Featured Research

from universities, journals, and other organizations

Nanotubes Grown Straight In Large Numbers

Date:
April 24, 2008
Source:
Duke University
Summary:
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.

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."

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.


Story Source:

The above story is based on materials provided by Duke University. Note: Materials may be edited for content and length.


Cite This Page:

Duke University. "Nanotubes Grown Straight In Large Numbers." ScienceDaily. ScienceDaily, 24 April 2008. <www.sciencedaily.com/releases/2008/04/080423124533.htm>.
Duke University. (2008, April 24). Nanotubes Grown Straight In Large Numbers. ScienceDaily. Retrieved July 25, 2014 from www.sciencedaily.com/releases/2008/04/080423124533.htm
Duke University. "Nanotubes Grown Straight In Large Numbers." ScienceDaily. www.sciencedaily.com/releases/2008/04/080423124533.htm (accessed July 25, 2014).

Share This




More Matter & Energy News

Friday, July 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

TSA Administrator on Politics and Flight Bans

TSA Administrator on Politics and Flight Bans

AP (July 24, 2014) TSA administrator, John Pistole's took part in the Aspen Security Forum 2014, where he answered questions on lifting of the ban on flights into Israel's Tel Aviv airport and whether politics played a role in lifting the ban. (July 24) Video provided by AP
Powered by NewsLook.com
Creative Makeovers for Ugly Cellphone Towers

Creative Makeovers for Ugly Cellphone Towers

AP (July 24, 2014) Mobile phone companies and communities across the country are going to new lengths to disguise those unsightly cellphone towers. From a church bell tower to a flagpole, even a pencil, some towers are trying to make a point. (July 24) Video provided by AP
Powered by NewsLook.com
Algonquin Power Goes Activist on Its Target Gas Natural

Algonquin Power Goes Activist on Its Target Gas Natural

TheStreet (July 23, 2014) When The Deal's Amanda Levin exclusively reported that Gas Natural had been talking to potential suitors, the Ohio company responded with a flat denial, claiming its board had not talked to anyone about a possible sale. Lo and behold, Canadian utility Algonquin Power and Utilities not only had approached the company, but it did it three times. Its last offer was for $13 per share as Gas Natural's was trading at a 60-day moving average of about $12.50 per share. Now Algonquin, which has a 4.9% stake in Gas Natural, has taken its case to shareholders, calling on them to back its proposals or, possibly, a change in the target's board. Video provided by TheStreet
Powered by NewsLook.com
Robot Parking Valet Creates Stress-Free Travel

Robot Parking Valet Creates Stress-Free Travel

AP (July 23, 2014) 'Ray' the robotic parking valet at Dusseldorf Airport in Germany lets travelers to avoid the hassle of finding a parking spot before heading to the check-in desk. (July 23) Video provided by AP
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