104 results about "Fermi energy" patented technology

The influence of surface geometry on metal properties is studied within the limit of the quantum theory of free electrons. It is shown that a metal surface can be modified with patterned indents to increase the Fermi energy level inside the metal, leading to decrease in electron work function. This effect would exist in any quantum system comprising fermions inside a potential energy box. Also disclosed is a method for making nanostructured surfaces having perpendicular features with sharp edges.

The present invention is directed to a semiconductor device that includes at least one p-n junction including a p-type material, an n-type material, and a depletion region. The at least one p-n junction is configured to generate bulk photocurrent in response to incident light. The at least one p-n junction is characterized by a conduction band energy level, a valence band energy level and a surface Fermi energy level. The surface Fermi energy level is pinned either near or above the conduction band energy level or near or below the valence band energy level. A unipolar barrier structure is disposed in a predetermined region within the at least one p-n junction. The unipolar barrier is configured to raise the conduction band energy level if the surface Fermi energy level is pinned near or above the conduction band energy level or lower the valence band energy level if the surface Fermi energy level is pinned near or below the valence band energy level such that the unipolar barrier is configured to propagate the bulk photocurrent and substantially block surface leakage current. The at least one p-n junction and the unipolar barrier are integrally formed.

A magnetic body composed of non-magnetic material, includes a plurality of localized electron regions in each of which at least one electron is confined to form a localized spin, a barrier potential region having a higher energy than a Fermi energy of an electron in the localized electron region and permitting an electron to be confined in the respective localized electron regions, and a conductive electron region including a conductive electron system having a lower energy than an energy of the barrier potential region, wherein the respective localized electron regions are disposed separate from one another via the barrier potential region and the conductive electron region.

An apparatus and method for making it. Some embodiments include a light-emitting device having a light-emitting active region; a tunneling-barrier (TB) structure facing adjacent the active region; a TB grown-epitaxial-metal-mirror (TB-GEMM) structure facing adjacent the TB structure, wherein the TB-GEMM structure includes at least one metal is substantially lattice matched to the active region; and a conductivity-type III-nitride crystal structure adjacent facing the active region opposite the TB structure. In some embodiments, the active region includes an MQW structure. In some embodiments, the TB-GEMM includes an alloy composition such that metal current injectors have a Fermi energy potential substantially equal to the sub-band minimum energy potential of the MQW. Some embodiments further include a second mirror (optionally a GEMM) to form an optical cavity between the second mirror and the TB-GEMM structure. In some embodiments, at least one of the GEMM is deposited on, and lattice matched to, a substrate.

The invention discloses an asymmetrical electrode two-dimensional material/graphene heterojunction cascaded photodetector and a manufacturing method thereof. The detector comprises a Si/SiO2 substrate, a first electrode is arranged on the Si/SiO2 substrate, a two-dimensional material layer is arranged on the first electrode, a second electrode is arranged on the two-dimensional material layer, and the two-dimensional material layer is an n-layer heterojunction formed by graphene and two-dimensional material which are overlapped. The asymmetrical electrodes with different work functions are adopted, formation of a Fermi energy level difference from the first electrode to the second electrode is promoted, photocarriers are generated and then quickly diffused to an external circuit, quick combination of an electron hole can be avoided due to existence of the energy level difference, and the photo response of the device can be enhanced; and as the graphene and the two-dimensional material are combined, the high carrier mobility and the super quick response time of the graphene, and the high absorption rate towards light by the two-dimensional material are used respectively, and a super quick and super high-response photodetector can be realized.

An n-type TFT and a p-type TFT are realized by selectively changing only a cover coat without changing a TFT material using an equation for applying the magnitude of a difference in the Fermi energy between an interface of semiconductor and an electrode and between an interface of semiconductor and insulator. At this time, in order to configure a predetermined circuit, the process is performed, as a source electrode and a drain electrode of the p-type TFT and a source electrode and a drain electrode of the n-type TFT being connected all, respectively, and an unnecessary interconnection is cut by irradiating light using a scanning laser exposure apparatus or the like.

Pixels in a focal plane array are defined by controlled variation of the Fermi energy at the surface of the detector array. Varying the chemical composition of the semiconductor at the detector surface produces a corresponding variation in the surface Fermi energy which produces a corresponding variation in the electric field and electrostatic potential in the bulk semiconductor below the surface. This defines pixels by having one Fermi energy at the surface of each pixel and a different Fermi energy at the surface between pixels. Fermi energy modulation can also be controlled by applying an electrostatic potential voltage V1 to the metal pad defining each pixel, and applying a different electrostatic potential voltage V2 to an interconnected metal grid covering the gaps between all the pixel metal pads. Methods obviate the need to etch deep trenches between pixels, resulting in a more manufacturable quasi-planar process without sacrificing performance.

