Nanobridges Show Way to Nano Mass Production
They look like an elegant row of columns, tiny enough for atomic-scale hide-and-seek, but these colonnades represent a new way to bring nanotechnology into mass production.
Nanotechnology, the ability to create and work with structures and materials on an atomic scale, holds the promise of extreme miniaturization for electronics, chemical sensors and medical devices. But while researchers have created tiny silicon wires and connected them together one at a time, these methods cannot easily be scaled up.
"It takes weeks to make one or two, and you end up with different sizes and characteristics," said M. Saif Islam, assistant professor of electrical and computer engineering, who joined UC Davis from Hewlett-Packard Laboratories in 2004.
Like handmade shoes, every manually assembled nanostructure comes out slightly different. Engineers would rather build devices the way cars or computers are built, with every item as consistent as possible.
While working at the Quantum Science Research group of Hewlett-Packard Laboratories, Islam and colleagues came up with a new approach. Silicon wafers used for building microcircuits are usually polished at one specific angle to the atomic planes of silicon. Instead, the group used a wafer that was polished at a different angle, changing the orientation of silicon atomic planes to the surface. Using a chemical vapor deposition technique, they could then grow identical, perpendicular columns of silicon.
The researchers have used this method to grow "nanobridges" across a gap between two vertical silicon electrodes. The nanobridges are strong, chemically stable and show better electrical properties than previous approaches, Islam said. They could be used for nanosized transistors, chemical sensors or lasers.
Taking the approach a step further, Islam and his colleagues at Hewlett-Packard made sandwiches of silicon and insulator and partly etched away the top layer to create awning-shaped structures of silicon supported by insulator. Silicon columns grown under the awnings form miniature colonnades.
The method allows engineers to combine nanowires of precise length with other silicon structures such as integrated circuits, he said.
At UC Davis, Islam plans to continue work on converting the technology into practical devices. The "nanobridge" technique was reported most recently in the March 2005 issue of the journal Applied Physics Part A. The nanocolonnade work was presented April 1 at the spring meeting of the Materials Research Society in San Francisco.
Andy Fell | EurekAlert!
The most recent press releases about innovation >>>
Die letzten 5 Focus-News des innovations-reports im Überblick:
Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.
As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...
Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.
Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...
For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.
While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...
An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.
The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...
A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.
Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...