Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Barrier to faster graphene devices identified and suppressed

14.03.2012
These days graphene is the rock star of materials science, but it has an Achilles heel: It is exceptionally sensitive to its electrical environment.

This single-atom-thick honeycomb of carbon atoms is lighter than aluminum, stronger than steel and conducts heat and electricity better than copper.

As a result, scientists around the world are trying to turn it into better computer displays, solar panels, touch screens, integrated circuits and biomedical sensors, among other possible applications. However, it has proven extremely difficult to reliably create graphene-based devices that live up to its electrical potential when operating at room temperature and pressure.

Now, writing in the Mar. 13 issue of the journal Nature Communications, a team of Vanderbilt physicists reports that they have nailed down the source of the interference inhibiting the rapid flow of electrons through graphene-based devices and found a way to suppress it. This allowed them to achieve record-levels of room-temperature electronmobility – the measure of the speed that electrons travel through a material – three times greater than those reported in previous graphene-based devices.

According to the experts, graphene may have the highest electron mobility of any known material. In practice, however, the measured levels of mobility, while significantly higher than in other materials like silicon, have been considerably below its potential.

“The problem is that, when you make graphene, you don’t get just graphene. You also get a lot of other stuff,” said Kirill Bolotin, assistant professor of physics, who conducted the study with Research Associate A.K.M. Newaz. “Graphene is extraordinarily susceptible to external influences so the electrical fields created by charged impurities on its surface scatter the electrons traveling through the graphene sheets, making graphene-based transistors operate slower and heat up more.”

A number of researchers had proposed that the charged impurities that are omnipresent on the surface of graphene were the main culprits, but it wasn’t completely certain. Also, several other theories had been advanced to explain the phenomenon.

“Our study shows without question that the charged crap is the problem and, if you want to make better graphene devices, it is the enemy that you need to fight,” Bolotin said.

At the same time, the experiment didn’t find evidence supporting one of the alternative theories, that ripples in the graphene sheets were a significant source of electron scattering.

In order to get a handle on the mobility problem, Bolotin’s team suspended sheets of graphene in a series of different liquids and measured the material’s electric transport properties. They found that graphene’s electron mobility is dramatically increased when graphene is submerged in electrically neutral liquids that can absorb large amounts of electrical energy (have large dielectric constants). They achieved the record-level mobility of 60,000 using anisole, a colorless liquid with a pleasant, aromatic odor used chiefly in perfumery.

“These liquids suppress the electrical fields from the impurities, allowing the electrons to flow with fewer obstructions,” Bolotin said.

Now that the source of the degradation in electrical performance of graphene has been clearly identified, it should be possible to come up with reliable device designs, Bolotin said.

According to the physicist, there is also a potential advantage to graphene’s extraordinary sensitivity to its environment that can be exploited. It should make extremely sensitive sensors of various types and, because it is made entirely of carbon, it is biocompatible and so should be ideal for biological sensors.

University Distinguished Professor of Physics & Engineering Sokrates Pantelides and Research Associates Yevgeniy Puzyrev and Bin Wang contributed to the study.
The research was funded by an award from the National Science Foundation.
Visit Research News @ Vanderbilt for more research news from Vanderbilt.

David F. Salisbury | Vanderbilt University
Further information:
http://www.vanderbilt.edu

More articles from Materials Sciences:

nachricht In borophene, boundaries are no barrier
17.07.2018 | Rice University

nachricht Research finds new molecular structures in boron-based nanoclusters
13.07.2018 | Brown 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: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Microscopic trampoline may help create networks of quantum computers

17.07.2018 | Information Technology

In borophene, boundaries are no barrier

17.07.2018 | Materials Sciences

The role of Sodium for the Enhancement of Solar Cells

17.07.2018 | Power and Electrical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>