The invention relates to a reflection type circular polarization plane metalens on the basis of graphene metasurfaces, and belongs to the field of novel artificial electromagnetic materials and optical devices. The reflection type circular polarization plane metalens comprises a lower metal substrate layer, a middle dielectric layer and controllable bias voltage devices. A graphene metasurface layer with rectangular pore arrays is arranged on the upper metal substrate layer and is used for controlling polarization directions and propagation characteristics of reflected waves, and the controllable bias voltage devices are connected with the graphene metasurfaces and metal substrates, so that Fermi energy of the graphene metasurface layer can be adjusted, the electric conductivity of graphene layers can be changed, and the focal length of the reflection type circular polarization plane metalens which is a graphene metalens can be dynamically tuned. Compared with transmission type metal metasurface lenses with excessively low transmission efficiency, the reflection type circular polarization plane metalens has the advantages that the reflection type circular polarization plane metalens is suitable to be applied to actual scenes; focusing locations are flexible and controllable, and accordingly the reflection type circular polarization plane metalens is high in practicality; the requirements of certain distribution laws can be met by rotation angles of rectangular pores in the reflection type circular polarization plane metalens and the lengths of the rectangular pores, and fixed-frequency electromagnetic wave focal lengths can be regulated and controlled.

Herein, provided are heavily doped colloidal semiconductor nanocrystals and a process for introducing an impurity to semiconductor nanoparticles, providing control of band gap, Fermi energy and presence of charge carriers. The method is demonstrated using InAs colloidal nanocrystals, which are initially undoped, and are metal-doped (Cu, Ag, Au) by adding a metal salt solution.

The invention provides a low Schottky barrier semiconductor structure. The semiconductor structure comprises a substrate, a gate stack, one or more layers of side walls, metal source and drain electrodes and an insulating layer film, wherein the gate stack is formed on the substrate, the one or more layers of side walls are located at two sides of the gate stack, the metal source and drain electrodes are formed at two sides of the gate stack and located in the substrate, and the insulating layer film is located between the substrate and the metal source and drain electrodes. Through the embodiment of the invention, the insulating layer film formed between the substrate and the metal source and drain electrodes can prevent the band gap state caused by the metal source and drain electrodes from entering a channel, thereby the Fermi energy level pinning phenomenon is relieved, the Schottky barrier height is reduced, and the switching current ratio of a transistor is increased.

Disclosed is an organic light emitting device comprising a first electrode, two or more organic compound layers, and a second electrode, wherein the first electrode comprises a conductive layer and an n-type organic compound layer which is in contact with the conductive layer, one of the organic compound layers interposed between the n-type organic compound layer of the first electrode and the second electrode is a p-type organic compound layer forming an NP junction together with the n-type organic compound layer of the first electrode, energy levels of the layers satisfy the following Expressions (1) and (2), and one or more layers interposed between the p-type organic compound layer and the second electrode are n-doped with alkali earth metal:

0 eV<E_nL−E_F1≦4 eV  (1)

E_pH−E_nL≦1 eV  (2)

• • where E_F1 is a Fermi energy level of the conductive layer of the first electrode, E_nL is an LUMO (lowest unoccupied molecular orbital) energy level of the n-type organic compound layer of the first electrode, and E_pH is an HOMO (highest occupied molecular orbital) energy level of the p-type organic compound layer forming the NP junction together with the n-type organic compound layer of the first electrode.

The invention discloses a terahertz converter capable of realizing power-absorbing mode and polarization conversion mode switching. The terahertz converter is composed of two graphene layers, one metal polarization conversion metasurface layer, one metal reflecting layer and three medium layers; each graphene layer is composed of an electrode layer and a graphene meta-surface layer adhered on an upper surface of the electrode layer; bias voltage V1 is applied between the graphene metasurface layer of one graphene layer and the electrode layer so as to adjust the Fermi energy EF1 of the graphene layer; and meanwhile, the bias voltage V1 is applied between the graphene metasurface layer of the other graphene layer and the electrode layer so as to adjust the Fermi energy EF2 of the graphene layer; when one of the Fermi energy EF1 and/or Fermi energy EF2 exceeds a switching threshold, the terahertz converter works at a power-absorbing mode; or the terahertz converter works at a polarization conversion mode. The terahertz converter provided by the invention can solve the problem that the single device cannot realize the polarization conversion and the power absorption at the same time.

The invention provides a FinFET manufacturing method. Before or after a step of forming a high-k gate dielectric layer surrounding the two sides and the upper side of a fin, the fin is annealed in a mixed atmosphere of heavy hydrogen and inert gas, dangling bonds of silicon in the fin are eliminated, induced band gap state or oxygen vacancy at a fin interface are reduced, the problem of Fermi energy level pinning in the high-k dielectric layer is improved, and the fin interface is smoothed, thereby reducing the number of defects in the high-k dielectric layer, suppressing the charge trap effect, improving the threshold voltage drift and improving the performance of FinFET devices.

