Nanotechnology Now

Our NanoNews Digest Sponsors



Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > How Graphene’s Electrical Properties Can Be Tuned: Fortuitous discovery in UC Riverside physics lab made using stacked layers of “wonder material”

In Bernal-stacked trilayer (ABA), the top (third) sheet is exactly on top of the lowest sheet. In rhombohedral-stacked (ABC) trilayer, the top sheet is shifted by the distance of an atom, so that the top (third) sheet and the lowest sheet form a Bernal stacking as well. Photo credit: Lau lab, UC Riverside.
In Bernal-stacked trilayer (ABA), the top (third) sheet is exactly on top of the lowest sheet. In rhombohedral-stacked (ABC) trilayer, the top sheet is shifted by the distance of an atom, so that the top (third) sheet and the lowest sheet form a Bernal stacking as well. Photo credit: Lau lab, UC Riverside.

Abstract:
An accidental discovery in a physicist's laboratory at the University of California, Riverside provides a unique route for tuning the electrical properties of graphene, nature's thinnest elastic material. This route holds great promise for replacing silicon with graphene in the microchip industry.

How Graphene’s Electrical Properties Can Be Tuned: Fortuitous discovery in UC Riverside physics lab made using stacked layers of “wonder material”

Riverside, CA | Posted on September 26th, 2011

The researchers found that stacking up three layers of graphene, like pancakes, significantly modifies the material's electrical properties. When they fabricated trilayer graphene in the lab and measured its conductance, they found, to their surprise, that depending on how the layers were stacked some of the trilayer graphene devices were conducting while others were insulating.

"What we stumbled upon is a simple and convenient ‘knob' for tuning graphene sheets' electrical properties," said Jeanie Lau, an associate professor of physics and astronomy, whose lab made the serendipitous finding.

Study results appeared online Sept. 25 in Nature Physics.

Graphene is a one-atom thick sheet of carbon atoms arranged in hexagonal rings. Bearing excellent material properties, such as high current-carrying capacity and thermal conductivity, this "wonder material" is ideally suited for creating components for semiconductor circuits and computers.

Because of the planar and chicken wire-like structure of graphene, its sheets lend themselves well to stacking in what is called ‘Bernal stacking,' the stacking fashion of graphene sheets.

In a Bernal-stacked bilayer, one corner of the hexagons of the second sheet is located above the center of the hexagons of the bottom sheet. In Bernal-stacked trilayer (ABA), the top (third) sheet is exactly on top of the lowest sheet. In rhombohedral-stacked (ABC) trilayer, the top sheet is shifted by the distance of an atom, so that the top (third) sheet and the lowest sheet form a Bernal stacking as well.

"The most stable form of trilayer graphene is ABA, which behaves like a metal," Lau explained. "Amazingly, if we simply shift the entire topmost layer by the distance of a single atom, the trilayer - now with ABC or rhombohedral stacking - becomes insulating. Why this happens is not clear as yet. It could be induced by electronic interactions. We eagerly await an explanation from theorists!"

Her lab used Raman spectroscopy to examine the graphene devices' stacking orders. Next the lab plans to investigate the nature of the insulating state in ABC-stacked graphene. In this kind of stacked graphene, they also plan to study the band gap - a range in energy, critical for digital applications, in which no electrons can exist.

"The presence of the gap in ABC-stacked graphene that arises, we believe, from enhanced electronic interactions is interesting since it is not expected from theoretical calculations," Lau said. "Understanding this gap is particularly important for the major challenge of band gap engineering in graphene electronics."

Besides graphene, Lau studies nanowires and carbon nanotubes. Her research has helped physicists gain fundamental understanding of how atoms and electrons behave when they are ruled by quantum mechanics. Her lab studies novel electrical properties that arise from the quantum confinement of atoms and charges to nanoscale systems. Her research team has shown that graphene can act as an atomic-scale billiard table, with electric charges acting as billiard balls.

Her other research interests include superconductivity, thermal management and electronic transport in nanostructures, and engineering new classes of nanoscale devices.

An educational component of Lau's research effort is the active involvement of high school, undergraduate, and graduate students, especially minority and women, in her cutting-edge research, taking advantage of the ethnic diversity of UCR's student population and local communities. She is a founding faculty member of the UCR Undergraduate Research Journal. She also organized a "Women in Physics" lunch group that provides a friendly platform for female students, postdocs and faculty members to interact.

After receiving her bachelor's degree in physics from the University of Chicago in 1994, Lau proceeded to Harvard University from where she received her master's and doctoral degrees in physics in 1997 and 2001, respectively. She joined UCR in 2004, after an appointment as a research associate in the Hewlett-Packard Laboratory.

Lau's awards and honors include a Presidential Early Career Award for Scientists and Engineers, 2009; a National Science Foundation CAREER Award, 2008; the Richter Fellowship for Undergraduate Research, 1992; a David W. Grainger Senior Scholarship, 1993; and a Robert T. Poe Faculty Development Grant from the Chinese-American Faculty Association of Southern California, 2007. She has published more than 60 research articles in peer-reviewed journals.

Lau, a member of UCR's Center for Nanoscale Science and Engineering, was joined in the research by W. Bao (the first author of the research paper), L. Jing, J. Velasco Jr., Y. Lee, G. Liu, D. Tran and M. Bockrath at UCR; B. Stanley at Caltech; M. Aykol and S. B. Cronin at the University of Southern California; D. Smirnov at the National High Magnetic Field Laboratory, Fla.; M. Koshino at Tohoku University, Japan; and E. McCann at Lancaster University, United Kingdom.

