The major stumbling block to the use of carbon nanotubes in electronics has been the inability to produce carbon nanotubes that are chemically pure enough to function in electronics. University of Illinois at Urbana Champaign professor John Rogers and colleagues have developed a simple and cheap method of producing carbon nanotubes that are 99.999 percent pure. This level of purity makes the nanotubes functionally efficient for higher speed electronics.
The researchers developed a method that makes high purity sheets of nanotubes possible and can allow the extraction of a single microscopic nanotube from an array of nanotubes. The method deposits an organic layer on top of a sheet of nanotubes that is attached to a metallic layer. Applying an electric current to the combination of layers identifies the nanotubes that are contaminated by metals. Nanotubes that contain metal are not semiconducting. The point of using carbon nanotubes is the enhanced semiconducting capacity of carbon nanotubes.
The nanotubes that are contaminated with metal can be etched out of the array and the organic top coat can be removed with a chemical bath leaving pure carbon nanotubes. The method is inexpensive and scaleable to industrial sized capacities. The researchers proved their method works by constructing an array of transistors from the purified carbon nanotubes. The high speed transistors functioned as expected. This development is the last step needed in making carbon nanotubes a realistic replacement for silicon in all electronic devices. The added speed of transmission is the driving concept behind carbon nanotubes.
