Surry University in the UK claims that they have created the first machine for commericial production of carbon nanotubes grown at low temperature. Evidently this machine will make better semiconductors than nanotubes grown at high temperature because existing silicon can be incorporated. I'm not sure if the silicon is being grown directly with the carbon in these applications, or if one is being added to the other at a later stage in production. Either way, silicon couldn't be used previously due to the high temperatures of the nanotube growth process.