Material structures, systems and devices are disclosed. The material structures are active materials, which are able to emit UV/visible light under excitation by bias, by light beam or by electron beam. The input unit is a source of voltage/current or a source of light or a source of electron beam. The active unit is a material structure containing one or more layers of the described materials. The system may include a passive unit such as a ring resonator, a waveguide, coupler, grating or else. Additional units such as a control unit, readout unit or else may be also incorporated.

The distinguished characteristic of the present invention is that the UV or visible emission from the described structures cannot happen without the presence of at least one of the following quasi-particles: surface plasmons, surface plasmon polaritons, bulk plasmons and/or bulk plasmon polaritons. These quasi-particles assist the UV and the visible light emission.

Material structures, systems and devices are disclosed. The material structures are active materials, which are able to emit UV/visible light under excitation by bias, by light beam or by electron beam. The input unit is a source of voltage/current or a source of light or a source of electron beam. The active unit is a material structure containing one or more layers of the described materials. The system may include a passive unit such as a ring resonator, a waveguide, coupler, grating or else. Additional units such as a control unit, readout unit or else may be also incorporated.

The distinguished characteristic of the present invention is that the UV or visible emission from the described structures cannot happen without the presence of at least one of the following quasi-particles: surface plasmons, surface plasmon polaritons, bulk plasmons and/or bulk plasmon polaritons. These quasi-particles assist the UV and the visible light emission.

An optical heating method includes a process (a) in which an object to be treated containing a wide band gap semiconductor is irradiated with ultraviolet light having a peak wavelength in a range of 175 nm to 370 nm emitted from a UV-LED light source through a window member to heat the object to be treated.

A light-emitting device includes a substrate comprising a base member, a first wiring, a second wiring, and a via hole; at least one light-emitting element electrically connected to and disposed on the first wiring; and a covering member having light reflectivity and covering a lateral surface of the light-emitting element and a front surface of the substrate. The base member defines a plurality of depressed portions separated from the via hole in a front view and opening on a back surface and a bottom surface of the base member. The substrate includes a third wiring covering at least one of inner walls of the plurality of depressed portions and electrically connected to the second wiring. A depth of each of the plurality of depressed portions defined from the back surface toward the front surface is larger on a bottom surface side than on an upper surface side of the base member.

A light-emitting device includes a substrate comprising a base member, a first wiring, a second wiring, and a via hole; at least one light-emitting element electrically connected to and disposed on the first wiring; and a covering member having light reflectivity and covering a lateral surface of the light-emitting element and a front surface of the substrate. The base member defines a plurality of depressed portions separated from the via hole in a front view and opening on a back surface and a bottom surface of the base member. The substrate includes a third wiring covering at least one of inner walls of the plurality of depressed portions and electrically connected to the second wiring. A depth of each of the plurality of depressed portions defined from the back surface toward the front surface is larger on a bottom surface side than on an upper surface side of the base member.

Described herein are solid-state devices based on graphene in a Field Effect Transistor (FET) structure that emits high frequency Electromagnetic (EM) radiation using one or more DC electric fields and periodic magnetic arrays or periodic nanostructures. A number of devices are described that are capable of generating and emitting electromagnetic radiation.

Described herein are solid-state devices based on graphene in a Field Effect Transistor (FET) structure that emits high frequency Electromagnetic (EM) radiation using one or more DC electric fields and periodic magnetic arrays or periodic nanostructures. A number of devices are described that are capable of generating and emitting electromagnetic radiation.

An epitaxial wafer comprises an epitaxial layer disposed on a substrate. The epitaxial layer comprises first to third semiconductor layers. The third semiconductor layer has a thickness that is thicker than that of the first semiconductor layer. A second doping density of the second semiconductor layer is between a first doping density of the first semiconductor layer and a third doping density of the third semiconductor layer.

An epitaxial wafer comprises an epitaxial layer disposed on a substrate. The epitaxial layer comprises first to third semiconductor layers. The third semiconductor layer has a thickness that is thicker than that of the first semiconductor layer. A second doping density of the second semiconductor layer is between a first doping density of the first semiconductor layer and a third doping density of the third semiconductor layer.

A silicon-based quantum dot device (1) is disclosed. The device comprises a substrate (8) and a layer (7) of silicon or silicon-germanium supported on the substrate which is configured to provide at least one quantum dot (5.sub.1, 5.sub.2: FIG. 5). The layer of silicon or silicon-germanium has a thickness of no more than ten monolayers. The layer of silicon or silicon-germanium may have a thickness of no more than eight or five monolayers.