Nanotechnology Now







Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > Growing Nanowires Horizontally Yields New Benefit:: 'Nano-LEDs'

Transmission electron microscope image of “nano LEDs” emitting light.

Credit: NIST
Transmission electron microscope image of “nano LEDs” emitting light.

Credit: NIST

Abstract:
While refining their novel method for making nanoscale wires, chemists at the National Institute of Standards and Technology (NIST) discovered an unexpected bonus—a new way to create nanowires that produce light similar to that from light-emitting diodes (LEDs). These "nano-LEDs" may one day have their light-emission abilities put to work serving miniature devices such as nanogenerators or lab-on-a-chip systems.

Growing Nanowires Horizontally Yields New Benefit:: 'Nano-LEDs'

Gaithersburg, MD | Posted on September 29th, 2010

Nanowires typically are "grown" by the controlled deposition of molecules—zinc oxide, for example—from a gas onto a base material, a process called chemical vapor deposition (CVD). Most CVD techniques form nanowires that rise vertically from the surface like brush bristles. Because the wire only contacts the substrate at one end, it tends not to share characteristics with the substrate material—a less-than-preferred trait because the exact composition of the nanowire will then be hard to define. Vertical growth also produces a dense forest of nanowires, making it difficult to find and re-position individual wires of superior quality. To remedy these shortcomings, NIST chemists Babak Nikoobakht and Andrew Herzing developed a "surface-directed" method for growing nanowires horizontally across the substrate (see "NIST Demos Industrial-Grade Nanowire Device Fabrication" NIST Tech Beat, Oct. 25, 2007, at www.nist.gov/public_affairs/techbeat/tb2007_1025.htm#nanowire).

Like many vertical growth CVD methods, the NIST fabrication technique uses gold as a catalyst for crystal formation. The difference is that the gold deposited in the NIST method is heated to 900 degrees Celsius (1,652 degrees Fahrenheit), converting it to a nanoparticle that serves as growth site and medium for the crystallization of zinc oxide molecules. As the zinc oxide nanocrystal grows, it pushes the gold nanoparticle along the surface of the substrate (in this experiment, gallium nitride) to form a nanowire that grows horizontally across the substrate and so exhibits properties strongly influenced by its base material.

In recent work published in ACS Nano,* Nikoobakht and Herzing increased the thickness of the gold catalyst nanoparticle from less than 8 nanometers to approximately 20 nanometers. The change resulted in nanowires that grew a secondary structure, a shark-like "dorsal fin" (referred to as a "nanowall") where the zinc oxide portion is electron-rich and the gallium nitride portion is electron-poor. The interface between these two materials—known as a p-n heterojunction—allows electrons to flow across it when the nanowire-nanowall combination was charged with electricity. In turn, the movement of electrons produced light and led the researchers to dub it a "nano LED."

Unlike previous techniques for producing heterojunctions, the NIST "surface-directed" fabrication method makes it easy to locate individual heterojunctions on the surface. This feature is especially useful when a large number of heterojunctions must be grouped in an array so that they can be electrically charged as a light-emitting unit.

Transmission electron microscope (TEM) examination of the zinc oxide-gallium nitride nanowires and nanowalls revealed few structural defects in the nanowires and very distinct p-n heterojunctions in the nanowalls, both affirmations of the effectiveness of the NIST "surface directed" fabrication method.

Nikoobakht and Herzing hope to improve the nano LEDs in future experiments using better geometry and material designs, and then apply them in the development of light sources and detectors useful in photonic devices or lab-on-a-chip platforms.

* B. Nikkoobakht and A. Herzing. Formation of planar arrays of one-dimensional p-n heterojunctions using surface-directed growth of nanowires and nanowalls. ACS Nano. Published online Sept. 15, 2010.

####

About NIST
The National Institute of Standards and Technology (NIST) is an agency of the U.S. Commerce Department.

For more information, please click here

Contacts:
Michael E. Newman
301-975-3025

Copyright © NIST

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

Quantum teleportation on a chip: A significant step towards ultra-high speed quantum computers April 1st, 2015

So, near and yet so far: Stable HGNs for Raman April 1st, 2015

Two-dimensional dirac materials: Structure, properties, and rarity April 1st, 2015

3-D neural structure guided with biocompatible nanofiber scaffolds and hydrogels April 1st, 2015

Display technology/LEDs/SS Lighting/OLEDs

Roll up your screen and stow it away? Tel Aviv University researchers develop molecular backbone of super-slim, bendable digital displays March 30th, 2015

Solving molybdenum disulfide's 'thin' problem: Research team increases material's light emission by twelve times March 29th, 2015

Haydale Announce Dedicated Graphene Inks Manufacturing Capability March 25th, 2015

Caltech scientists develop cool process to make better graphene March 18th, 2015

Govt.-Legislation/Regulation/Funding/Policy

Mind the gap: Nanoscale speed bump could regulate plasmons for high-speed data flow April 1st, 2015

Cooling massive objects to the quantum ground state April 1st, 2015

Two-dimensional dirac materials: Structure, properties, and rarity April 1st, 2015

Rutgers, NIST physicists report technology with potential for sub-micron optical switches March 31st, 2015

Discoveries

Mind the gap: Nanoscale speed bump could regulate plasmons for high-speed data flow April 1st, 2015

Cooling massive objects to the quantum ground state April 1st, 2015

A novel way to apply drugs to dental plaque Nanoparticles release drugs to reduce tooth decay April 1st, 2015

Quantum teleportation on a chip: A significant step towards ultra-high speed quantum computers April 1st, 2015

Announcements

Quantum teleportation on a chip: A significant step towards ultra-high speed quantum computers April 1st, 2015

So, near and yet so far: Stable HGNs for Raman April 1st, 2015

Two-dimensional dirac materials: Structure, properties, and rarity April 1st, 2015

3-D neural structure guided with biocompatible nanofiber scaffolds and hydrogels April 1st, 2015

Energy

Wrapping carbon nanotubes in polymers enhances their performance: Scientists at Japan's Kyushu University say polymer-wrapped carbon nanotubes hold much promise in biotechnology and energy applications March 30th, 2015

Solving molybdenum disulfide's 'thin' problem: Research team increases material's light emission by twelve times March 29th, 2015

SUNY Poly & M+W Make Major Announcement: Major Expansion To Include M+W Owned Gehrlicher Solar America Corporation That Will Create up to 400 Jobs to Develop Solar Power Plants at SUNY Poly Sites Across New York State March 26th, 2015

Hong Kong Investors Bullish on Dais Analytic Invest $5.75M, Provide $60M Contract, and Create New Joint Venture Company March 26th, 2015

Battery Technology/Capacitors/Generators/Piezoelectrics/Thermoelectrics/Energy storage

Chemists make new silicon-based nanomaterials March 27th, 2015

New processing technology converts packing peanuts to battery components March 22nd, 2015

NC State researchers create 'nanofiber gusher': Report method of fabricating larger amounts of nanofibers in liquid March 19th, 2015

Drexel Univ. materials research could unlock potential of lithium-sulfur batteries March 17th, 2015

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 1999-2015 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE