Subscribe free to our newsletters via your
. 24/7 Space News .




CARBON WORLDS
Graphene grows better on certain copper crystals
by Liz Ahlberg, Physical Sciences Editor
Champaign IL (SPX) Nov 01, 2011


An illustration of rendered experimental data showing the polycrystalline copper surface and the differing graphene coverages. Graphene grows in a single layer on the (111) copper surface and in islands and multilayers elsewhere. Graphic by Joshua D. Wood.

New observations could improve industrial production of high-quality graphene, hastening the era of graphene-based consumer electronics, thanks to University of Illinois engineers.

By combining data from several imaging techniques, the team found that the quality of graphene depends on the crystal structure of the copper substrate it grows on. Led by electrical and computer engineering professors Joseph Lyding and Eric Pop, the researchers published their findings in the journal Nano Letters.

"Graphene is a very important material," Lyding said. "The future of electronics may depend on it. The quality of its production is one of the key unsolved problems in nanotechnology. This is a step in the direction of solving that problem."

To produce large sheets of graphene, methane gas is piped into a furnace containing a sheet of copper foil. When the methane strikes the copper, the carbon-hydrogen bonds crack. Hydrogen escapes as gas, while the carbon sticks to the copper surface.

The carbon atoms move around until they find each other and bond to make graphene. Copper is an appealing substrate because it is relatively cheap and promotes single-layer graphene growth, which is important for electronics applications.

"It's a very cost-effective, straightforward way to make graphene on a large scale," said Joshua Wood, a graduate student and the lead author of the paper.

"However, this does not take into consideration the subtleties of growing graphene," he said. "Understanding these subtleties is important for making high-quality, high-performance electronics."

While graphene grown on copper tends to be better than graphene grown on other substrates, it remains riddled with defects and multi-layer sections, precluding high-performance applications.

Researchers have speculated that the roughness of the copper surface may affect graphene growth, but the Illinois group found that the copper's crystal structure is more important.

Copper foils are a patchwork of different crystal structures. As the methane falls onto the foil surface, the shapes of the copper crystals it encounters affect how well the carbon atoms form graphene.

Different crystal shapes are assigned index numbers. Using several advanced imaging techniques, the Illinois team found that patches of copper with higher index numbers tend to have lower-quality graphene growth.

They also found that two common crystal structures, numbered (100) and (111), have the worst and the best growth, respectively. The (100) crystals have a cubic shape, with wide gaps between atoms. Meanwhile, (111) has a densely packed hexagonal structure.

"In the (100) configuration the carbon atoms are more likely to stick in the holes in the copper on the atomic level, and then they stack vertically rather than diffusing out and growing laterally," Wood said. "The (111) surface is hexagonal, and graphene is also hexagonal. It's not to say there's a perfect match, but that there's a preferred match between the surfaces."

Researchers now are faced with balancing the cost of all (111) copper and the value of high-quality, defect-free graphene. It is possible to produce single-crystal copper, but it is difficult and prohibitively expensive.

The U. of I. team speculates that it may be possible to improve copper foil manufacturing so that it has a higher percentage of (111) crystals. Graphene grown on such foil would not be ideal, but may be "good enough" for most applications.

"The question is, how do you optimize it while still maintaining cost effectiveness for technological applications?" said Pop, a co-author of the paper. "As a community, we're still writing the cookbook for graphene. We're constantly refining our techniques, trying out new recipes. As with any technology in its infancy, we are still exploring what works and what doesn't."

Next, the researchers hope to use their methodology to study the growth of other two-dimensional materials, including insulators to improve graphene device performance. They also plan to follow up on their observations by growing graphene on single-crystal copper.

"There's a lot of confusion in the graphene business right now," Lyding said. "The fact that there is a clear observational difference between these different growth indices helps steer the research and will probably lead to more quantitative experiments as well as better modeling. This paper is funneling things in that direction."

Lyding and Pop are affiliated with the Beckman Institute for Advanced Science and Technology at the U. of I. The Office of Naval Research, the Air Force Office of Scientific Research, and the Army Research Office supported this research.

.


Related Links
University of Illinois
Carbon Worlds - where graphite, diamond, amorphous, fullerenes meet






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News





CARBON WORLDS
New method of growing high-quality graphene promising for next-gen technology
Santa Barbara CA (SPX) Oct 26, 2011
Making waves as the material that will revolutionize electronics, graphene - composed of a single layer of Carbon atoms - has nonetheless been challenging to produce in a way that will be practical for innovative electronics applications. Researchers at UC Santa Barbara have discovered a method to synthesize high quality graphene in a controlled manner that may pave the way for next-generation e ... read more


CARBON WORLDS
Lunar Probe to search for water on Moon

Subtly Shaded Map of Moon Reveals Titanium Treasure Troves

NASA's Moon Twins Going Their Own Way

Titanium treasure found on Moon

CARBON WORLDS
Mars500 crew prepare to open the hatch

Opportunity Continues to Drive North

Opportunity Past 21 Miles of Driving! Will Spend Winter at Cape York

Scientists develope new way to determine when water was present on Mars and Earth

CARBON WORLDS
A global discussion: directions for space science research

NASA's NEEMO Mission Ending Early Due To Hurricane Rina

Explorer 1 The First US Explorer

NASA evacuates astronauts from deep-sea training

CARBON WORLDS
Aerospace officials confident in space docking despite degree of difficulty

China's first manual space docking hopefully 2012

China to conduct another manned space mission by 2012

China's satellite launch base upgraded ahead of Shenzhou-8 mission

CARBON WORLDS
Russian Progress space freighter undocks from ISS

Russia launches first supply ship for ISS after mishap

Russian space freighter leaves ISS

Station Crew Prepares For Progress Departure and New Arrivals

CARBON WORLDS
Vega getting ready for exploitation

MSU satellite orbits the Earth after early morning launch

NASA Launches Multi-Talented Earth-Observing Satellite

The Arianespace launcher family comes together in French Guiana

CARBON WORLDS
Three New Planets and a Mystery Object Discovered Outside Our Solar System

Dwarf planet sized up accurately as it blocks light of faint star

Herschel Finds Oceans of Water in Disk of Nearby Star

UH Astronomer Finds Planet in the Process of Forming

CARBON WORLDS
Radium likely cause of Tokyo hotspot: city office

High-quality white light produced by four-color laser source

No hands required as scientists achieve precise control of virtual flight

Google expands online bookstore to Canada




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement