Abstract: A terahertz interaction circuit includes a waveguide through which electromagnetic waves pass, the waveguide having a folded shape and including a narrow open cavity portion; and an electron beam tunnel through which an electron beam passes, the electron beam tunnel penetrating through the waveguide.

Abstract: An electron beam focusing electrode and an electron gun using the same may include a plate having a polygonal through-hole; at least a projecting portion formed on at least one side of the through-hole. By using the electron beam focusing electrode, a spreading phenomenon of an electron beam having a rectangular cross section may be reduced. Further, the output of the electron gun may be increased, and electron beams may be easily focused.

Abstract: A method of multi-stage substrate etching is provided.

Abstract: Example embodiments provide a method of fabricating a triode-structure field-emission device. A cathode, an insulating layer, and a gate metal layer may be sequentially formed on a substrate. A first resist pattern having a first opening and a second resist pattern having a second opening smaller than the first opening may be formed to be sequentially laminated on the gate metal layer. Then, the gate metal layer and the insulating layer may be etched using the first resist pattern to form a gate electrode and an insulating layer having a first hole and a second hole corresponding to the first opening. A catalyst layer may be formed on the cathode exposed through the first and second holes using the second resist pattern. After the first resist pattern, second resist pattern, and the catalyst layer on the second resist pattern are removed, an emitter may be formed on the catalyst layer in the second hole.

Abstract: A terahertz oscillator may include a first insulating layer, an electron emitter on the first insulating layer, adapted to emit an electron beam, and including a cathode, an anode, an oscillating circuit, and a collector sequentially disposed, spaced apart from each other, on the first insulating layer in a direction in which the electron beam is emitted from the electron emitter, wherein the oscillating circuit converts energy of the electron beam to energy of an electromagnetic wave, and wherein the collector collects the electron beam, an output unit adapted to emit the electromagnetic wave from the oscillating circuit to outside of the terahertz oscillator, and an electron emitting material layer. The cathode may include a first curved portion that extends in a direction perpendicular to the first insulating layer. The electron emitting material layer may be on an inner surface of the first curved portion of the cathode.

Abstract: A method of multi-stage substrate etching and a terahertz oscillator manufactured by using the method are provided. The method comprises the steps of forming a first mask pattern on any one surface of a first substrate, forming a hole by etching the first substrate using the first mask pattern as an etching mask, bonding, to the first substrate, a second substrate having the same thickness as a depth to be etched, forming a second mask pattern on the second substrate bonded, forming a hole by etching the second substrate using the second mask pattern as an etching mask, and removing an oxide layer having the etching selectivity between the first substrate and the second substrate.

Abstract: Provided is a microelectromechanical system (MEMS) that includes a first structure and second structure. The first structure and second structure may each include a first substrate and a second substrate. The first substrate of each structure may have first and second surfaces that face each other. The first substrate may include a via etching hole pattern penetrating the first surface and the second surface and a first non-via etching hole pattern penetrating the first surface. The second substrate of each structure may have third and fourth surfaces that face each other. The second substrate may include a second non-via etching hole pattern penetrating the third surface in a position corresponding to the via etching hole pattern of the first substrate. In the microelectromechanical system (MEMS) the second surface of the first substrate and the third surface of the second substrate may be bonded together.

Abstract: Provided are 3-dimensional standing type metamaterial structures and methods of fabricating the same. The 3-dimensional metamaterial structure includes a substrate; and a resonator, which includes a fixing unit fixed to the substrate; and a plurality of arms, which extend from the fixing unit and are curved upward on the substrate, wherein permittivity, permeability, and refractive index of the metamaterial structure in a predetermined frequency band differ from permittivity, permeability, and refractive index of the substrate. The resonator may be easily fabricated in MEMS/NEMS (micro-electro-mechanical system/nano-electro-mechanical system) processes.

Abstract: A terahertz interaction circuit is provided. The terahertz interaction circuit includes a waveguide and an electron beam tunnel. The waveguide has a folded shape and in which an electromagnetic wave propagates. The electron beam tunnel is formed to penetrate through the waveguide. An electron beam passes through the electron beam tunnel. The waveguide includes a ridge portion in which a portion of a surface of the waveguide protrudes into the waveguide.

Abstract: A metamaterial structure is provided, including a substrate and a plurality of resonators that are provided on different surfaces of the substrate or different layers of the substrate. The resonators have resonance characteristics different from each other, and the metamaterial structure has a permittivity, a permeability, and a refractive index respectively different from those of the substrate in a predetermined frequency bandwidth.

