Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Speed bumps less important than potholes for graphene

16.07.2007
For electrical charges racing through an atom-thick sheet of graphene, occasional hills and valleys are no big deal, but the potholes—single-atom defects in the crystal—they’re killers.

That’s one of the conclusions reached by researchers from the National Institute of Standards and Technology (NIST) and the Georgia Institute of Technology who created detailed maps of electron interference patterns in graphene to understand how defects in the two-dimensional carbon crystal affect charge flow through the material. The results, appearing in the July 13 issue of Science*, have implications for the design of graphene-based nanoelectronics.

A single layer of carbon atoms tightly arranged in a honeycomb pattern, graphene was long thought to be an interesting theoretical concept that was impossible in practice—it would be too unstable, and crumple into some other configuration. The discovery, in 2004, that graphene actually could exist touched off a rush of experimentation to explore its properties. Graphene has been described as a carbon nanotube unrolled, and shares some of the unique properties of nanotubes. In particular, it’s a so-called ballistic conductor, meaning that electrons flow through it at high speed, like photons through a vacuum, with virtually no collisions with the atoms in the crystal. This makes it a potentially outstanding conductor for wires and other elements in nanoscale electronics.

Defects or irregularities in the graphene crystal, however, can cause the electrons to bounce back or scatter, the equivalent of electrical resistance, so one key issue is just what sort of defects cause scattering, and how much" To answer this, the NIST-Georgia Tech team grew layers of graphene on wafers of silicon carbide crystals and mapped the sheets with a custom-built scanning tunneling microscope (STM) in the NIST Center for Nanoscale Science and Technology that can measure both physical surface features and the interference patterns caused by electrons scattering in the crystal. (Graphene on silicon carbide is a leading candidate for graphene-based nanoelectronics.)

The results are counter-intuitive. Irregularities in the underlying silicon carbide cause bumps and dips in the graphene sheet that lies over it rather like a blanket on a lumpy bed, but these relatively large bumps have only a minor effect on the electron’s passage. In contrast, missing carbon atoms in the crystal lattice cause strong scattering, the interference patterns rippling around them like waves hitting the piles of a pier. From a detailed analysis of these interference patterns, the team verified that electrons in the graphene sheet behave like photons, even at the nanometer scale.

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

More articles from Physics and Astronomy:

nachricht Tune your radio: galaxies sing while forming stars
21.02.2017 | Max-Planck-Institut für Radioastronomie

nachricht Breakthrough with a chain of gold atoms
17.02.2017 | Universität Konstanz

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

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

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Impacts of mass coral die-off on Indian Ocean reefs revealed

21.02.2017 | Earth Sciences

Novel breast tomosynthesis technique reduces screening recall rate

21.02.2017 | Medical Engineering

Use your Voice – and Smart Homes will “LISTEN”

21.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>