Nanotechnology Now





Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > Two Graphene Layers May Be Better Than One

NIST
NIST measurements show that interactions of the graphene layers with the insulating substrate material causes electrons (red, down arrow) and electron holes (blue, up arrow) to collect in "puddles". The differing charge densities creates the random pattern of alternating dipoles and electron band gaps that vary across the layers.
NIST
NIST measurements show that interactions of the graphene layers with the insulating substrate material causes electrons (red, down arrow) and electron holes (blue, up arrow) to collect in "puddles". The differing charge densities creates the random pattern of alternating dipoles and electron band gaps that vary across the layers.

Abstract:
Researchers at the National Institute of Standards and Technology (NIST) have shown that the electronic properties of two layers of graphene vary on the nanometer scale. The surprising new results reveal that not only does the difference in the strength of the electric charges between the two layers vary across the layers, but they also actually reverse in sign to create randomly distributed puddles of alternating positive and negative charges. Reported in Nature Physics,* the new measurements bring graphene a step closer to being used in practical electronic devices.

Two Graphene Layers May Be Better Than One

Gaithersburg, MD | Posted on April 28th, 2011

Graphene, a single layer of carbon atoms, is prized for its remarkable properties, not the least of which is the way it conducts electrons at high speed. However, the lack of what physicists call a band gap—an energetic threshold that makes it possible to turn a transistor on and off—makes graphene ill-suited for digital electronic applications.

Researchers have known that bilayer graphene, consisting of two stacked graphene layers, acts more like a semiconductor when immersed in an electric field.

According to NIST researcher Nikolai Zhitenev, the band gap may also form on its own due to variations in the sheets' electrical potential caused by interactions among the graphene electrons or with the substrate (usually a nonconducting, or insulating material) that the graphene is placed upon.
NIST fellow Joseph Stroscio says that their measurements indicate that interactions with the disordered insulating substrate material causes pools of electrons and electron holes (basically, the absence of electrons) to form in the graphene layers. Both electron and hole "pools" are deeper on the bottom layer because it is closer to the substrate. This difference in "pool" depths, or charge density, between the layers creates the random pattern of alternating charges and the spatially varying band gap.

Manipulating the purity of the substrate could give researchers a way to finely control graphene's band gap and may eventually lead to the fabrication of graphene-based transistors that can be turned on and off like a semiconductor.

Still, as shown in the group's previous work**, while these substrate interactions open the door to graphene's use as a practical electronic material, they lower the window on speed. Electrons do not move as well through substrate-mounted bilayer graphene; however, this may likely be compensated for by engineering the graphene/substrate interactions.

Stroscio's team plans to explore further the role that substrates may play in the creation and control of band gaps in graphene by using different substrate materials. If the substrate interactions can be reduced far enough, says Stroscio, the exotic quantum properties of bilayer graphene may be harnessed to create a new quantum field effect transistor.

* G. Rutter, S. Jung, N. Klimov, D. Newell, N. Zhitenev and J. Stroscio. Microscopic polarization in bilayer graphene. Nature Physics. Published online April 24, 2011.

####

For more information, please click here

Contacts:
Mark Esser

(301) 975-8735

Copyright © Newswise

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

** "See the Jan. 19, 2011, Tech Beat article "Real-World Graphene Devices May Have a Bumpy Ride" at:

Related News Press

News and information

Rice University boots up powerful microscopes: New electron microscopes will capture images at subnanometer resolution June 29th, 2015

The Hydrogen-Fuel cell will revolutionize the economy of the world: New non-platinum and nanosized catalyst for polymer electrolyte fuel cell June 29th, 2015

June 29th, 2015

Efforts to Use Smart Nanocarriers to Cure Leukemia Yield Promising Results June 29th, 2015

Graphene

Angstron Materials Appoints VP for Business Development And Engineering June 27th, 2015

Spain nanotechnology featured at NANO KOREA 2015 June 26th, 2015

Breakthrough graphene production could trigger revolution in artificial skin development June 25th, 2015

Towards graphene biosensors June 24th, 2015

Govt.-Legislation/Regulation/Funding/Policy

X-rays and electrons join forces to map catalytic reactions in real-time: New technique combines electron microscopy and synchrotron X-rays to track chemical reactions under real operating conditions June 29th, 2015

Graphene breakthrough as Bosch creates magnetic sensor 100 times more sensitive than silicon equivalent June 28th, 2015

The peaks and valleys of silicon: Team of USC Viterbi School of Engineering Researchers introduce new layered semiconducting materials as silicon alternative June 27th, 2015

Building a better semiconductor: Research led by Michigan State University could someday lead to the development of new and improved semiconductors June 27th, 2015

Chip Technology

Making new materials with micro-explosions: ANU media release: Scientists have made exotic new materials by creating laser-induced micro-explosions in silicon, the common computer chip material June 29th, 2015

The peaks and valleys of silicon: Team of USC Viterbi School of Engineering Researchers introduce new layered semiconducting materials as silicon alternative June 27th, 2015

Building a better semiconductor: Research led by Michigan State University could someday lead to the development of new and improved semiconductors June 27th, 2015

Opening a new route to photonics Berkeley lab researchers find way to control light in densely packed nanowaveguides June 27th, 2015

Discoveries

The Hydrogen-Fuel cell will revolutionize the economy of the world: New non-platinum and nanosized catalyst for polymer electrolyte fuel cell June 29th, 2015

June 29th, 2015

Efforts to Use Smart Nanocarriers to Cure Leukemia Yield Promising Results June 29th, 2015

Making new materials with micro-explosions: ANU media release: Scientists have made exotic new materials by creating laser-induced micro-explosions in silicon, the common computer chip material June 29th, 2015

Announcements

The Hydrogen-Fuel cell will revolutionize the economy of the world: New non-platinum and nanosized catalyst for polymer electrolyte fuel cell June 29th, 2015

June 29th, 2015

Efforts to Use Smart Nanocarriers to Cure Leukemia Yield Promising Results June 29th, 2015

Making new materials with micro-explosions: ANU media release: Scientists have made exotic new materials by creating laser-induced micro-explosions in silicon, the common computer chip material June 29th, 2015

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