Onderzoekers van IBM hebben bekendgemaakt een nieuw procédé te hebben ontwikkeld om carbon nanotubes mee te vervaardigen, schrijft C|Net. De nieuwe methode behelst de toepassing van silicium in plaats van metaal, als catalysator in het nanotube-fabricageproces. Het procédé wordt uit de doeken gedaan in de oktobereditie van het blad Nanoletters. De nieuwe methode zou de yields van de productie van enkelwandige nanotubes kunnen verbeteren. Enkelwandige nanotubes behoren tot de meestbelovende terreinen op het gebied van chipcircuits, aldus Phaedon Avouris, manager van nanoscale science bij IBM:
"We have shown that there are ways of making single-walled nanotubes without the use of metals," Avouris said. Carbon nanotubes represent one of the two leading candidates to replace wires inside chips and other components in a decade. Not only do these structures conduct electricity well, they are incredibly small, which should allow manufacturers to squeeze billions of transistors onto a single chip. For now, nanotubes can only be manufactured in small numbers inside labs. Affordable, mass-marketing techniques remain years away.
Under the metal catalyst method, nickel, iron or cobalt is heated with carbon atoms until the metal melts. Single-walled nanotubes then form on the surface of the liquid metal. Unfortunately, metal particles become attached to the nanotubes, which magnetizes them and makes them unusable as transistors. "For every nanotube there is a particle of metal," Avouris said. "Removing the metal involves boiling them in nitric acid, which damages the nanotube."
In IBM's technique, the nanotubes are not damaged. Researchers take a crystal formed from layers of silicon and carbon and heat it to 1,650 degrees centigrade. The silicon evaporates, leaving an exposed layer of carbon. Because the carbon formerly was bonded to the silicon, it is freed to bond with another material. In this case, it bonds with itself, curling up to form a tube.