Nanotechnology Now

Our NanoNews Digest Sponsors





Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > MIT research: A new twist on nanowires: Technology developed at MIT can control the composition and structure of these tiny wires as they grow.

Abstract:
Nanowires — microscopic fibers that can be "grown" in the lab — are a hot research topic today, with a variety of potential applications including light-emitting diodes (LEDs) and sensors. Now, a team of MIT researchers has found a way of precisely controlling the width and composition of these tiny strands as they grow, making it possible to grow complex structures that are optimally designed for particular applications.

MIT research: A new twist on nanowires: Technology developed at MIT can control the composition and structure of these tiny wires as they grow.

Cambridge, MA | Posted on February 22nd, 2012

The results are described in a new paper authored by MIT assistant professor of materials science and engineering Silvija Gradečak and her team, published in the journal Nano Letters.

Nanowires have been of great interest because structures with such tiny dimensions — typically just a few tens of nanometers, or billionths of a meter, in diameter — can have very different properties than the same materials have in their larger form. That's in part because at such minuscule scales, quantum confinement effects — based on the behavior of electrons and phonons within the material — begin to play a significant role in the material's behavior, which can affect how it conducts electricity and heat or interacts with light.

In addition, because nanowires have an especially large amount of surface area in relation to their volume, they are particularly well-suited for use as sensors, Gradečak says.

Her team was able to control and vary both the size and composition of individual wires as they grew. Nanowires are grown by using "seed" particles, metal nanoparticles that determine the size and composition of the nanowire. By adjusting the amount of gases used in growing the nanowires, Gradečak and her team were able to control the size and composition of the seed particles and, therefore, the nanowires as they grew. "We're able to control both of these properties simultaneously," she says. While the researchers carried out their nanowire-growth experiments with indium nitride and indium gallium nitride, they say the same technique could be applied to a variety of different materials.

These nanowires are far too small to see with the naked eye, but the team was able to observe them using electron microscopy, making adjustments to the growth process based on what they learned about the growth patterns. Using a process called electron tomography, they were able to reconstruct the three-dimensional shape of individual nanoscale wires. In a related study recently published in the journal Nanoscale, the team also used a unique electron-microscopy technique called cathodoluminescence to observe what wavelengths of light are emitted from different regions of individual nanowires.

Precisely structured nanowires could facilitate a new generation of semiconductor devices, Gradečak says. Such control of nanowire geometry and composition could enable devices with better functionality than conventional thin-film devices made of the same materials, she says.

One likely application of the materials developed by Gradečak and her team is in LED light bulbs, which have far greater durability and are more energy-efficient than other lighting alternatives. The most important colors of light to produce from LEDs are in the blue and ultraviolet range; zinc oxide and gallium nitride nanowires produced by the MIT group can potentially produce these colors very efficiently and at low cost, she says.

While LED light bulbs are available today, they are relatively expensive. "For everyday applications, the high cost is a barrier," Gradečak says. One big advantage of this new approach is that it could enable the use of much less expensive substrate materials — a major part of the cost of such devices, which today typically use sapphire or silicon carbide substrates. The nanowire devices have the potential to be more efficient as well, she says.

Such nanowires could also find applications in solar-energy collectors for lower-cost solar panels. Being able to control the shape and composition of the wires as they grow could make it possible to produce very efficient collectors: The individual wires form defect-free single crystals, reducing the energy lost due to flaws in the structure of conventional solar cells. And by controlling the exact dimensions of the nanowires, it's possible to control which wavelengths of light they are "tuned" to, either for producing light in an LED or for collecting light in a solar panel.

Complex structures made of nanowires with varying diameters could also be useful in new thermoelectric devices to capture waste heat and turn it into useful electric power. By varying the composition and diameter of the wires along their length, it's possible to produce wires that conduct electricity well but heat poorly — a combination that is hard to achieve in most materials, but is key to efficient thermoelectric generating systems.

The nanowires can be produced using tools already in use by the semiconductor industry, so the devices should be relatively easy to gear up for mass production, the team says.

In addition to Gradečak, the Nano Letters paper was co-authored by MIT graduate student Sam Crawford, Sung Keun Lim PhD '11 and researcher Georg Haberfehlner of the research and technology organization CEA-Leti in Grenoble, France. The Nanoscale paper was co-authored by MIT graduate student Xiang Zhou, Megan Brewster PhD '11 and postdoc Ming-Yen Lu. The work was supported by the MIT Center for Excitonics, the U.S. Department of Energy, the MIT-France MISTI program and the National Science Foundation.

