US Patent 7176478 - Nanotube Vacuum Electronics

http://www.freepatentsonline.com/7176478.pdf

Vacuum tubes predate transistors as the switching element of choice and still have several advantages such as higher switching speeds (since electrons have higher mobility in vacuum than silicon). Unfortunately power requirements and size make vacuum electronics impractical on a large scale, that is of course unless someone invents a high efficiency nanoscale electron emitting element. This patent proposes one way to create such vacuum nanoelectronics. Claim 1 reads:

1. A diode, comprised of two electrodes laterally shifted from each other and placed on non conductive substrate, wherein the first electrode includes a dielectric layer deposited on the substrate, a conductive layer placed on top of said dielectric layer and a nanotube placed on top of said first conductive layer, the axis of said nanotube being essentially normal to one of the edges of the said conductive layer while said nanotube protrudes beyond said one of the edges of said conductive layer into the area of a second electrode which includes a conductive layer placed on the substrate next to said one of the edges of said first conductive layer, so that said nanotube is located above and protrudes into the area of said second electrode.