Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

UCR scientists manipulate ripples in graphene, enabling strain-based graphene electronics

28.07.2009
Study is first to experimentally quantify thermal contraction of graphene

Graphene is nature's thinnest elastic material and displays exceptional mechanical and electronic properties. Its one-atom thickness, planar geometry, high current-carrying capacity and thermal conductivity make it ideally suited for further miniaturizing electronics through ultra-small devices and components for semiconductor circuits and computers.

But one of graphene's intrinsic features is ripples, similar to those seen on plastic wrap tightly pulled over a clamped edge. Induced by pre-existing strains in graphene, these ripples can strongly affect graphene's electronic properties, and not always favorably.

If the ripples can be controlled, however, they can be used to advantage in nanoscale devices and electronics, opening up a new arena in graphene engineering: strain-based devices.

UC Riverside's Chun Ning (Jeanie) Lau and colleagues now report the first direct observation and controlled creation of one- and two-dimensional ripples in graphene sheets. Using simple thermal manipulation, the researchers produced the ripples, and controlled their orientation, wavelength and amplitude.

"When the graphene sheets are stretched across a pair of parallel trenches, they spontaneously form nearly periodic ripples," Lau explained. "When these sheets are heated up, they actually contract, so the ripples disappear. When they are cooled down to room temperature, the ripples re-appear, with ridges at right angle to the edges of the trenches. This phenomenon is similar to what happens to a piece of thin plastic wrap that covers a container and heated in a microwave oven."

The unusual thermal contraction of graphene had been predicted theoretically, but Lau's lab is the first to demonstrate and quantify the phenomenon experimentally.

Study results appear July 26 in the advance online publication of Nature Nanotechnology.

Because graphene is both an excellent conductor and the thinnest elastic membrane, the ripples could have profound implications for graphene-based electronics.

"This is because graphene's ability to conduct electricity is expected to vary with the local shape of the membrane," Lau said. "For instance, the ripples may produce effective magnetic fields that can be used to steer and manipulate electrons in a nanoscale device without an external magnet."

Lau, an associate professor of physics and a member of UCR's Center for Nanoscale Science and Engineering, and her colleagues examined the ripples' morphology using a scanning electron microscope and an atomic force microscope. They found that almost all the graphene membranes underwent dramatic morphological changes when heated, displaying significant alterations in the ripple geometry, a buckling of the graphene membrane, or both.

Their experimental system, which involved a stage inside a scanning electron microscope (SEM) with a built-in heater, thermometer and several electrical feed-throughs, enabled them to image graphene while it was being heated and explore the interplay between graphene's mechanical, thermal and electrical properties.

"Our result has important implications for controlling thermally induced stress in graphene electronics," Lau said. "Our ability to control and manipulate the ripples in graphene sheets represents the first step towards strain-based graphene engineering. We show that suspended graphene is almost invariably rippled, and this may need to be considered in the interpretation of a broad array of existing and future research."

Proposed to supplement or replace silicon as the main electronic material, graphene is a single layer of graphite. Even though graphite has been studied for decades, the single sheet first was isolated experimentally only in 2004. Graphene's structure is a two-dimensional honeycomb lattice of carbon atoms. Structurally, it is related to carbon nanotubes (tiny hollow tubes formed by rolling up sheets of graphene) and buckyballs (hollow carbon molecules that form a closed cage).

Lau, who earlier this month was named one of the recipients of the Presidential Early Career Awards for Scientists and Engineers for the 2008 competition, joined UCR in 2004. She was joined in the 18-month study by UCR's Wenzhong Bao (first author), Feng Miao, Zhen Chen, Hang Zhang, Wanyoung Jang and Chris Dames.

The research was supported in part by grants from the National Science Foundation and the Office of Naval Research.

The University of California, Riverside 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 of about 17,000 is expected to grow to 21,000 students by 2020. The campus is planning a medical school 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. To learn more, visit www.ucr.edu or call (951) UCR-NEWS.

Iqbal Pittalwala | EurekAlert!
Further information:
http://www.ucr.edu

More articles from Power and Electrical Engineering:

nachricht Waste from paper and pulp industry supplies raw material for development of new redox flow batteries
12.10.2017 | Johannes Gutenberg-Universität Mainz

nachricht Low-cost battery from waste graphite
11.10.2017 | Empa - Eidgenössische Materialprüfungs- und Forschungsanstalt

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Electrode materials from the microwave oven

19.10.2017 | Materials Sciences

New material for digital memories of the future

19.10.2017 | Materials Sciences

Physics boosts artificial intelligence methods

19.10.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>