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.
The 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.
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. "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," he said.
In 2000, a research team became the first to make long and aligned nanotubes grow on surfaces, though not in a sufficiently parallel and straight way. They also vied with other groups in growing nanotubes to record lengths.
Using copper as their growth catalyst and gasified alcohol to supply carbon, the Duke researchers now 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.
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.
He and collaborators are now exhaustively testing their nanotubes to see how many have the right architectures to serve as semiconductors.
COMPAMED.de; Source: Duke University