Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Graphene: What can go wrong? new studies point to wrinkles, process contaminants

08.07.2011
Using a combination of sophisticated computer modeling and advanced materials analysis techniques at synchrotron laboratories, a research team led by the University at Buffalo (UB) and including the National Institute of Standards and Technology (NIST), the Molecular Foundry at Lawrence Berkeley National Laboratory and SEMATECH* has demonstrated how some relatively simple processing flaws can seriously degrade the otherwise near-magical electronic properties of graphene.

Their new paper** demonstrates how both wrinkles in the graphene sheet and/or chance contaminants from processing—possibly hiding in those folds—disrupt and slow electron flow across the sheet. The results could be important for the design of commercial manufacturing processes that exploit the unique electrical properties of graphene. In the case of contaminant molecules at least, the paper also suggests that heating the graphene may be a simple solution.

Graphene, a nanostructured material that is essentially a one-atom thick sheet of carbon atoms arranged in a hexagonal pattern, is under intense study because of a combination of outstanding properties. It's extremely strong, conducts heat very well, and has high electrical conductivity while being flexible and transparent. Graphene's electrical properties, however, apparently depend a lot on flatness and purity.

Using X-rays, the UB team produced images that show the electron "cloud" lining the surface of graphene samples—the structure responsible for the high-speed transit of electrons across the sheet—and how wrinkles in the sheet distort the cloud and create bottlenecks. Spectrographic data showed anomalous "peaks" in some regions that also corresponded to distortions of the cloud. NIST researchers, using their dedicated materials science "beam line" at the National Synchrotron Light Source (NSLS),*** contributed a sensitive analysis of spectroscopic data confirming that these peaks were caused by chemical contaminants that adhered to the graphene during processing.

Significantly, the NIST synchrotron methods group was able to make detailed spectroscopic measurements of the graphene samples while heating them, and found that the mysterious peaks disappeared by the time the sample reached 150 degrees Celsius. This, according to Dan Fischer, leader of the NIST group, showed both that those particular disturbances in the electron cloud were due to contaminants, and that there is a way to get rid of them. "They're not chemical bound, they're just physically absorbed on the surface, and that's an important thing. You have a prescription for getting rid of them," Fischer said.

"When graphene was discovered, people were just so excited that it was such a good material that people really wanted to go with it and run as fast as possible," said Brian Schultz, one of three UB graduate students who were lead authors on the paper, "but what we're showing is that you really have to do some fundamental research before you understand how to process it and how to get it into electronics."

"This is the practical side of using graphene," agrees Fischer, "It has all these remarkable properties, but when you go to actually try to make something, maybe they stop working, and the question is: why and what do you do about it? These kinds of extremely sensitive, specialized techniques are part of that answer."

For more on the study, see the UB June 28, 2011, news announcement "Researchers Image Electron Clouds on the Surface of Graphene, Revealing How Folds in the Remarkable Material Can Harm Conductivity" at www.buffalo.edu/news/12673.

* SEMATECH is a nonprofit research consortium that advances the U.S. semiconductor industry.

** B.J. Schultz, C. J. Patridge, V. Lee, C. Jaye, P.S. Lysaght, C. Smith, J. Barnett, D.A. Fischer, D. Prendergast and S. Banerjee. Imaging local electronic corrugations and doped regions in graphene. Nature Communications. V2, 372. Published on-line June 28, 2011. doi:10.1038/ncomms1376.

*** The NSLS is located at the Brookhaven National Laboratory.

Michael Baum | EurekAlert!
Further information:
http://www.nist.gov

More articles from Materials Sciences:

nachricht An innovative high-performance material: biofibers made from green lacewing silk
20.01.2017 | Fraunhofer-Institut für Angewandte Polymerforschung IAP

nachricht Treated carbon pulls radioactive elements from water
20.01.2017 | Rice University

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Traffic jam in empty space

New success for Konstanz physicists in studying the quantum vacuum

An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Sustainable Water use in Agriculture in Eastern Europe and Central Asia

19.01.2017 | Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

 
Latest News

Helmholtz International Fellow Award for Sarah Amalia Teichmann

20.01.2017 | Awards Funding

An innovative high-performance material: biofibers made from green lacewing silk

20.01.2017 | Materials Sciences

Ion treatments for cardiac arrhythmia — Non-invasive alternative to catheter-based surgery

20.01.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>