A novel photocathode employing a conduction band barrier is described. Incorporation of a barrier optimizes a trade-off between photoelectron transport efficiency and photoelectron escape probability. The barrier energy is designed to achieve a net increase in photocathode sensitivity over a specific operational temperature range.

Systems and methods for obtaining fast, spin-polarized electrons from an edge or tip or cusp of a target material, e.g., a sharp GaAs crystal edge or tip, or a cusp, which naturally incorporates optical reversibility. A source of fast spin-polarized electrons may include a target material including a sharp tip or tip portion or a sharp edge or a cusp, the tip or tip portion including at least two intersecting edges, and a pulsed light source configured to emit one or more light pulses focused on the sharp tip or tip portion or the sharp edge or the cusp to thereby induce emission of spin-polarized electrons from the sharp tip or tip portion or the sharp edge or the cusp of the target material.

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.

An electron source system utilizing photon enhanced thermionic emission to create a source of well controlled electrons for injection into a series of lenses so that the beam can be fashioned to meet the particular specification for a given use is disclosed. Because of the recent increased understanding and characterization of the bandgap in certain materials, a simplified system can now be realized to overcome the potential barrier at the surface. With this system, only low electric fields with moderate temperatures (500 C.) are required. The resulting system enables much easier focusing of the electron beam because the random component of the energy of the electrons is much lower than that of a conventional system. The system comprises an emitter of wide bandgap material, a first light source and a heating element wherein the heating element provides moderate warming to the wide bandgap material and the light source provides photonic excitation to the material, causing electrons to be emitted into an optical system to manipulate the emitted electrons.

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 structure, which can include one or more of Cs.sub.2Te, CsKTe, CsI, CsBr, GaAs, GaN, InSb, CsKSb, or a metal, has a protective film on an exterior surface. The protective film includes one or more of ruthenium, nickel, platinum, chromium, copper, gold, silver, aluminum, or an alloy thereof. The protective film can have a thickness from 1 nm to 10 nm. The photocathode structure can be used in an electron beam tool like a scanning electron microscope.

The present invention improves sensitivity of the ultraviolet band of a photoelectric surface. A photoelectric surface includes a window material that transmits ultraviolet rays, a conductive film that is formed on the window material and has conductivity, an intermediate film 4 that is formed on the conductive film and is formed of MgF.sub.2, and a photoelectric conversion film that is formed on the intermediate film 4 and is formed of CsTe. Since the photoelectric surface includes the intermediate film 4 formed of MgF.sub.2, the sensitivity of the ultraviolet band is improved.

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.

Embodiments of the present invention describe electrical potential energy to electrical kinetic energy converters, ozone generators, and light emitters. A system for energy conversion from electrical potential energy to electrical kinetic energy may include a discharge device and a power supply. The power supply can be coupled with the discharge device, and supplies energy to the discharge device to form an initial electric field. The discharge device may further include at least two electrodes that are either mesh electrodes or wire-array electrodes. Furthermore, a space between the at least two electrodes is filled with a gas medium and an electric field is created by the power supply in a normal direction relative to planes formed by the elements of electrodes.

An electron source system utilizing photon enhanced thermionic emission to create a source of well controlled electrons for injection into a series of lenses so that the beam can be fashioned to meet the particular specification for a given use is disclosed. Because of the recent increased understanding and characterization of the bandgap in certain materials, a simplified system can now be realized to overcome the potential barrier at the surface. With this system, only low electric fields with moderate temperatures (500 C.) are required. The resulting system enables much easier focusing of the electron beam because the random component of the energy of the electrons is much lower than that of a conventional system. The system comprises an emitter of wide bandgap material, a first light source and a heating element wherein the heating element provides moderate warming to the wide bandgap material and the light source provides photonic excitation to the material, causing electrons to be emitted into an optical system to manipulate the emitted electrons.