US Patent 7288773 - InAs nanowire field emitter

http://www.freepatentsonline.com/7288773.html

This patent, based on a collaboration between FEI company and Philips electronics, teaches a semiconductor field emitter formed from InAs nanowires. Claim 1 reads:

1. An electron source suitable for use in a charged-particle apparatus, in which source a beam of electrons can be extracted from an electrode that is subjected to at least one of an electric potential, thermal excitation and photonic excitation, characterized in that at least part of the electrode comprises semiconductor material having a conduction band that is quantized into discrete energy levels.

The breadth of this patent claim is somewhat surprising since semiconducting single walled carbon nanotubes, which have quantized conductance bands, have been proposed for field emission over a decade ago (see http://onversity.com/doc/nanotube1.pdf or US Patent 5,773,921). Unfortunately this patent was allowed without any consideration of such prior art.