Nanotechnology Now







Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > Making Contact

Georgia Tech researchers Markus Kindermann, Mei-Yin Chou and Salvador Barraza-Lopez pose with a graphic from their study of metal contacts on graphene. Georgia Tech Photo
Georgia Tech researchers Markus Kindermann, Mei-Yin Chou and Salvador Barraza-Lopez pose with a graphic from their study of metal contacts on graphene. Georgia Tech Photo

Abstract:
New Study Quantifies the Electron Transport Effects of Placing Metal Contacts onto Graphene

By John Toon

Making Contact

Atlanta, GA | Posted on March 15th, 2010

Using large-scale supercomputer calculations, researchers have analyzed how the placement of metallic contacts on graphene changes the electron transport properties of the material as a factor of junction length, width and orientation. The work is believed to be the first quantitative study of electron transport through metal-graphene junctions to examine earlier models in significant detail.

Information on the ways in which attaching metal contacts affects electron transport in graphene will be important to scientists studying the material - and to designers who may one day fabricate electronic devices from the carbon-lattice material.

"Graphene devices will have to communicate with the external world, and that means we will have to fabricate contacts to transport current and data," said Mei-Yin Chou, a professor and department chair in the School of Physics at the Georgia Institute of Technology. "When they put metal contacts onto graphene to measure transport properties, researchers and device designers need to know that they may not be measuring the instrinsic properties of pristine graphene. Coupling between the contacts and the material must be taken into account."

Information on the effects of metal contacts on graphene was reported in the journal Physical Review Letters on February 19th. The research was supported by the U.S. Department of Energy, and involved interactions with researchers at the National Science Foundation (NSF)-supported Materials Research Science and Engineering Center (MRSEC) at Georgia Tech.

Using large-scale, first-principles calculations done at two different NSF-supported supercomputer centers, the Georgia Tech research team - which included postdoctoral fellows Salvador Barraza-Lopez and Mihajlo Vanevic, and assistant professor Markus Kindermann - conducted detailed atomic-level calculations of aluminum contacts grown on graphene.

The calculations studied two contacts up to 14 nanometers apart, with graphene suspended between them. In their calculations, the researchers allowed the aluminum to grow as it would in the real world, then studied how electron transfer was induced in the area surrounding the contacts.

"People have been able to come up with phenomenological models that they use to find out what the effects are with metallic contacts," Chou explained. "Our calculations went a few steps farther because we built contacts atom-by-atom. We built atomistically-resolved contacts, and by doing that, we solved this problem at the atomic level and tried to do everything consistent with quantum mechanics."

Because metals typically have excess electrons, physically attaching the contacts to graphene causes a charge transfer from the metal. Charge begins to be transferred as soon as the contracts are constructed, but ultimately the two materials reach equilibrium, Chou said.

The study showed that charge transfer at the leads and into the freestanding section of the material creates an electron-hole asymmetry in the conductance. For leads that are sufficiently long, the effect creates two conductance minima at the energies of the Dirac points for the suspended and clamped regions of the graphene, according to Barraza-Lopez.

"These results could be important to the design of future graphene devices," he said. "Edge effects and the impact of nanoribbon width have been studied in significant detail, but the effects of charge transfer at the contacts may potentially be just as important."

The researchers modeled aluminum, but believe their results will apply to other metals such as copper and gold that do not form chemical bonds with graphene. However, other metals such as chromium and titanium do chemically alter the material, so the effects they have on electron transport may be different.

Beyond the new information provided by the calculations, the research further proposes quantitative models that can be used under certain circumstances to describe the impact of the contacts.

"Earlier models had been based on physical insights, but nobody really knew how faithfully they described the material," Kindermann said. "This is the first calculation to show that these earlier models apply under certain circumstances for the systems that we studied."

Data from the study may one day help device designers engineer graphene circuits by helping them understand the effects they are seeing.

"When we modify graphene, we need to understand what changes occur as a result of adding materials," added Chou. "This is really fundamental research to understand these effects and to have a numerical prediction for what is going on. We are helping to understand the basic physics of graphene."

This research was supported by Department of Energy grant DE-FG02-97ER45632. Comments and conclusions in this article are those of the researchers and do not necessarily reflect the views of the Department of Energy.

####

About Georgia Institute of Technology
The Georgia Institute of Technology is one of the nation's top research universities, distinguished by its commitment to improving the human condition through advanced science and technology.

Georgia Tech's campus occupies 400 acres in the heart of the city of Atlanta, where 20,000 undergraduate and graduate students receive a focused, technologically based education.

