Their results appear as an Editor's Suggestion in the April 15 edition of Physical Review B.

With a single layer of graphene, the mobility -- and therefore conductivity -- shown by the researchers' simulations turned out to be much higher than they had originally thought. This good news was balanced, however, by the results from the bilayer state.

"We expected that the electrons' conductivity in bilayer graphene could be somewhat worse, due to the ways in which the vibrations from the atoms in each individual layer interact with one another," Mullen says. "Surprisingly, we found that the mobility of electrons in bilayer graphene is roughly an order of magnitude lower than in a single graphene sheet."

"The reduction is substantial, but even this reduced number is higher than in many conventional semiconductors," Borysenko adds.

Buongiorno-Nardelli says that the NC State researchers are turning their attention to remedying this problem.

"If we put the graphene on a substrate that can 'siphon off' some of the heat generated by the electric current, the crystal vibrations will decrease and the mobility will increase. Those are our next steps -- running the simulations with graphene and substrates that have this property."

The research was funded by the U.S. Department of Energy and the DARPA-CERA program.


Story Source:

The above story is based on materials provided by North Carolina State University. Note: Materials may be edited for content and length.


Journal Reference:

  1. K. Borysenko, J. Mullen, X. Li, Y. Semenov, J. Zavada, M. Nardelli, K. Kim. Electron-phonon interactions in bilayer graphene. Physical Review B, 2011; 83 (16) DOI: 10.1103/PhysRevB.83.161402

Cite This Page:

North Carolina State University. "Graphene's varying conductivity levels pinpointed." ScienceDaily. ScienceDaily, 3 May 2011. <www.sciencedaily.com/releases/2011/04/110418114206.htm>.
North Carolina State University. (2011, May 3). Graphene's varying conductivity levels pinpointed. ScienceDaily. Retrieved November 28, 2014 from www.sciencedaily.com/releases/2011/04/110418114206.htm
North Carolina State University. "Graphene's varying conductivity levels pinpointed." ScienceDaily. www.sciencedaily.com/releases/2011/04/110418114206.htm (accessed November 28, 2014).

Share This


More From ScienceDaily



More Matter & Energy News

Friday, November 28, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

NASA's First 3-D Printer In Space Creates Its First Object

NASA's First 3-D Printer In Space Creates Its First Object

Newsy (Nov. 26, 2014) The International Space Station is now using a proof-of-concept 3D printer to test additive printing in a weightless, isolated environment. Video provided by Newsy
Powered by NewsLook.com
Bolivian Recycling Initiative Turns Plastic Waste Into School Furniture

Bolivian Recycling Initiative Turns Plastic Waste Into School Furniture

Reuters - Innovations Video Online (Nov. 26, 2014) Innovative recycling project in La Paz separates city waste and converts plastic garbage into school furniture made from 'plastiwood'. Tara Cleary reports. Video provided by Reuters
Powered by NewsLook.com
Blu-Ray Discs Getting Second Run As Solar Panels

Blu-Ray Discs Getting Second Run As Solar Panels

Newsy (Nov. 26, 2014) Researchers at Northwestern University are repurposing Blu-ray movies for better solar panel technology thanks to the discs' internal structures. Video provided by Newsy
Powered by NewsLook.com
Today's Prostheses Are More Capable Than Ever

Today's Prostheses Are More Capable Than Ever

Newsy (Nov. 26, 2014) Advances in prosthetics are making replacement body parts stronger and more lifelike than they’ve ever been. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins