Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Graphane yields new potential

Rice researchers created these fanciful images of electron densities from their graphane-embedded quantum dot calculations. The isosurfaces depict electrons in the valance band that, in reality, would be confined within the quantum dot, and demonstrate that very little charge would leak from the hydrogen-defined boundaries of such a dot. CREDIT: EVGENI PENEV/ABHISHEK SINGH
Rice researchers created these fanciful images of electron densities from their graphane-embedded quantum dot calculations. The isosurfaces depict electrons in the valance band that, in reality, would be confined within the quantum dot, and demonstrate that very little charge would leak from the hydrogen-defined boundaries of such a dot. CREDIT: EVGENI PENEV/ABHISHEK SINGH

Abstract:
Rice physicists dig theoretical wells to mine quantum dots

Graphane yields new potential

Houston, TX | Posted on May 25th, 2010

Graphane is the material of choice for physicists on the cutting edge of materials science, and Rice University researchers are right there with the pack - and perhaps a little ahead.

Researchers mentored by Boris Yakobson, a Rice professor of mechanical engineering and materials science and of chemistry, have discovered the strategic extraction of hydrogen atoms from a two-dimensional sheet of graphane naturally opens up spaces of pure graphene that look - and act - like quantum dots.

That opens up a new world of possibilities for an ever-shrinking class of nanoelectronics that depend on the highly controllable semiconducting properties of quantum dots, particularly in the realm of advanced optics.

The theoretical work by Abhishek Singh and Evgeni Penev, both postdoctoral researchers in co-author Yakobson's group, was published online last week in the journal ACS Nano and will be on the cover of the print version in June. Rice was recently named the world's No. 1 institution for materials science research by a United Kingdom publication.

Graphene has become the Flat Stanley of materials. The one-atom-thick, honeycomb-like form of carbon may be two-dimensional, but it seems to be everywhere, touted as a solution to stepping beyond the limits of Moore's Law.

Graphane is simply graphene modified by hydrogen atoms added to both sides of the matrix, which makes it an insulator. While it's still technically only a single atom thick, graphane offers great possibilities for the manipulation of the material's semiconducting properties.

Quantum dots are crystalline molecules from a few to many atoms in size that interact with light and magnetic fields in unique ways. The size of a dot determines its band gap - the amount of energy needed to close the circuit - and makes it tunable to a precise degree. The frequencies of light and energy released by activated dots make them particularly useful for chemical sensors, solar cells, medical imaging and nanoscale circuitry.

Singh and Penev calculated that removing islands of hydrogen from both sides of a graphane matrix leaves a well with all the properties of quantum dots, which may also be useful in creating arrays of dots for many applications.

"We arrived at these ideas from an entirely different study of energy storage in a form of hydrogen adsorption on graphene," Yakobson said. "Abhishek and Evgeni realized that this phase transformation (from graphene to graphane), accompanied by the change from metal to insulator, offers a novel palette for nanoengineering."

Their work revealed several interesting characteristics. They found that when chunks of the hydrogen sublattice are removed, the area left behind is always hexagonal, with a sharp interface between the graphene and graphane. This is important, they said, because it means each dot is highly contained; calculations show very little leakage of charge into the graphane host material. (How, precisely, to remove hydrogen atoms from the lattice remains a question for materials scientists, who are working on it, they said.)

"You have an atom-like spectra embedded within a media, and then you can play with the band gap by changing the size of the dot," Singh said. "You can essentially tune the optical properties."

Along with optical applications, the dots may be useful in single-molecule sensing and could lead to very tiny transistors or semiconductor lasers, he said.

Challenges remain in figuring out how to make arrays of quantum dots in a sheet of graphane, but neither Singh nor Penev sees the obstacles as insurmountable.

"We think the major conclusions in the paper are enough to excite experimentalists," said Singh, who will soon leave Rice to become an assistant professor at the Indian Institute of Science in Bangalore. "Some are already working in the directions we explored."

"Their work is actually supporting what we're suggesting, that you can do this patterning in a controlled way," Penev said.

When might their calculations bear commercial fruit? "That's a tough question," Singh said. "It won't be that far, probably -- but there are challenges. I don't know that we can give it a time frame, but it could happen soon."

Funding from the Office of Naval Research supported the work. Computations were performed at the Department of Defense Supercomputing Resource Center at the Air Force Research Laboratory.

