Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

'High Q' NIST nanowires may be practical oscillators

30.11.2007
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.

Laura Ost | EurekAlert!
Further information:
http://www.nist.gov

More articles from Physics and Astronomy:

nachricht On Mars, sands shift to a different drum
24.05.2019 | University of Arizona

nachricht New Boost for ToCoTronics
23.05.2019 | Julius-Maximilians-Universität Würzburg

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New studies increase confidence in NASA's measure of Earth's temperature

A new assessment of NASA's record of global temperatures revealed that the agency's estimate of Earth's long-term temperature rise in recent decades is accurate to within less than a tenth of a degree Fahrenheit, providing confidence that past and future research is correctly capturing rising surface temperatures.

The most complete assessment ever of statistical uncertainty within the GISS Surface Temperature Analysis (GISTEMP) data product shows that the annual values...

Im Focus: The geometry of an electron determined for the first time

Physicists at the University of Basel are able to show for the first time how a single electron looks in an artificial atom. A newly developed method enables them to show the probability of an electron being present in a space. This allows improved control of electron spins, which could serve as the smallest information unit in a future quantum computer. The experiments were published in Physical Review Letters and the related theory in Physical Review B.

The spin of an electron is a promising candidate for use as the smallest information unit (qubit) of a quantum computer. Controlling and switching this spin or...

Im Focus: Self-repairing batteries

UTokyo engineers develop a way to create high-capacity long-life batteries

Engineers at the University of Tokyo continually pioneer new ways to improve battery technology. Professor Atsuo Yamada and his team recently developed a...

Im Focus: Quantum Cloud Computing with Self-Check

With a quantum coprocessor in the cloud, physicists from Innsbruck, Austria, open the door to the simulation of previously unsolvable problems in chemistry, materials research or high-energy physics. The research groups led by Rainer Blatt and Peter Zoller report in the journal Nature how they simulated particle physics phenomena on 20 quantum bits and how the quantum simulator self-verified the result for the first time.

Many scientists are currently working on investigating how quantum advantage can be exploited on hardware already available today. Three years ago, physicists...

Im Focus: Accelerating quantum technologies with materials processing at the atomic scale

'Quantum technologies' utilise the unique phenomena of quantum superposition and entanglement to encode and process information, with potentially profound benefits to a wide range of information technologies from communications to sensing and computing.

However a major challenge in developing these technologies is that the quantum phenomena are very fragile, and only a handful of physical systems have been...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

SEMANTiCS 2019 brings together industry leaders and data scientists in Karlsruhe

29.04.2019 | Event News

Revered mathematicians and computer scientists converge with 200 young researchers in Heidelberg!

17.04.2019 | Event News

First dust conference in the Central Asian part of the earth’s dust belt

15.04.2019 | Event News

 
Latest News

New system by TU Graz automatically recognises pedestrians’ intent to cross the road

27.05.2019 | Information Technology

On Mars, sands shift to a different drum

24.05.2019 | Physics and Astronomy

Piedmont Atlanta first in Georgia to offer new minimally invasive treatment for emphysema

24.05.2019 | Medical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>