TROY, N.Y. Researchers at Rensselaer Polytechnic Institute have demonstrated the world's longest carbon nanotubes. Using chemical vapor deposition (CVD), the standard process for semiconductor fabrication, researchers discovered that adding hydrogen and sulfur compounds produced high yields of wires as long as eight inches.
According to Rensselaer associate professor Pulickel Ajayan, this marked the first time a process has been shown to grow nanotubes long enough to serve as bus interconnects across or even between chips. Ajayan was assisted by his graduate student, Bingqing Wei from Tsinghua University in Beijing.
Since their discovery in 1991, carbon nanotubes have held the promise of supporting near-superconducting speeds at room temperature. Carbon nanotubes also exhibit quantum effects when doped with impurities. Their first application will probably be as the channel in tiny field-effect transistors.
Unfortunately, other attempts to use CVD to grow long nanotubes have resulted in a tangled mess, since the tiny structures tend to clump together in a manner similar to the way protein strands fold.
Ajayan's innovation was to add a sulfur compound in the presence of hydrogen, resulting in untangled nanowires as long as eight inches. According to Wei, the process could be adopted universally as an easier alternative to create nanotube material in general.