For more information, please click here

Contacts:
John Toon
404-894-6986


Abby Vogel
404-385-3364

Copyright © Georgia Institute of Technology

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

Mass spectrometers with optimised hydrogen pumping March 1st, 2015

Imec Demonstrates Compact Wavelength-Division Multiplexing CMOS Silicon Photonics Transceiver March 1st, 2015

onic Present breakthrough in CMOS-based Transceivers for mm-Wave Radar Systems March 1st, 2015

Graphene Shows Promise In Eradication Of Stem Cancer Cells March 1st, 2015

Preparing for Nano

Durnham University's DEEPEN project comes to a close September 26th, 2012

Technical Seminar at ANFoS 2012 August 22nd, 2012

Nanotechnology shows we can innovate without economic growth April 12th, 2012

Thailand to host NanoThailand 2012 December 18th, 2011

Govt.-Legislation/Regulation/Funding/Policy

First detailed microscopy evidence of bacteria at the lower size limit of life: Berkeley Lab research provides comprehensive description of ultra-small bacteria February 28th, 2015

Warming up the world of superconductors: Clusters of aluminum metal atoms become superconductive at surprisingly high temperatures February 25th, 2015

SUNY Poly CNSE Researchers and Corporate Partners to Present Forty Papers at Globally Recognized Lithography Conference: SUNY Poly CNSE Research Group Awarded Both ‘Best Research Paper’ and ‘Best Research Poster’ at SPIE Advanced Lithography 2015 forum February 25th, 2015

European roadmap for graphene science and technology published February 25th, 2015

Academic/Education

NanoTecNexus Launches New App for Learning About Nanotechnology—STEM Education Project Spearheaded by Interns February 26th, 2015

SUNY Poly CNSE Researchers and Corporate Partners to Present Forty Papers at Globally Recognized Lithography Conference: SUNY Poly CNSE Research Group Awarded Both ‘Best Research Paper’ and ‘Best Research Poster’ at SPIE Advanced Lithography 2015 forum February 25th, 2015

KIT Increases Commitment in Asia: DAAD Funds Two New Projects: Strategic Partnerships with Chinese Universities and Communi-cation Technologies Network February 22nd, 2015

Minus K Technology Announces Its 2015 Vibration Isolator Educational Giveaway to U.S. Colleges and Universities February 18th, 2015

Chip Technology

onic Present breakthrough in CMOS-based Transceivers for mm-Wave Radar Systems March 1st, 2015

New nanowire structure absorbs light efficiently: Dual-type nanowire arrays can be used in applications such as LEDs and solar cells February 25th, 2015

SUNY Poly CNSE Researchers and Corporate Partners to Present Forty Papers at Globally Recognized Lithography Conference: SUNY Poly CNSE Research Group Awarded Both ‘Best Research Paper’ and ‘Best Research Poster’ at SPIE Advanced Lithography 2015 forum February 25th, 2015

Ultra-thin nanowires can trap electron 'twisters' that disrupt superconductors February 24th, 2015

Nanoelectronics

New nanowire structure absorbs light efficiently: Dual-type nanowire arrays can be used in applications such as LEDs and solar cells February 25th, 2015

Ultra-thin nanowires can trap electron 'twisters' that disrupt superconductors February 24th, 2015

Improved fire detection with new ultra-sensitive, ultraviolet light sensor February 17th, 2015

Nanotechnology facility planned in Lund, Sweden: A production facility for start-ups in the field of nanotechnology may be built in the Science Village in Lund, a world-class research and innovation village that is also home to ESS, the European Spallation Source February 15th, 2015

Announcements

Imec, Murata, and Huawei Introduce Breakthrough Solution for TX-to-RX Isolation in Reconfigurable, Multiband Front-End Modules for Mobile Phones: Electrical-Balance Duplexers Pave the Way to Integrated Solution for TX-to-RX Isolation March 1st, 2015

Imec Demonstrates Compact Wavelength-Division Multiplexing CMOS Silicon Photonics Transceiver March 1st, 2015

onic Present breakthrough in CMOS-based Transceivers for mm-Wave Radar Systems March 1st, 2015

Graphene Shows Promise In Eradication Of Stem Cancer Cells March 1st, 2015

Quantum nanoscience

Quantum many-body systems on the way back to equilibrium: Advances in experimental and theoretical physics enable a deeper understanding of the dynamics and properties of quantum many-body systems February 25th, 2015

Quantum research past, present and future for discussion at AAAS February 16th, 2015

Exotic states materialize with supercomputers February 12th, 2015

Graphene displays clear prospects for flexible electronics February 2nd, 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







© Copyright 1999-2015 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE