Navigation Links
Nanotubes grown straight in large numbers
Date:4/23/2008

DURHAM, N.C. -- 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.


'/>"/>

Contact: Monte Basgall
monte.basgall@duke.edu
919-681-8057
Duke University
Source:Eurekalert

Related biology technology :

1. Carbon nanotubes made into conductive, flexible stained glass
2. The future of computing -- carbon nanotubes and superconductors to replace the silicon chip
3. Carbon nanotubes outperform copper nanowires as interconnects
4. Nanotubes go with the flow
5. Carbon nanotubes to be replaced by MoSIx nanowires in high-tech devices says new study
6. Improved wettability of carbon nanotubes opens the door to new possibilities
7. Understanding of actuator properties of carbon nanotubes bring micro machines closer
8. The sensitive side of carbon nanotubes: Creating powerful pressure sensors
9. Nanotube forests grown on silicon chips for future computers, electronics
10. The American Fertility Association Brings Fertility Education to San Francisco or Parent Hopefuls - Straight and Gay
11. The pitter patter of little feet ... climbing straight up a wall
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:5/23/2016)... Springs, North Carolina (PRWEB) , ... May 23, ... ... process automation and building management solutions and services based in Aurora, Ohio, has ... decade of established business in the Research Triangle Park area, this new location ...
(Date:5/22/2016)... ... May 22, 2016 , ... Doctors in Rome say ... the asbestos cancer, malignant mesothelioma. Surviving Mesothelioma has just posted an article on the ... University of Rome’s Department of Clinical Sciences and Translational Medicine evaluated more than 150 ...
(Date:5/20/2016)... ... May 20, 2016 , ... Kablooe Design, a leading provider of product ... official 25th anniversary of the business. “We have worked hard to build long-term relationships,” ... for the privilege and honor of serving their product design and development needs through ...
(Date:5/20/2016)... ... ... The recent recall by Costco and Trader Joes of 47 million pounds of ... demonstrates the need for faster and more cost effective bio-threat detection to ensure food ... , PathSensor’s latest solution uses a biosensor technology called CANARY®. CANARY®, an ...
Breaking Biology Technology:
(Date:3/10/2016)... 2016 --> ... "Identity and Access Management Market by Component (Provisioning, Directory ... by Organization Size, by Deployment, by Vertical, and by ... The market is estimated to grow from USD 7.20 ... at a Compound Annual Growth Rate (CAGR) of 12.2% ...
(Date:3/9/2016)... March 9, 2016 Nigeria ... that more than 23,000 public service employees either did ... receiving their salary unlawfully.    --> ... identified that more than 23,000 public service employees either ... been receiving their salary unlawfully.    --> ...
(Date:3/3/2016)... -- FlexTech, a SEMI Strategic Association Partner, awarded five FLEXI ... Leadership in Education, and, in a category new this ... year of the FLEXI Awards and the winners join ... past years . Judging was done on a set ... by a panel of non-affiliated, independent, industry experts. ...
Breaking Biology News(10 mins):