Nanotechnology Now

Our NanoNews Digest Sponsors





Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > Playing pool with carbon atoms: UA physicists discover how to change the crystal structure of graphene

Using a sharp metal scanning tunneling microscopy tip, LeRoy and his collaborators were able to move the domain border between the two graphene configurations around.

Credit: Pablo San-Jose ICMM-CSI
Using a sharp metal scanning tunneling microscopy tip, LeRoy and his collaborators were able to move the domain border between the two graphene configurations around.

Credit: Pablo San-Jose ICMM-CSI

Abstract:
A University of Arizona-led team of physicists has discovered how to change the crystal structure of graphene, more commonly known as pencil lead, with an electric field, an important step toward the possible use of graphene in microprocessors that would be smaller and faster than current, silicon-based technology.

Playing pool with carbon atoms: UA physicists discover how to change the crystal structure of graphene

Tucson, AZ | Posted on April 30th, 2014

Graphene consists of extremely thin sheets of graphite: when writing with a pencil, graphene sheets slough off the pencil's graphite core and stick to the page. If placed under a high-powered electron microscope, graphene reveals its sheet-like structure of cross-linked carbon atoms, resembling chicken wire.

When manipulated by an electric field, parts of the material are transformed from behaving as a metal to behaving as a semiconductor, the UA physicists found.

Graphene is the world's thinnest material, with 300,000 sheets needed to amount to the thickness of a human hair or a sheet of paper. Scientists and engineers are interested in it because of its possible applications in microelectronic devices, in hopes of propelling us from the silicon age to the graphene age. The tricky part is to control the flow of electrons through the material, a necessary prerequisite for putting it to work in any type of electronic circuit.

Brian LeRoy, UA associate professor of physics, and his collaborators have cleared a hurdle toward that goal by showing that an electric field is capable of controlling the crystal structure of trilayer graphene - which is made up of three layers of graphene.

Most materials require high temperatures, pressure or both to change their crystal structure, which is the reason why graphite doesn't spontaneously turn into diamond or vice versa.

"It is extremely rare for a material to change its crystal structure just by applying an electric field," LeRoy said. "Making trilayer graphene is an exceptionally unique system that could be utilized to create novel devices."

Trilayer graphene can be stacked in two unique ways. This is analogous to stacking layers of billiards balls in a triangular lattice, with the balls representing the carbon atoms.

"When you stack two layers of billiards balls, their 'crystal structure' is fixed because the top layer of balls must sit in holes formed by the triangles of the bottom layer," explained Matthew Yankowitz, a third-year doctoral student in LeRoy's lab. He is the first author on the published research, which appears in the journal Nature Materials. "The third layer of balls may be stacked in such a way that its balls are flush above the balls in the bottom layer, or it may be offset slightly so its balls come to lie above the holes formed by triangles in the bottom layer."

These two stacking configurations can naturally exist in the same flake of graphene. The two domains are separated by a sharp boundary where the carbon hexagons are strained to accommodate the transition from one stacking pattern to the other.

"Due to the different stacking configurations on either side of the domain wall, one side of the material behaves as a metal, while the other side behaves as a semiconductor," LeRoy explained.

While probing the domain wall with an electric field, applied by an extremely sharp metal scanning tunneling microscopy tip, the researchers in LeRoy's group discovered that they could move the position of the domain wall within the flake of graphene. And as they moved the domain wall, the crystal structure of the trilayer graphene changed in its wake.

"We had the idea that there would be interesting electronic effects at the boundary, and the boundary kept moving around on us," LeRoy said. "At first it was frustrating, but once we realized what was going on, it turned out to be the most interesting effect."

By applying an electric field to move the boundary, it is now possible for the first time to change the crystal structure of graphene in a controlled fashion.

"Now we have a knob that we can turn to change the material from metallic into semiconducting and vice versa to control the flow of electrons," LeRoy said. "It basically gives us an on-off switch, which had not been realized yet in graphene."

While more research is needed before graphene can be applied in technological applications on an industrial scale, researchers see ways it may be used.

"If you used a wide electrode instead of a pointed tip, you could move the boundary between the two configurations a farther distance, which could make it possible to create transistors from graphene," Yankowitz said.

Transistors are a staple of electronic circuits because they control the flow of electrons.

Unlike silicon transistors used now, graphene-based transistors could be extremely thin, making the device much smaller, and since electrons move through graphene much faster than through silicon, the devices would enable faster computing.

In addition, silicon-based transistors are being manufactured to function as one of two types - p-type or n-type - whereas graphene could operate as both. This would make them cheaper to produce and more versatile in their applications.

###

The other contributors to the research paper, "Electric field control of soliton motion and stacking in trilayer graphene," include Joel I-Jan Wang (Massachusetts Institute of Technology and Harvard University in Cambridge, Massachusetts), A. Glen Birdwell (U.S. Army Research Laboratory, Adelphi, Maryland), Yu-An Chen (MIT), K. Watanabe and T. Taniguchi (National Institute for Materials Science, Tsukuba, Japan), Philippe Jacquod (UA Department of Physics), Pablo San-Jose (Instituto de Ciencia de Materiales de Madrid) and Pablo Jarillo-Herrero (MIT).

