Nanotech promises super-fast transistors

Carbon nanotubes can act as semiconductors

US researchers have published details of a technique that allows the mass production of long straight cylinders only a few atoms thick.

The breakthrough removes a major roadblock in the pursuit of nano-scale electronics, according to the Duke University chemists.

Associate chemistry professor Jie Liu, who led the research, explained that carbon nanotubes can act as semiconductors and could further scale-down circuitry to features measuring just billionths of a metre.

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 nano-engineers to bundle them onto multiple ultra-tiny chips that could operate with enough power and speed for nano-processing.

"It is quite an exciting development," said Liu, who has received a patent on the process.

"Compared with other research, 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 co-authors, postdoctoral fellow Lei Ding and graduate student Dongning Yuan, describe their work in the Journal of the American Chemical Society.

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

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 and his collaborators are now "exhaustively testing" the nanotubes to see how many have the right architecture to serve as semiconductors.