US Patent 7834530 - Nanotube bundle field emitters

http://www.freepatentsonline.com/7834530.html

Carbon nanotubes have been shown to produce superior electron emission at low electric field strength than other materials but when formed in high density arrays a field screening effect occurs that can diminish the emission density. This patent from CalTech teaches forming an optimized high field emission geometry based upon ordered arrays of nanotube bundles. Claim 1 reads:

1. A high density field emitter comprising:

a plurality of nanotube bundles disposed on a substrate each of said bundles comprising a plurality of individual nanotubes and being characterized by a nanotube bundle dimension defining the spatial cross-section of the individual nanotube bundles,

said bundles being arranged on said substrate in an ordered array characterized by an array dimension defining the edge-to-edge spacing between each said nanotube bundle,

wherein the array dimension is about 5.0 μm and a ratio of the bundle dimension to the array dimension ranges from about 0.2:100 to about 5:2.