US Patent 7326605 - Conversion of metallic CNTs to semiconducting CNTs using hydrogen doping

http://www.freepatentsonline.com/7326605.html

Single wall carbon nanotubes have metallic or semiconducting properties depending on the diameter of the tubes and the arrangement of the carbon lattice with respect to the length of the tubes. Several techniques such as DNA wrapping have been proposed to sort between these two types. This patent from Samsung teaches an alternative method using hydrogen to convert metallic carbon nanotubes to a semiconducting material. Claim 1 reads:

1. A method for fabricating semiconductor carbon nanotubes, the method comprising: heating carbon nanotubes in a vacuum; dissociating hydrogen molecules in hydrogen gas into hydrogen atoms; and exposing the carbon nanotubes to the hydrogen gas to form chemical bonds between carbon atoms of the carbon nanotubes and the hydrogen atoms, wherein the chemical bonds between the carbon and hydrogen atoms are sp3 hybrid bonds.