Oct 16, 2010 07:46 GMT  ·  By
This image of a single suspended sheet of graphene shows individual carbon atoms (yellow) on the honeycomb lattice
   This image of a single suspended sheet of graphene shows individual carbon atoms (yellow) on the honeycomb lattice

A group of investigators from the United States announces that new data have been collected on how a phenomenon known as noise develops in the carbon compound graphene.

The material, which is heralded as one of the most significant discoveries of the 21st century, will soon be used on a wide scale in numerous electronic applications.

It could be used to produce logic switching devices, such as the ones that make today's circuit possible, but with increased performances. The Royal Swedish Academy of Sciences acknowledged this potential with a Nobel Prize in Physics this year.

One of the main traits of graphene is its 2D nature, which means that electrons which are confined within can only race across a plain surface. Nanoribbons can therefore be easily produced using it.

In a new series of investigations, researchers from the US Department of Energy's (DOE) Lawrence Berkeley National Laboratory (Berkeley Lab) looked at how noise develops in, and affects, graphene nanoribbons.

In charge of the research was Berkeley Labs materials scientist Yuegang Zhang, who collaborated with University of California in Los Angeles (UCLA) experts for this job.

“Atomically-thin graphene nanoribbons have provided an excellent platform for us to reveal the strong correlation between conductance fluctuation and the quantized electronic structures of quasi-one-dimensional systems,” Zhang says.

“This method should have much broader use to understand quantum transport phenomena in other nanoelectronic or molecular devices,” adds the scientist, who is based at the Berkeley Lab Molecular Foundry Inorganic Nanostructures Facility.

In the past, Zhang's group has been involved in developing new ways of producing graphene films, as well as in determining the low-frequency signal-to-noise ratios in graphene devices on silica substrates.

In the new study, the team looked at conductance fluctuation in nanoribbons, thus measuring the effect of quantum confinement in such structures.

“It amazes us to observe such a clear correlation between the noise and the band structure of these graphene nanomaterials,” says UCLA physicist and lead study author Guangyu Xu.

“This work adds strong support to the quasi-one-dimensional subband formation in graphene nanoribbons, in which our method turns out to be much more robust than conductance measurement,” he adds.

Details of the study appear in a paper called “Enhanced conductance fluctuation by quantum confinement effect in graphene nanoribbons,” which was published in the latest online issue of the esteemed scientific journal Nano Letters.