Abstract: A method of multi-stage substrate etching and a terahertz oscillator manufactured by using the method are provided. The method comprises the steps of forming a first mask pattern on any one surface of a first substrate, forming a hole by etching the first substrate using the first mask pattern as an etching mask, bonding, to the first substrate, a second substrate having the same thickness as a depth to be etched, forming a second mask pattern on the second substrate bonded, forming a hole by etching the second substrate using the second mask pattern as an etching mask, and removing an oxide layer having the etching selectivity between the first substrate and the second substrate, whereby the etched bottom is made uniformly even in a deep step, the edge curvature is minimized, and a T-shape is prevented from being formed on the etched wall face to thereby improve the etching quality.

Abstract: A nano-resonator including a beam having a composite structure may include a silicon carbide beam and/or a metal conductor. The metal conductor may be vapor-deposited on the silicon carbide beam. The metal conductor may have a density lower than a density of the silicon carbide beam.

Abstract: A terahertz radiation source includes: a cathode configured to emit an electron beam, an anode configured to focus the electron beam emitted from the cathode; a collector facing the cathode and configured to collect the emitted electron beam focused by the anode; an oscillating circuit positioned between the anode and the collector and configured to convert energy of a passing electron beam into electromagnetic wave energy; and an output unit connected to the oscillating circuit and configured to externally emit the electromagnetic wave energy.

Abstract: A method for driving a field emission device (FED) applies an alternating (AC) voltage as a driving voltage for emitting electrons in a field emission device comprising cathode electrode including an emitter and an anode electrode facing the cathode electrode. A method for aging an FED uses a constant voltage so that electrons cannot be emitted from the electron emission source, and an AC voltage so that electrons can be periodically emitted from the emitter when the FED is aged.

Abstract: Provided is a microelectromechanical system (MEMS) that includes a first structure and second structure. The first structure and second structure may each include a first substrate and a second substrate. The first substrate of each structure may have first and second surfaces that face each other. The first substrate may include a via etching hole pattern penetrating the first surface and the second surface and a first non-via etching hole pattern penetrating the first surface. The second substrate of each structure may have third and fourth surfaces that face each other. The second substrate may include a second non-via etching hole pattern penetrating the third surface in a position corresponding to the via etching hole pattern of the first substrate. In the microelectromechanical system (MEMS) the second surface of the first substrate and the third surface of the second substrate may be bonded together.

Abstract: An electromagnetic wave transmission filter may include a substrate and one or more coils. The one or more coils may be at least partly disposed in an opening through the substrate. An electromagnetic camera may include an electromagnetic wave detector array, including a plurality of detector cells for detecting electromagnetic waves, and an electromagnetic wave transmission filter disposed in front of the electromagnetic wave detector array to provide each of the detector cells with an electromagnetic wave of a certain wavelength. The electromagnetic wave transmission filter may includes a substrate and a plurality of coils. At least one of the plurality of coils may be at least partly disposed in each of a plurality of openings through the substrate.

Abstract: A solar cell includes a plurality of nanowires arranged such that diameters of the nanowires sequentially increase in a first direction along a path of incident light. In a method of forming nanowires, a catalyst layer is formed on a substrate, a plurality of nanoparticles are formed by thermally processing the catalyst layer, and nanowires are grown from the plurality of nanoparticles. The catalyst layer has a thickness that increases in a first direction, and the plurality of nanoparticles have diameters that increase in the first direction.

Abstract: A method of fabricating a field emission array type light emitting unit that includes a rear substrate including a plurality of cathodes and a plurality of carbon nanotube emitters on a front side, a front substrate including a plurality of anodes and a phosphor layer on a rear side, wherein the rear substrate and the front substrate are arranged at a distance apart from each other and a plurality of spacers are arranged between the rear substrate and the front substrate, the plurality of spacers being adapted to maintain constant the distance, the method includes producing a diffusion pattern by wet etching a front side of the front substrate.

Abstract: Provided are an electron multiplier electrode using a secondary electron extraction electrode and a terahertz radiation source using the electron multiplier electrode. The electron multiplier electrode includes: a cathode; an emitter disposed on the cathode and extracting electron beams; a gate electrode for switching the electron beams, the gate electrode being disposed on the cathode to surround the emitter; and a secondary electron extraction electrode disposed on the gate electrode and including a secondary electron extraction layer extracting secondary electrons due to collision of the electron beams.

Abstract: An electronic mirror and a method for displaying an image using the electronic mirror are provided. The electronic mirror may include a display unit, a detecting unit and a control unit. The detecting unit may receive a signal transmitted from the outside. The control unit may control the detecting unit and the display unit to display the signal received at the detecting unit on the display unit as an image. The image displayed on the display unit may be output from the electronic mirror through the detecting unit. The electronic mirror may further include a reflecting unit. A light from the outside may pass through the detecting unit and the display unit and then be reflected on the reflecting unit. The reflected light may be output from the electronic mirror through the display unit and the detecting unit.