Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

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

Chains of nanogold – forged with atomic precision September 23rd, 2016

Tattoo therapy could ease chronic disease: Rice-made nanoparticles tested at Baylor College of Medicine may help control autoimmune diseases September 23rd, 2016

Nanotech Grants Options September 22nd, 2016

Coffee-infused foam removes lead from contaminated water September 21st, 2016

Graphene/ Graphite

Graphene nanoribbons show promise for healing spinal injuries: Rice University scientists develop Texas-PEG to help knit severed, damaged spinal cords September 19th, 2016

Semiconducting inorganic double helix: New flexible semiconductor for electronics, solar technology and photo catalysis September 15th, 2016

Bringing graphene speakers to the mobile market (video) September 12th, 2016

Atomic scale pipes available on demand and by design September 9th, 2016

Chip Technology

Mexican scientist in the Netherlands seeks to achieve data transmission ... speed of light September 20th, 2016

Towards Stable Propagation of Light in Nano-Photonic Fibers September 20th, 2016

PHENOMEN is a FET-Open Research Project aiming to lay the foundations a new information technology September 19th, 2016

NIST Patents Single-Photon Detector for Potential Encryption and Sensing Apps September 16th, 2016

Nanotubes/Buckyballs/Fullerenes

Semiconducting inorganic double helix: New flexible semiconductor for electronics, solar technology and photo catalysis September 15th, 2016

World's most powerful X-ray takes a 'sledgehammer' to molecules September 14th, 2016

Researchers design solids that control heat with spinning superatoms: Carnegie Mellon University and Columbia University collaborators discover the cause of vastly different thermal conductivities in superatomic structural analogues September 8th, 2016

For first time, carbon nanotube transistors outperform silicon September 8th, 2016

Nanoelectronics

Mexican scientist in the Netherlands seeks to achieve data transmission ... speed of light September 20th, 2016

GLOBALFOUNDRIES to Deliver Industry’s Leading-Performance Offering of 7nm FinFET Technology: Company extends its leading-edge roadmap for products demanding the ultimate processing power September 15th, 2016

Semiconducting inorganic double helix: New flexible semiconductor for electronics, solar technology and photo catalysis September 15th, 2016

A versatile method to pattern functionalized nanowires: A team of researchers from Hokkaido University has developed a versatile method to pattern the structure of 'nanowires,' providing a new tool for the development of novel nanodevices September 9th, 2016

Discoveries

Chains of nanogold – forged with atomic precision September 23rd, 2016

Tattoo therapy could ease chronic disease: Rice-made nanoparticles tested at Baylor College of Medicine may help control autoimmune diseases September 23rd, 2016

Speedy bacteria detector could help prevent foodborne illnesses September 21st, 2016

Coffee-infused foam removes lead from contaminated water September 21st, 2016

Announcements

Chains of nanogold – forged with atomic precision September 23rd, 2016

Tattoo therapy could ease chronic disease: Rice-made nanoparticles tested at Baylor College of Medicine may help control autoimmune diseases September 23rd, 2016

Nanotech Grants Options September 22nd, 2016

Coffee-infused foam removes lead from contaminated water September 21st, 2016

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

Tattoo therapy could ease chronic disease: Rice-made nanoparticles tested at Baylor College of Medicine may help control autoimmune diseases September 23rd, 2016

Semiconducting inorganic double helix: New flexible semiconductor for electronics, solar technology and photo catalysis September 15th, 2016

Bringing graphene speakers to the mobile market (video) September 12th, 2016

Novel nanoscale detection of real-time DNA amplification holds promise for diagnostics: Research team led by Nagoya University develop a label-free method for detecting DNA amplification in real time based on refractive index changes in diffracted light September 12th, 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