A field emission device comprises one or more emitter elements, each having a high aspect ratio structure with a nanometer scaled cross section; and one or more segmented electrodes, each surrounding one of the one or more emitters. Each of the one or more segmented electrodes has multiple electrode plates. This abstract is provided to comply with rules requiring an abstract that will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.

A tunable photocathode for use in vacuum electronic devices includes a nanostructured photoemission layer including quantum confined nanostructures, such as quantum dots. The quantum confined nanostructures can be tuned (e.g., prepared to have various characteristics or parameters) in order to independently optimize various characteristics of the electron beam emitted by the photocathode. For example, by changing the material composition, size and geometry of the quantum confined nanostructures, the energy levels of the quantum confined nanostructures in the photoemission layer can be tuned to provide a photocathode having a high quantum efficiency, low emittance, fast response time to incident light pulses, long operational lifetime, and increased environmental stability compared with conventional photocathodes and cathodes in vacuum electronic devices.

A kind of photosensitive carbon nanotube slurry is disclosed. The photosensitive carbon nanotube slurry includes a first mixture and a second mixture. The first mixture includes carbon nanotubes, conducting particles, and a first organic carrier. The second mixture includes a photo polymerization monomer, a photo initiator, and a second organic carrier. The weight percentage of the first mixture and the second mixture ranges from about 50% to about 80% and about 20% to about 50%, respectively. Methods for making the photosensitive carbon nanotube slurry and methods for making cathode emitters using the photosensitive carbon nanotube slurry are also disclosed.

An intraoral radiation device, comprising a biocompatible intraoral receptacle with an X-ray source therein.

A cold cathode field emission electron source capable of emission at levels comparable to thermal sources is described. Emission in excess of 6 A/cm.sup.2 at 7.5 V/m is demonstrated in a macroscopic emitter array. The emitter has a monolithic and rigid porous semiconductor nanostructure with uniformly distributed emission sites, and is fabricated through a room temperature process which allows for control of emission properties. These electron sources can be used in a wide range of applications, including microwave electronics and x-ray imaging for medicine and security.

Methods of fabricating solar cell emitter regions using silicon nano-particles and the resulting solar cells are described. In an example, a method of fabricating an emitter region of a solar cell includes forming a region of doped silicon nano-particles above a dielectric layer disposed above a surface of a substrate of the solar cell. A layer of silicon is formed on the region of doped silicon nano-particles. At least a portion of the layer of silicon is mixed with at least a portion of the region of doped silicon nano-particles to form a doped polycrystalline silicon layer disposed on the dielectric layer.