A method for growing on a substrate strongly aligned uniform cross-section semiconductor composite nanocolumns is disclosed. The method includes: (a) forming faceted pyramidal pits on the substrate surface; (b) initiating nucleation on the facets of the pits; and; (c) promoting the growth of nuclei toward the center of the pits where they coalesce with twinning and grow afterwards together as composite nanocolumns. Multi-quantum-well, core-shell nanocolumn heterostructures can be grown on the sidewalls of the nanocolumns. Furthermore, a continuous semiconductor epitaxial layer can be formed through the overgrowth of the nanocolumns to facilitate fabrication of high-quality planar device structures or for light emitting structures.

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.

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.

An electron emission device having a narrow electron energy range and excellent electron emitting efficiency, and an electron microscope using the electron emission device. An electron emission device having a laminated structure in which a first electrode, an electron accelerating layer made of an insulating film, and a second electrode are laminated in this order, in which the second electrode through which electrons transmit and from whose surface electrons emit, and the energy width of the emitted electrons is 100 meV or more and 600 meV or less. For example, graphene having one or more layers and 20 layers or less can be used as the second electrode, and hexagonal boron nitride can be used as the insulating film.

An electron emission device having a narrow electron energy range and excellent electron emitting efficiency, and an electron microscope using the electron emission device. An electron emission device having a laminated structure in which a first electrode, an electron accelerating layer made of an insulating film, and a second electrode are laminated in this order, in which the second electrode through which electrons transmit and from whose surface electrons emit, and the energy width of the emitted electrons is 100 meV or more and 600 meV or less. For example, graphene having one or more layers and 20 layers or less can be used as the second electrode, and hexagonal boron nitride can be used as the insulating film.

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.

An electrical device comprising a substrate of diamond material and elongate metal protrusions extending into respective recesses in the substrate. Doped semiconductor layers, arranged between respective protrusions and the substrate, behave as n type semiconducting material on application of an electric field, between the protrusions and the substrate, suitable to cause a regions of positive space charge within the semiconductor layers.

An electrical device comprising a substrate of diamond material and elongate metal protrusions extending into respective recesses in the substrate. Doped semiconductor layers, arranged between respective protrusions and the substrate, behave as n type semiconducting material on application of an electric field, between the protrusions and the substrate, suitable to cause a regions of positive space charge within the semiconductor layers.

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 utilizes an field emitter array (FEA) integrally formed on a silicon substrate to enhance photoelectron emissions, and a thin boron layer disposed directly on the output surface of the FEA to prevent oxidation. The field emitters are formed by protrusions having various shapes (e.g., pyramids or rounded whiskers) disposed in a two-dimensional periodic pattern, and may be configured to operate in a reverse bias mode. An optional gate layer is provided to control emission currents. An optional second boron layer is formed on the illuminated (top) surface, and an optional anti-reflective material layer is formed on the second boron layer. An optional external potential is generated between the opposing illuminated and output surfaces. An optional combination of n-type silicon field emitter and p-i-n photodiode film is formed by a special doping scheme and by applying an external potential. The photocathode forms part of sensor and inspection systems.