Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Nanotubes grown straight in large numbers

25.04.2008
Duke University chemists have found a way to grow long, straight cylinders only a few atoms thick in very large numbers, removing a major roadblock in the pursuit of nano-scale electronics.

These single-walled carbon nanotubes also follow parallel paths as they grow so they don't cross each other to potentially impede electronic performance, said Duke associate chemistry professor Jie Liu, who leads the research. Carbon nanotubes can act as semiconductors and could thus further scale-down circuitry to features measuring only billionths of a meter.

Liu's team directed swarms of nanotubes to extend in the same direction by using the crystal structure of a quartz surface as a template. The availability of forests of identical nanotubes would allow future nanoengineers to bundle them onto multiple ultra-tiny chips that could operate with enough power and speed for nanoprocessing.

"It's quite an exciting development," said Liu, who has received a patent on the process. "Compared with what other people have done, we have reached a higher density of nanotubes. Wherever you look through the microscope there are nanotubes. And they are much better aligned and grow very straight."

... more about:
»Carbon »Liu »Nanotubes »Semiconductor »Surface »catalyst »quartz

Liu and two coauthors, postdoctoral fellow Lei Ding and graduate student Dongning Yuan, described their accomplishment April 16 in the Journal of the American Chemical Society (JACS). Ding was the study's first author. Their research was funded by the United States Naval Research Laboratory and by Duke.

Nanotubes have been a focus of research since the 1990s because of their exceptional lightness and strength and their potential to function in a new kind of electronics as either semiconductors or metals -- depending on their individual architectures.

Sized so small they can be viewed only with scanning electron or atomic force microscopes, carbon nanotubes could usher the electronics industry into an even-smaller scale of miniaturization if researchers can leap some fabrication barriers.

"This would break a logjam for reproducing enough of them in identical form to build into working devices," Liu said of his group's new innovation. "With our technique, their densities are high enough over a large area. And every device would be quite the same, even if thousands or a million of them were made," Liu said.

Researchers have for some time been able to coax nanotubes into growing and extending themselves when primed by a catalyst and provided with a continuous source of carbon delivered in a gas.

But, until now, they have been unable to make them grow straight, long and dense enough in a large enough area to be practical for carrying current on the surfaces of semiconducting wafers, Liu said.

Researchers have also been struggling to control growing nanotubes' tendencies to bend and overlap each other as they extend. Such overlaps would impede a future nanocircuit's performance at high operating speeds, he added.

In 2000, a Liu-led research team at Duke became the first to make long and aligned nanotubes grow on surfaces, though not in a sufficiently parallel and straight way, he said. He has also vied with other groups in growing nanotubes to record lengths.

Recently, other scientific groups developed a way to grow perfectly aligned nanotubes along continuous-and-unbroken "single crystal" surfaces of quartz or sapphire.

One team using that method reported making as many as 10 nanotubes grow within the space of a single micron -- one millionth of a meter -- using iron as a catalyst. They also observed areas with nanotubes as dense as 50 per micron. But such numbers at that density are still "low and not uniform enough for many useful electronic applications," Liu said.

In the new JACS report, Liu's group reports improving on that performance by modifying the method.

Using copper as their growth catalyst and gasified alcohol to supply carbon, the Duke researchers found that their nanotubes all extended in the same direction, following parallel paths determined by the crystalline orientation of "stable temperature" (ST)-cut quartz wafers used in electronic applications. "They're like a trains running on tracks that are all very straight," Liu said.

By applying computer chip fabrication-style masks to confine uniform coatings of catalyst within very narrow lines along those crystal orientations, Liu's group was able to keep an unprecedented number of nanotubes growing in parallel, without crossing paths.

"To the best of our knowledge, it is the highest density of aligned, single-wall nanotubes reported," the researchers wrote in JACS.

Once formed on ST-cut quartz, the aligned swarms of nanotubes can be transferred onto the less-expensive semiconductor wafers normally used in computer chips, Liu said. He and collaborators are now exhaustively testing their nanotubes to see how many have the right architectures to serve as semiconductors.

Monte Basgall | EurekAlert!
Further information:
http://www.duke.edu

Further reports about: Carbon Liu Nanotubes Semiconductor Surface catalyst quartz

More articles from Life Sciences:

nachricht Researchers identify potentially druggable mutant p53 proteins that promote cancer growth
09.12.2016 | Cold Spring Harbor Laboratory

nachricht Plant-based substance boosts eyelash growth
09.12.2016 | Fraunhofer-Institut für Angewandte Polymerforschung IAP

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Electron highway inside crystal

Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.

Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Researchers identify potentially druggable mutant p53 proteins that promote cancer growth

09.12.2016 | Life Sciences

Scientists produce a new roadmap for guiding development & conservation in the Amazon

09.12.2016 | Ecology, The Environment and Conservation

Satellites, airport visibility readings shed light on troops' exposure to air pollution

09.12.2016 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>