The research was funded by grants from the National Science Foundation, Office of Naval Research, and the Focus Center for Functional Engineered Nano Architectonics.

####

About University of California, Riverside
The University of California, Riverside (www.ucr.edu) is a doctoral research university, a living laboratory for groundbreaking exploration of issues critical to Inland Southern California, the state and communities around the world. Reflecting California's diverse culture, UCR's enrollment has exceeded 20,500 students. The campus will open a medical school in 2013 and has reached the heart of the Coachella Valley by way of the UCR Palm Desert Graduate Center. The campus has an annual statewide economic impact of more than $1 billion.

For more information, please click here

Contacts:
Iqbal Pittalwala
Tel: (951) 827-6050


Jeanie Lau

Copyright © University of California, Riverside

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

More about Jeanie Lau:

Department of Physics and Astronomy:

Center for Nanoscale Science and Engineering:

Related News Press

News and information

Renishaw receives Queen's Award for spectroscopy developments November 25th, 2014

JPK reports on the use of AFM and the CellHesion module to study plant cells at the University of Queensland November 25th, 2014

Vegetable oil ingredient key to destroying gastric disease bacteria: In mice, therapeutic nanoparticles dampen H. pylori bacteria and inflammation that lead to ulcers and gastric cancer November 25th, 2014

Research yields material made of single-atom layers that snap together like Legos November 25th, 2014

Blu-ray disc can be used to improve solar cell performance: Data storage pattern transferred to solar cell increases light absorption November 25th, 2014

Graphene

Research yields material made of single-atom layers that snap together like Legos November 25th, 2014

Researchers engineer improvements of technology used in digital memory November 24th, 2014

Chip Technology

Nanometrics Announces Upcoming Investor Events November 19th, 2014

A novel method for identifying the body’s ‘noisiest’ networks November 19th, 2014

Researchers create & control spin waves, lifting prospects for enhanced info processing November 17th, 2014

VDMA Electronics Production Equipment: Growth track for 2014 and 2015 confirmed: Business climate survey shows robust industry sector November 14th, 2014

Nanotubes/Buckyballs

Tesla NanoCoatings Increasing Use of SouthWest NanoTechnologies Carbon Nanotubes (CNTs) for its Infrastructure Coatings and Paints: High Quality SMW™ Specialty Multi-wall Carbon Nanotubes Incorporated into Teslan®-brand coatings used by Transportation, Oil and Gas Companies November 19th, 2014

Graphene/nanotube hybrid benefits flexible solar cells: Rice University labs create novel electrode for dye-sensitized cells November 17th, 2014

SouthWest NanoTechnologies to Demonstrate 3D Capacitive Touch Sensor Featuring Transparent, Thermoformed Carbon Nanotube Ink at Printed Electronics USA 2014 (Booth J25) -- “Conductive and Semiconducting Single-Wall Carbon Nanotube Inks” will be Topic of Company Presentation November 10th, 2014

Neural Canals Produced in Iran for Recovery of Sciatica Nerve November 8th, 2014

Nanoelectronics

Leti Will Present 17 Papers at 2014 IEDM; the Highest-ever Total Includes Four Invited Papers: Institute also Will Present its Latest Results in Key Technologies and Its Roadmap for Silicon Nano-technologies at Workshop November 13th, 2014

Breakthrough in molecular electronics paves the way for DNA-based computer circuits in the future: DNA-based programmable circuits could be more sophisticated, cheaper and simpler to make October 27th, 2014

NIST offers electronics industry 2 ways to snoop on self-organizing molecules October 22nd, 2014

Materials for the next generation of electronics and photovoltaics: MacArthur Fellow develops new uses for carbon nanotubes October 21st, 2014

Discoveries

Lawrence Livermore researchers develop efficient method to produce nanoporous metals November 25th, 2014

Vegetable oil ingredient key to destroying gastric disease bacteria: In mice, therapeutic nanoparticles dampen H. pylori bacteria and inflammation that lead to ulcers and gastric cancer November 25th, 2014

Research yields material made of single-atom layers that snap together like Legos November 25th, 2014

Blu-ray disc can be used to improve solar cell performance: Data storage pattern transferred to solar cell increases light absorption November 25th, 2014

Announcements

Renishaw receives Queen's Award for spectroscopy developments November 25th, 2014

JPK reports on the use of AFM and the CellHesion module to study plant cells at the University of Queensland November 25th, 2014

Vegetable oil ingredient key to destroying gastric disease bacteria: In mice, therapeutic nanoparticles dampen H. pylori bacteria and inflammation that lead to ulcers and gastric cancer November 25th, 2014

Research yields material made of single-atom layers that snap together like Legos November 25th, 2014

Grants/Awards/Scholarships/Gifts/Contests/Honors/Records

Renishaw receives Queen's Award for spectroscopy developments November 25th, 2014

A*STAR SIMTech wins international award for breaking new ground in actuators: SIMTech invention can be used in an array of industries, and is critical for next generation ultra-precision systems November 24th, 2014

SUNY Poly Student Awarded Fellowship with the U.S. Department of Energy's Postgraduate Research Program: Ph.D. Candidate Accepts Postmaster's Appointment To Conduct Research At Albany NanoTech Complex November 13th, 2014

MEMS Industry Group's 10th Annual Executive Conference Showcases Rapid Innovation in MEMS/Sensors: Emphasizes Spirit of Collaboration, Supporting First Open-Source Algorithm Community, New Standardization Efforts November 10th, 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