Nanotechnology Now

Our NanoNews Digest Sponsors


Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > With 'ribbons' of graphene, width matters: A narrow enough ribbon will transform a high-performance conductor into a semiconductor

Yaoyi Li (foreground) and Mingxing Chen, UWM physics postdoctoral researchers, display an image of a ribbon of graphene 1 nanometer wide. In the image, achieved with a scanning-tunneling microscope, atoms are visible as "bumps."

Credit: Troye Fox, UWM Photo Services
Yaoyi Li (foreground) and Mingxing Chen, UWM physics postdoctoral researchers, display an image of a ribbon of graphene 1 nanometer wide. In the image, achieved with a scanning-tunneling microscope, atoms are visible as "bumps."

Credit: Troye Fox, UWM Photo Services

Abstract:
Using graphene ribbons of unimaginably small widths - just several atoms across - a group of researchers at the University of Wisconsin-Milwaukee (UWM) has found a novel way to "tune" the wonder material, causing the extremely efficient conductor of electricity to act as a semiconductor.

With 'ribbons' of graphene, width matters: A narrow enough ribbon will transform a high-performance conductor into a semiconductor

Milwaukee, WI | Posted on July 4th, 2014

In principle, their method for producing these narrow ribbons - at a width roughly equal to the diameter of a strand of human DNA - and manipulating the ribbons' electrical conductivity could be used to produce nano-devices.

Graphene, a one-atom-thick sheet of carbon atoms, is touted for its high potential to yield devices at nanoscale and deliver computing at quantum speed. But before it can be applied to nanotechnology, researchers must first find an easy method of controlling the flow of electrons in order to devise even a simple on-off switch.

"Nano-ribbons are model systems for studying nanoscale effects in graphene, but obtaining a ribbon width below 10 nanometers and characterizing its electronic state is quite challenging," says Yaoyi Li, a UWM physics postdoctoral researcher and first author of a paper published July 2 in the journal Nature Communications.

By imaging the ribbons with scanning-tunneling microscopy, researchers have confirmed how narrow the ribbon width must be to alter graphene's electrical properties, making it more tunable.

"We found the transition happens at three nanometers and the changes are abrupt," says Michael Weinert, a UWM theoretical physicist who worked on the Department of Energy-supported project with experimental physicist Lian Li. "Before this study, there was no experimental evidence of what width the onset of these behaviors is."

The team also found that the narrower the ribbon becomes, the more "tunable" the material's behaviors. The two edges of such a narrow ribbon are able to strongly interact, essentially transforming the ribbon into a semiconductor with tunable qualities similar to that of silicon.

The first hurdle

Current methods of cutting can produce ribbon widths of five nanometers across, still too wide to achieve the tunable state, says Yaoyi Li. In addition to producing narrower ribbons, any new strategy for cutting they devised would also have to result in a straight alignment of the atoms at the ribbon edges in order to maintain the electrical properties, he adds.

So the UWM team used iron nanoparticles on top of the graphene in a hydrogen environment. Iron is a catalyst that causes hydrogen and carbon atoms to react, creating a gas that etches a trench into the graphene. The cutting is accomplished by precisely controlling the hydrogen pressure, says Lian Li.

The iron nanoparticle moves randomly across the graphene, producing ribbons of various widths - including some as thin as one nanometer, he says. The method also produces edges with properly aligned atoms.

One limitation exists for the team's cutting method, and that has to do with where the edges are cut. The atoms in graphene are arranged on a honeycomb lattice that, depending on the direction of the cut produces either an "armchair-shaped" edge or a "zigzag" one. The semiconducting behaviors the researchers observed with their etching method will only occur with a cut in the zigzag configuration.

Manipulating for function

When cut, the carbon atoms at the edges of the resulting ribbons have only two of the normal three neighbors, creating a kind of bond that attracts hydrogen atoms and corrals electrons to the edges of the ribbon. If the ribbon is narrow enough, the electrons on opposite sides can still interact, creating a semiconductive electrical behavior, says Weinert.

The researchers are now experimenting with saturating the edges with oxygen, rather than hydrogen, to investigate whether this changes the electrical behavior of the graphene to that of a metal.

Adding function to graphene nano-ribbons through this process could make possible the sought-after goal of atomic-scale components made of the same material, but with different electrical behaviors, says Weinert.