####

For more information, please click here

Contacts:
Daniel Stolte

520-626-4402

Copyright © University of Arizona

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 Links

The study appears in the advance online publication of Nature Materials at:

Related News Press

News and information

The International Space Elevator Consortium (ISEC) is proud to announce the 2014 Space Elevator Conference! This annual event will be held at the Museum of Flight in Seattle, Washington from Friday, August 22nd through Sunday, August 24th August 19th, 2014

KaSAM-2014 International Conference (September 7-10, 2014, Kathmandu, Nepal) August 19th, 2014

Success in Intracellular Imaging of Cesium Distribution in Plants Used for Cesium Absorption August 19th, 2014

Electrical engineers take major step toward photonic circuits: Team invents non-metallic metamaterial that enables them to 'compress' and contain light August 19th, 2014

Graphene rubber bands could stretch limits of current healthcare, new research finds August 19th, 2014

Graphene

Graphene rubber bands could stretch limits of current healthcare, new research finds August 19th, 2014

New test reveals purity of graphene: Rice, Osaka scientists use terahertz waves to spot contaminants August 13th, 2014

Could hemp nanosheets topple graphene for making the ideal supercapacitor? August 12th, 2014

NANOPARTICLES INDIA August 8th, 2014

Laboratories

Promising Ferroelectric Materials Suffer From Unexpected Electric Polarizations: Brookhaven Lab scientists find surprising locked charge polarizations that impede performance in next-gen materials that could otherwise revolutionize data-driven devices August 18th, 2014

Govt.-Legislation/Regulation/Funding/Policy

Success in Intracellular Imaging of Cesium Distribution in Plants Used for Cesium Absorption August 19th, 2014

Electrical engineers take major step toward photonic circuits: Team invents non-metallic metamaterial that enables them to 'compress' and contain light August 19th, 2014

Promising Ferroelectric Materials Suffer From Unexpected Electric Polarizations: Brookhaven Lab scientists find surprising locked charge polarizations that impede performance in next-gen materials that could otherwise revolutionize data-driven devices August 18th, 2014

Novel chip-based platform could simplify measurements of single molecules: A nanopore-gated optofluidic chip combines electrical and optical measurements of single molecules onto a single platform August 14th, 2014

Chip Technology

Electrical engineers take major step toward photonic circuits: Team invents non-metallic metamaterial that enables them to 'compress' and contain light August 19th, 2014

Promising Ferroelectric Materials Suffer From Unexpected Electric Polarizations: Brookhaven Lab scientists find surprising locked charge polarizations that impede performance in next-gen materials that could otherwise revolutionize data-driven devices August 18th, 2014

AI Technology (AIT) Introduces Novel High Temperature Large Area Underfill with Proven Stress Absorption August 15th, 2014

Iranian Scientists Stabilize Protein on Highly Stable Electrode Surface August 14th, 2014

Discoveries

Success in Intracellular Imaging of Cesium Distribution in Plants Used for Cesium Absorption August 19th, 2014

Сalculations with Nanoscale Smart Particles August 19th, 2014

Electrical engineers take major step toward photonic circuits: Team invents non-metallic metamaterial that enables them to 'compress' and contain light August 19th, 2014

Graphene rubber bands could stretch limits of current healthcare, new research finds August 19th, 2014

Announcements

Сalculations with Nanoscale Smart Particles August 19th, 2014

Life on Mars? Implications of a newly discovered mineral-rich structure August 19th, 2014

Harris & Harris Group Letter to Shareholders on Website August 19th, 2014

Electrical engineers take major step toward photonic circuits: Team invents non-metallic metamaterial that enables them to 'compress' and contain light August 19th, 2014

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

Success in Intracellular Imaging of Cesium Distribution in Plants Used for Cesium Absorption August 19th, 2014

Сalculations with Nanoscale Smart Particles August 19th, 2014

Life on Mars? Implications of a newly discovered mineral-rich structure August 19th, 2014

Promising Ferroelectric Materials Suffer From Unexpected Electric Polarizations: Brookhaven Lab scientists find surprising locked charge polarizations that impede performance in next-gen materials that could otherwise revolutionize data-driven devices August 18th, 2014

Tools

Oxford Instruments Asylum Research Receives the 2014 Microscopy Today Innovation Award for blueDrive Photothermal Excitation August 18th, 2014

Laser makes microscopes way cooler: Cooling a nanowire probe with a laser could lead to substantial improvements in the sensitivity of atomic force probe microscopes August 15th, 2014

JPK reports on the use of AFM and advanced fluorescence microscopy at the University of Freiburg August 13th, 2014

Phasefocus reports on the use of their high-precision Lens Profiler for measuring contact lens thickness at the Brien Holden Vision Institute in Sydney, Australia August 13th, 2014

Military

New material could enhance fast and accurate DNA sequencing August 13th, 2014

On the frontiers of cyborg science August 10th, 2014

Advanced thin-film technique could deliver long-lasting medication: Nanoscale, biodegradable drug-delivery method could provide a year or more of steady doses August 6th, 2014

Air Force’s 30-year plan seeks 'strategic agility' August 1st, 2014

Research partnerships

Сalculations with Nanoscale Smart Particles August 19th, 2014

Promising Ferroelectric Materials Suffer From Unexpected Electric Polarizations: Brookhaven Lab scientists find surprising locked charge polarizations that impede performance in next-gen materials that could otherwise revolutionize data-driven devices August 18th, 2014

Nano Bonds Increase Raw Strength of Fireproof Concretes August 18th, 2014

Production of Toxic Ion Nanosorbents with High Sorption Capacity in Iran August 17th, 2014

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







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE