Thursday, December 27, 2007

US Patent 7311889 - Laminated trench for CNT growth

One of the difficulty in carbon nanotube production is that there are many flavors of nanotubes based on the chirality, orientation, and diameter and it is difficult to mass produce nanotubes of a specific type without producing other types that need to be sorted from the desired type. This patent from Fujitsu teaches an interesting solution based on a CVD process that uses a lamination of catalytic layers with a V-groove etched therein as the template for nanotube growth with well controlled diameter and directionality. Claim 18 reads:

18. A carbon nanotube production process comprising a step of preparing a substrate which is inclined in one direction from a specific symmetrical crystal orientation and vapor depositing a metal catalyst along the atomic steps appearing on the surface of the substrate, and a step of growing the carbon nanotubes by chemical vapor deposition (CVD) using the metal catalyst as nuclei.