####

About Rice University
Located in Houston, Rice University is consistently ranked one of America's best teaching and research universities. Known for its "unconventional wisdom," Rice is distinguished by its: size -- 3,102 undergraduates and 2,237 graduate students; selectivity -- 12 applicants for each place in the freshman class; resources -- an undergraduate student-to-faculty ratio of 5-to-1; sixth largest endowment per student among American private research universities; residential college system, which builds communities that are both close-knit and diverse; and collaborative culture, which crosses disciplines, integrates teaching and research, and intermingles undergraduate and graduate work.

For more information, please click here

Contacts:
David Ruth
713-348-6327

Copyright © Rice University

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

Basque researchers turn light upside down February 23rd, 2018

Stiffness matters February 23rd, 2018

Imaging individual flexible DNA 'building blocks' in 3-D: Berkeley Lab researchers generate first images of 129 DNA structures February 22nd, 2018

'Memtransistor' brings world closer to brain-like computing: Combined memristor and transistor can process information and store memory with one device February 22nd, 2018

Govt.-Legislation/Regulation/Funding/Policy

Imaging individual flexible DNA 'building blocks' in 3-D: Berkeley Lab researchers generate first images of 129 DNA structures February 22nd, 2018

'Memtransistor' brings world closer to brain-like computing: Combined memristor and transistor can process information and store memory with one device February 22nd, 2018

Arrowhead Receives Regulatory Clearance to Begin Phase 1 Study of ARO-AAT for Treatment of Alpha-1 Liver Disease February 22nd, 2018

Computers aid discovery of new, inexpensive material to make LEDs with high color quality February 20th, 2018

Possible Futures

Basque researchers turn light upside down February 23rd, 2018

Stiffness matters February 23rd, 2018

Developing reliable quantum computers February 22nd, 2018

Imaging individual flexible DNA 'building blocks' in 3-D: Berkeley Lab researchers generate first images of 129 DNA structures February 22nd, 2018

Academic/Education

Luleň University of Technology is using the Deben CT5000TEC stage to perform x-ray microtomography experiments with the ZEISS Xradia 510 Versa to understand deformation and strain inside inhomogeneous materials November 7th, 2017

Park Systems Announces the Grand Opening of the Park NanoScience Center at SUNY Polytechnic Institute November 3rd, 2017

Two Scientists Receive Grants to Develop New Materials: Chad Mirkin and Monica Olvera de la Cruz recognized by Sherman Fairchild Foundation August 16th, 2017

Moving at the Speed of Light: University of Arizona selected for high-impact, industrial demonstration of new integrated photonic cryogenic datalink for focal plane arrays: Program is major milestone for AIM Photonics August 10th, 2017

Nanotubes/Buckyballs/Fullerenes/Nanorods

Nanotube fibers in a jiffy: Rice University lab makes short nanotube samples by hand to dramatically cut production time January 11th, 2018

Touchy nanotubes work better when clean: Rice, Swansea scientists show that decontaminating nanotubes can simplify nanoscale devices January 4th, 2018

Paving the way for a non-electric battery to store solar energy: UMass Amherst scientists say a polymer chain organized like a string of Christmas lights assists energy storage December 22nd, 2017

Nanotubes go with the flow to penetrate brain tissue: Rice University scientists, engineers develop microfluidic devices, microelectrodes for gentle implantation December 19th, 2017

Nanoelectronics

Basque researchers turn light upside down February 23rd, 2018

Graphene on toast, anyone? Rice University scientists create patterned graphene onto food, paper, cloth, cardboard February 13th, 2018

Vanadium dioxyde: A revolutionary material for tomorrow's electronics: Phase-chance switch can now be performed at higher temperatures February 5th, 2018

Measuring the temperature of two-dimensional materials at the atomic level February 3rd, 2018

Announcements

Basque researchers turn light upside down February 23rd, 2018

Stiffness matters February 23rd, 2018

Histology in 3-D: New staining method enables Nano-CT imaging of tissue samples February 22nd, 2018

Developing reliable quantum computers February 22nd, 2018

Quantum Dots/Rods

Moving nanoparticles using light and magnetic fields January 25th, 2018

Tweaking quantum dots powers-up double-pane solar windows: Engineered quantum dots could bring down the cost of solar electricity January 2nd, 2018

Quantum communications bend to our needs: By changing the wavelengths of entangled photons to those used in telecommunications, researchers see quantum technology take a major leap forward September 28th, 2017

Band Gaps, Made to Order: Engineers create atomically thin superlattice materials with precision September 26th, 2017

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project