Written by David L. Chandler, MIT News Office

####

For more information, please click here

Contacts:
Kimberly Allen

617-253-2702

Copyright © Massachusetts 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 Links

Silvija Gradečak:

Department of Materials Science and Engineering:

Gradečak Group:

Related News Press

News and information

Organometallics welcomes new editor-in-chief: Paul Chirik, Ph.D. July 22nd, 2014

The Hiden EQP Plasma Diagnostic with on-board MCA July 22nd, 2014

Iran to Hold 3rd Int'l Forum on Nanotechnology Economy July 22nd, 2014

Nanometrics Announces Upcoming Investor Events July 22nd, 2014

Display technology/LEDs/SS Lighting/OLEDs

Martini Tech Inc. becomes the exclusive distributor for Yoshioka Seiko Co. porous chucks for Europe and North America July 20th, 2014

Carbodeon enables 20 percent increase in polymer thermal filler conductivity with 0.03 wt.% nanodiamond additive at a lower cost than with traditional fillers: Improved materials and processes enable nanodiamond cost reductions of up to 70 percent for electronics and LED app July 9th, 2014

'Nano-pixels' promise thin, flexible, high resolution displays July 9th, 2014

Projecting a Three-Dimensional Future: TAU researchers develop holography technology that could change the way we view the world July 9th, 2014

Govt.-Legislation/Regulation/Funding/Policy

NIST shows ultrasonically propelled nanorods spin dizzyingly fast July 22nd, 2014

Penn Study: Understanding Graphene’s Electrical Properties on an Atomic Level July 22nd, 2014

Oregon chemists eye improved thin films with metal substitution: Solution-based inorganic process could drive more efficient electronics and solar devices July 21st, 2014

More than glitter: Scientists explain how gold nanoparticles easily penetrate cells, making them useful for delivering drugs July 21st, 2014

Sensors

Tiny laser sensor heightens bomb detection sensitivity July 19th, 2014

Iranian Scientists Use Nanosensors to Achieve Best Limit for Early Cancer Diagnosis July 19th, 2014

Rice nanophotonics experts create powerful molecular sensor: Sensor amplifies optical signature of single molecules about 100 billion times July 15th, 2014

University of Illinois researchers demonstrate novel, tunable nanoantennas July 14th, 2014

Nanoelectronics

3-D nanostructure could benefit nanoelectronics, gas storage: Rice U. researchers predict functional advantages of 3-D boron nitride July 15th, 2014

IBM Announces $3 Billion Research Initiative to Tackle Chip Grand Challenges for Cloud and Big Data Systems: Scientists and engineers to push limits of silicon technology to 7 nanometers and below and create post-silicon future July 10th, 2014

Carbodeon enables 20 percent increase in polymer thermal filler conductivity with 0.03 wt.% nanodiamond additive at a lower cost than with traditional fillers: Improved materials and processes enable nanodiamond cost reductions of up to 70 percent for electronics and LED app July 9th, 2014

Nanotechnology that will impact the Security & Defense sectors to be discussed at NanoSD2014 conference July 8th, 2014

Discoveries

Researchers create vaccine for dust-mite allergies Main Page Content: Vaccine reduced lung inflammation to allergens in lab and animal tests July 22nd, 2014

NIST shows ultrasonically propelled nanorods spin dizzyingly fast July 22nd, 2014

Penn Study: Understanding Graphene’s Electrical Properties on an Atomic Level July 22nd, 2014

NUS scientists use low cost technique to improve properties and functions of nanomaterials: By 'drawing' micropatterns on nanomaterials using a focused laser beam, scientists could modify properties of nanomaterials for effective applications in photonic and optoelectric applicat July 22nd, 2014

Announcements

Nanometrics Announces Upcoming Investor Events July 22nd, 2014

Bruker Awarded Fourth PeakForce Tapping Patent: AFM Mode Uniquely Combines Highest Resolution Imaging and Material Property Mapping July 22nd, 2014

NIST shows ultrasonically propelled nanorods spin dizzyingly fast July 22nd, 2014

Penn Study: Understanding Graphene’s Electrical Properties on an Atomic Level July 22nd, 2014

Research partnerships

Penn Study: Understanding Graphene’s Electrical Properties on an Atomic Level July 22nd, 2014

More than glitter: Scientists explain how gold nanoparticles easily penetrate cells, making them useful for delivering drugs July 21st, 2014

Tiny laser sensor heightens bomb detection sensitivity July 19th, 2014

Labs characterize carbon for batteries: Rice, Lawrence Livermore scientists calculate materials’ potential for use as electrodes July 14th, 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