Disclosed is an organic light emitting device and a method for manufacturing the same. The organic light emitting device includes a first electrode, one or more organic compound layers, and a second electrode. The first electrode includes a conductive layer and an n-type organic compound layer disposed on the conductive layer. A difference in energy between an LUMO energy level of the n-type organic compound layer of the first electrode and a Fermi energy level of the conductive layer of the first electrode is 4 eV or less. One of the organic compound layers interposed between the n-type organic compound layer of the first electrode and the second electrode is a p-type organic compound layer forming an NP junction along with the n-type organic compound layer of the first electrode. A difference in energy between the LUMO energy level of the n-type organic compound layer of the first electrode and an HOMO energy level of the p-type organic compound layer is 1 eV or less. One or more layers interposed between the conductive layer of the first electrode and the second electrode is n-doped or p-doped with an organic material or an inorganic material.

The invention provides a tunable terahertz graphene metamaterial absorber. The tunable terahertz graphene metamaterial absorber comprises a four-layer structure laminated together: including a patterned graphene metamaterial top layer, a dielectric middle layer, a metal bottom layer and a substrate; the metal bottom layer is arranged on the substrate; the dielectric middle layer is arranged on themetal bottom layer; and the patterned graphene metamaterial top layer is arranged on the dielectric middle layer. Graphene is adopted to replace the conventional metal structure to establish the terahertz metamaterial absorber, and the Fermi energy of two graphene circular plates are tuned through static doping, so that the resonance characteristic of the two graphene circular plates and the nearfield coupling characteristic between the circular plates can be controlled, thereby realizing flexible control on the absorption strength, bandwidth and frequency of the absorber.

The invention discloses a two-dimensional metamaterial functional device based on grapheme, which comprises a reflected layer on the substrate in sequence order, a dielectric layer and a grapheme micro-nano structure layer, wherein, the grapheme micro-nano structure layer comprises a plurality of configurated grapheme assembly units, each the grapheme assembly unit comprises a plurality of grapheme scattering units, the structure of a a plurality of grapheme scattering units are same from each other. The technical scheme realizes different functional device. In the functional devices, by using a single electrode the Fermi energy levels of the graphene scattering unit is modulated uniformly, the resonant frequency of the graphene scattering unit is controlled, combining with the high mobility characteristics of graphene, the dynamic regulation of incoming light transmission is achieved. In addition, high conversion efficiency can be obtained because of the strong reflectivity light of PB phase shift in the graphene two-dimensional supermaterials.

The invention discloses a method for measuring the carrier concentration of graphene by virtue of Goos-Hanchen shift. The variation of the Goos-Hanchen shift after introduction of the graphene is measured to measure the photoconductivity of the graphene and further measure the carrier concentration of the graphene. The method specifically comprises the following steps: covering a metamaterial with a refractive index approaching to zero with a single layer of graphene, obliquely emitting a terahertz beam to the surface of the graphene, detecting the Goos-Hanchen shift of reflected light, and calibrating the carrier concentration or the Fermi energy level of the graphene according to a relationship between the calibrated Goos-Hanchen shift and the carrier concentration or the Fermi energy level of the graphene. According to the method, a method of optically measuring the Goos-Hanchen shift without direct contact with a graphene sample is adopted, and is a non-contact and damage-free measurement method, so that additional influencing factors are avoided.

A method for enhancing the operating characteristics of memory devices (400C), such as flash memory devices, by manipulating the Fermi energy levels of the substrate (406) and the floating gate (404). In so doing, the gap between the minimum conduction band energy level (408) and the Fermi energy level (412) of the floating gate (404) is extended so as to readily facilitate the movement of electrons from the substrate (406) into the floating gate (404).

A quantum well structure is provided that includes two or more quantum well layers coupled by at least one barrier layer such that at least one of a piezo-electric field and a pyro-electric field is produced. The quantum well structure is sufficiently doped to cause a Fermi energy to be located between ground states and excited states of the coupled quantum well layers. The quantum well structure can be incorporated into a layered semiconductor to form optical devices such as a laser or optical amplifier.

The invention provides a measuring method for intermediate-state energy level of an energy gap of a semiconductor material. The measuring method comprises the following steps: step I: acquiring dynamic data, under different excitation wavelengths, of the semiconductor material, and distinguishing dynamics of conduction band electrons from dynamics of bound state electrons; step II: mapping according to value, at the same time, of the dynamic data after pulse excitation, thereby obtaining a forbidden band excitation scanning spectrum of the semiconductor material; step III: determining fermi energy level of the semiconductor material; step IV: according to the fermi energy level and the forbidden band excitation scanning spectrum, representing a bound state of the semiconductor material; step V: drawing a band gap intermediate-state energy level diagram of the semiconductor material. According to the measuring method, the position of fermi energy level can be determined and the intermediate-state energy level of the semiconductor material can be symmetrically represented, so that the design of photocatalysts is guided to develop towards practicability and high efficiency.