Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

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

Photonic chip guides single photons, even when there are bends in the road February 16th, 2018

Arrowhead Receives Regulatory Clearance to Begin Phase 1/2 Study of ARO-HBV for Treatment of Hepatitis B February 15th, 2018

Arrowhead Pharmaceuticals Receives Orphan Drug Designation for ARO-AAT February 15th, 2018

European & Korean Project To Demo World’s First 5G Platform During Winter Games February 15th, 2018

Display technology/LEDs/SS Lighting/OLEDs

Rutgers-Led Innovation Could Spur Faster, Cheaper, Nano-Based Manufacturing: Scalable and cost-effective manufacturing of thin film devices February 14th, 2018

Atomic Flaws Create Surprising, High-Efficiency UV LED Materials: Subtle surface defects increase UV light emission in greener, more cost-effective LED and catalyst materials February 8th, 2018

Liquid crystal molecules form nano rings: Quantized self-assembly enables design of materials with novel properties February 7th, 2018

Nanowire LED Innovator Aledia Announces €30 ($36M) Million Series-C Financing: Intel Capital Joins Existing Investors to Commercialize Certain Nanowire-LED Technologies for Mobile Displays January 29th, 2018

Govt.-Legislation/Regulation/Funding/Policy

Arrowhead Receives Regulatory Clearance to Begin Phase 1/2 Study of ARO-HBV for Treatment of Hepatitis B February 15th, 2018

Arrowhead Pharmaceuticals Receives Orphan Drug Designation for ARO-AAT February 15th, 2018

Rutgers-Led Innovation Could Spur Faster, Cheaper, Nano-Based Manufacturing: Scalable and cost-effective manufacturing of thin film devices February 14th, 2018

Understanding brain functions using upconversion nanoparticles: Researchers can now send light deep into the brain to study neural activities February 14th, 2018

Discoveries

Photonic chip guides single photons, even when there are bends in the road February 16th, 2018

'Living bandages': NUST MISIS scientists develop biocompatible anti-burn nanofibers February 15th, 2018

Rutgers-Led Innovation Could Spur Faster, Cheaper, Nano-Based Manufacturing: Scalable and cost-effective manufacturing of thin film devices February 14th, 2018

Understanding brain functions using upconversion nanoparticles: Researchers can now send light deep into the brain to study neural activities February 14th, 2018

Announcements

Photonic chip guides single photons, even when there are bends in the road February 16th, 2018

Arrowhead Receives Regulatory Clearance to Begin Phase 1/2 Study of ARO-HBV for Treatment of Hepatitis B February 15th, 2018

Arrowhead Pharmaceuticals Receives Orphan Drug Designation for ARO-AAT February 15th, 2018

European & Korean Project To Demo World’s First 5G Platform During Winter Games February 15th, 2018

Energy

Round-the-clock power from smart bowties February 5th, 2018

Silk fibers could be high-tech ‘natural metamaterials’ January 31st, 2018

A simple new approach to plastic solar cells: Osaka University researchers intelligently design new highly efficient organic solar cells based on amorphous electronic materials with potential for easy printing January 28th, 2018

Nature paper by Schlumberger researchers used photothermal based nanoscale IR spectroscopy to analyze heterogeneous process of petroleum generation January 23rd, 2018

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

Leti Chief Scientist Barbara De Salvo Will Help Kick Off ISSCC 2018 with Opening-Day Keynote: In Addition, Leti Scientists Will Present and Demo New Technology for Piezoelectric Energy Harvesting February 8th, 2018

Round-the-clock power from smart bowties February 5th, 2018

NTU scientists create customizable, fabric-like power source for wearable electronics January 30th, 2018

Ultra-thin memory storage device paves way for more powerful computing January 17th, 2018

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