Improved ultraviolet field-emission lamps can be safely deployed close to people because they eliminate the use of toxic materials, mitigate heating issues, and emit light in a wavelength range that is safe for human exposure.

A photocathode structure, which can include an alkali halide, has a protective film on an exterior surface of the photocathode structure. The protective film includes ruthenium. This protective film can be, for example, ruthenium or an alloy of ruthenium and platinum. The protective film can have a thickness from 1 nm to 20 nm. The photocathode structure can be used in an electron beam tool like a scanning electron microscope.

A photocathode structure, which can include an alkali halide, has a protective film on an exterior surface of the photocathode structure. The protective film includes ruthenium. This protective film can be, for example, ruthenium or an alloy of ruthenium and platinum. The protective film can have a thickness from 1 nm to 20 nm. The photocathode structure can be used in an electron beam tool like a scanning electron microscope.

Electron source designs are disclosed. The emitter structure, which may be silicon, has a layer on it. The layer may be graphene or a photoemissive material, such as an alkali halide. An additional layer between the emitter structure and the layer or a protective layer on the layer can be included. Methods of operation and methods of manufacturing also are disclosed.

A photocathode can include a body fabricated of a wide bandgap semiconductor material, a metal layer, and an alkali halide photocathode emitter. The body may have a thickness of less than 100 nm and the alkali halide photocathode may have a thickness less than 10 nm. The photocathode can be illuminated with a dual wavelength scheme.

A flat top laser beam is used to generate an electron beam with a photocathode that can include an alkali halide. The flat top profile can be generated using an optical array. The laser beam can be split into multiple laser beams or beamlets, each of which can have the flat top profile. A phosphor screen can be imaged to determine space charge effects or electron energy of the electron beam.

An electron emitter structure includes an electron emission layer which is arranged to have a first side and a second side, and an electron accelerating structure which is arranged on the first side of the electron emission layer. The electron emission layer has a mixture of metals so as to be atmospherically stable. The electron accelerating structure has at least one electrode which is electrically insulated from the electron accelerating structure so as to form an acceleration path which allows electrons which are released from the electron emission layer to be selectively accelerated upon generation of an adjustable electric field. The acceleration path has a length l of from 10 nm to 1 ?m.

A package having a field emission element may include a handle layer; a buried layer stacked on the handle layer; a device layer stacked on the buried layer; an insulating layer stacked in an upper region of the device layer; a gate electrode stacked in an upper region of the insulating layer; and at least one light-emitting element disposed in a lower region of the device layer, and configured to emit light through the device layer. The insulating layer may be configured with a plurality of insulating regions separated by first separation regions, and the gate electrode may be configured with a plurality of metal regions separated by second separation regions. The device layer may be provided with protruding portions disposed to protrude between the first separation regions between the insulating regions and the second separation regions between the metal regions.

The present disclosure relates to a field emission device that generates X-rays by emitting an electron beam, and an X-ray generating apparatus using the same, including a semiconductor substrate; a bottom electrode disposed below the semiconductor substrate; an insulating layer disposed above the semiconductor substrate; a gate electrode disposed on the insulating layer; and, a top electrode disposed on the gate electrode; wherein the gate electrode is composed of a material satisfying at least one of a first condition for work function, a second condition for Gibbs free energy of a redox reaction with the insulating layer, a third condition for sublimation energy, and a fourth condition for electron mean free path.