####

For more information, please click here

Contacts:
Lian Li

414-229-5108

Copyright © University of Wisconsin - Milwaukee

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Revealing the nature of magnetic interactions in manganese oxide: New technique for probing local magnetic interactions confirms 'superexchange' model that explains how the material gets its long-range magnetic order May 25th, 2016

Gigantic ultrafast spin currents: Scientists from TU Wien (Vienna) are proposing a new method for creating extremely strong spin currents. They are essential for spintronics, a technology that could replace today's electronics May 25th, 2016

Diamonds closer to becoming ideal semiconductors: Researchers find new method for doping single crystals of diamond May 25th, 2016

Supercrystals with new architecture can enhance drug synthesis May 24th, 2016

Graphene/ Graphite

Rice de-icer gains anti-icing properties: Dual-function, graphene-based material good for aircraft, extreme environments May 23rd, 2016

Graphene makes rubber more rubbery May 23rd, 2016

Graphene: Progress, not quantum leaps May 23rd, 2016

Researchers demonstrate size quantization of Dirac fermions in graphene: Characterization of high-quality material reveals important details relevant to next generation nanoelectronic devices May 20th, 2016

Molecular Nanotechnology

Little ANTs: Researchers build the world's tiniest engine May 3rd, 2016

Researchers create artificial protein to control assembly of buckyballs April 27th, 2016

Physicists build engine consisting of one atom: World's smallest heat engine uses just a single particle April 17th, 2016

Physicists prove energy input predicts molecular behavior: Theoretical proof could lead to more reliable nanomachines March 22nd, 2016

Chip Technology

Gigantic ultrafast spin currents: Scientists from TU Wien (Vienna) are proposing a new method for creating extremely strong spin currents. They are essential for spintronics, a technology that could replace today's electronics May 25th, 2016

Diamonds closer to becoming ideal semiconductors: Researchers find new method for doping single crystals of diamond May 25th, 2016

Dartmouth team creates new method to control quantum systems May 24th, 2016

Attosecond physics: A switch for light-wave electronics May 24th, 2016

Nanoelectronics

Researchers demonstrate size quantization of Dirac fermions in graphene: Characterization of high-quality material reveals important details relevant to next generation nanoelectronic devices May 20th, 2016

Graphene: A quantum of current - When current comes in discrete packages: Viennese scientists unravel the quantum properties of the carbon material graphene May 20th, 2016

New type of graphene-based transistor will increase the clock speed of processors: Scientists have developed a new type of graphene-based transistor and using modeling they have demonstrated that it has ultralow power consumption compared with other similar transistor devices May 19th, 2016

Self-healing, flexible electronic material restores functions after many breaks May 17th, 2016

Discoveries

Revealing the nature of magnetic interactions in manganese oxide: New technique for probing local magnetic interactions confirms 'superexchange' model that explains how the material gets its long-range magnetic order May 25th, 2016

Gigantic ultrafast spin currents: Scientists from TU Wien (Vienna) are proposing a new method for creating extremely strong spin currents. They are essential for spintronics, a technology that could replace today's electronics May 25th, 2016

Diamonds closer to becoming ideal semiconductors: Researchers find new method for doping single crystals of diamond May 25th, 2016

Supercrystals with new architecture can enhance drug synthesis May 24th, 2016

Announcements

Revealing the nature of magnetic interactions in manganese oxide: New technique for probing local magnetic interactions confirms 'superexchange' model that explains how the material gets its long-range magnetic order May 25th, 2016

Gigantic ultrafast spin currents: Scientists from TU Wien (Vienna) are proposing a new method for creating extremely strong spin currents. They are essential for spintronics, a technology that could replace today's electronics May 25th, 2016

Diamonds closer to becoming ideal semiconductors: Researchers find new method for doping single crystals of diamond May 25th, 2016

Supercrystals with new architecture can enhance drug synthesis May 24th, 2016

Interviews/Book Reviews/Essays/Reports/Podcasts/Journals/White papers

Revealing the nature of magnetic interactions in manganese oxide: New technique for probing local magnetic interactions confirms 'superexchange' model that explains how the material gets its long-range magnetic order May 25th, 2016

Gigantic ultrafast spin currents: Scientists from TU Wien (Vienna) are proposing a new method for creating extremely strong spin currents. They are essential for spintronics, a technology that could replace today's electronics May 25th, 2016

Diamonds closer to becoming ideal semiconductors: Researchers find new method for doping single crystals of diamond May 25th, 2016

Supercrystals with new architecture can enhance drug synthesis May 24th, 2016

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







Car Brands
Buy website traffic