Featured Research

from universities, journals, and other organizations

'High Q' NIST Nanowires May Be Practical Oscillators

Date:
December 4, 2007
Source:
National Institute of Standards and Technology
Summary:
Nanowires grown at NIST have a mechanical 'quality factor' at least 10 times higher than reported values for other nanoscale devices such as carbon nanotubes, and comparable to that of commercial quartz crystals. Suggesting possible future uses as oscillators in nanoelectromechanical systems for nanosensors and communications devices.

Electron micrograph of a NIST-grown nanowire with a high "quality factor" vibrating more than 1 million times per second. At lower right, a stationary nanowire shows the typical hexagonal shape of the gallium nitride structures.
Credit: S. Tanner, CU/JILA

Nanowires grown at the National Institute of Standards and Technology (NIST) have a mechanical "quality factor" at least 10 times higher than reported values for other nanoscale devices such as carbon nanotubes, and comparable to that of commercial quartz crystals. Because a high Q factor indicates a capacity for stable vibrations, the nanowires might be used as oscillators in nano-electromechanical systems for future nano-sensors and communications devices.

"We think the most interesting thing about these wires is the very high quality factor observed for such a small object," says NIST researcher and co-author Kris Bertness, who grew the nanowires.

NIST has developed a unique way of growing hexagonal gallium nitride (GaN) nanowires featuring low defect density and high luminescence intensity. In a new paper*, researchers at NIST and the University of Colorado at Boulder report high Q factors in wires that are 30 to 500 nanometers in diameter and 5 to 20 micrometers long, vibrating between 400,000 and 2.8 million times per second. (For comparison, the quartz crystals used in watches usually vibrate about 32,000 times a second.) The nanowires vibrated when placed on a piezoelectric device stimulated by an electrical signal. The nanowires also oscillated when excited directly by an electron beam, apparently due to the GaN material's intrinsic piezoelectric ability to covert voltage to mechanical force.

Q measures the damping of oscillations in a mechanical system as a function of frequency--the higher its Q, the longer a bell rings after being struck. Ordinarily, Q factors of mechanical resonators tend to drop as their diameters shrink. But GaN nanowires have a number of properties that may boost their Q and make them suitable as practical oscillators. They have extremely flat and smooth surfaces (irregularities have reduced performance in other oscillators.) GaN also has a resonant frequency similar to silicon (commonly used in microelectronics) but is less susceptible to some sources of "noise." Finally, GaN has high heat capacity and thermal conductivity, reducing sensitivity to temperature fluctuations. Another practical advantage is that NIST's GaN nanowires are grown on silicon, making them compatible with existing microelectronics processing methods.

To measure the resonance properties of the nanowires, researchers observed clumps of nanowires using a scanning electron microscope. As the frequency of the applied signal was varied across a range, the nanowires seen in micrographs appear to blur or fan out at or near the resonance frequency. For the nanowire shown in the image, the Q value (about 38,000) is at least 10 times higher than previously reported values for other GaN nanowires, carbon nanotubes, and single-crystal silicon microstructures of similar surface-to-volume ratio. The researchers have measured Q values of more than 1 million in resonating GaN nanowires using feedback (like continuous striking of a bell to keep it ringing), as would occur in a real device.

* S.M. Tanner, J.M. Gray, C.T. Rogers, K.A. Bertness and N.A. Sanford. 2007. High-Q GaN Nanowire Resonators and Oscillators. Applied Physics Letters. 91, 203117 (2007).


Story Source:

The above story is based on materials provided by National Institute of Standards and Technology. Note: Materials may be edited for content and length.


Cite This Page:

National Institute of Standards and Technology. "'High Q' NIST Nanowires May Be Practical Oscillators." ScienceDaily. ScienceDaily, 4 December 2007. <www.sciencedaily.com/releases/2007/11/071127153342.htm>.
National Institute of Standards and Technology. (2007, December 4). 'High Q' NIST Nanowires May Be Practical Oscillators. ScienceDaily. Retrieved April 23, 2014 from www.sciencedaily.com/releases/2007/11/071127153342.htm
National Institute of Standards and Technology. "'High Q' NIST Nanowires May Be Practical Oscillators." ScienceDaily. www.sciencedaily.com/releases/2007/11/071127153342.htm (accessed April 23, 2014).

Share This



More Matter & Energy News

Wednesday, April 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Is North Korea Planning Nuclear Test #4?

Is North Korea Planning Nuclear Test #4?

Newsy (Apr. 22, 2014) South Korean officials say North Korea is preparing to conduct another nuclear test, but is Pyongyang just bluffing this time? Video provided by Newsy
Powered by NewsLook.com
China Falls for 4x4s at Beijing Auto Show

China Falls for 4x4s at Beijing Auto Show

AFP (Apr. 22, 2014) The urban 4x4 is the latest must-have for Chinese drivers, whose conversion to the cult of the SUV is the talking point of this year's Beijing auto show. Duration: 00:40 Video provided by AFP
Powered by NewsLook.com
Lytro Introduces 'Illum,' A Professional Light-Field Camera

Lytro Introduces 'Illum,' A Professional Light-Field Camera

Newsy (Apr. 22, 2014) The light-field photography engineers at Lytro unveiled their next innovation: a professional DSLR-like camera called "Illum." Video provided by Newsy
Powered by NewsLook.com
3 Reasons Why Harley Davidson Is Selling Tons of Epic Hogs

3 Reasons Why Harley Davidson Is Selling Tons of Epic Hogs

TheStreet (Apr. 22, 2014) Sales of motorcycles have continued to ride back from the depths of hell known as the Great Recession. Excluding scooters, sales of motorcycles increased 3% in 2013. In units, however, at 465,000 sold last year, the total remained about 50% below the peak hit in 2007. Industry leader Harley Davidson’s shareholders have benefited both by the industry recovery and positive headlines emanating from the company. Belus Capital Advisors CEO Brian Sozzi takes you beyond the headlines of the motorcycle maker. Video provided by TheStreet
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins