US Patent 7632762 - Semiconductor nanotube device fabrication

http://www.freepatentsonline.com/7632762.html

Since at least 2001 the use of high current has been used as in a method of burning off "metallic" carbon nanotubes and leaving semiconductor carbon nanotubes. This patent from Foster-Miller teaches a similar method in which a ramped voltage is used to manufacture semiconductor nanotube devices. Claim 1 reads:

1. A method of forming a semiconductor device, comprising the steps of:

providing a substrate comprising two electrodes wherein the two electrodes are connected to a power supply;

providing a solvent comprising a plurality of semiconducting carbon nanotubes and a plurality of metallic carbon nanotubes;

submersing the substrate in the solvent wherein the plurality of semiconducting carbon nanotubes and plurality of metallic carbon nanotubes form a carbon nanotube bundle disposed between the two electrodes; and

ramping a bias voltage across the two electrodes wherein the ramping of the bias voltage removes the plurality of metallic carbon nanotubes in an amount sufficient to form the semiconducting device.