56 results about "Non-radiative recombination" patented technology

A nitride semiconductor light-emitting element suppresses leakage currents and non-radiative recombination centers by providing, as an underlying layer of the active layer, a pit formation layer that reliably generates pits, while maintaining a good film quality, so that the internal quantum efficiency is improved, and the light-emitting characteristics are also improved. A nitride semiconductor lamination portion including at least an active layer for forming a light-emitting portion is present on a substrate, and a pit formation layer is formed as a superlattice layer of nitride semiconductor on the side of the substrate of the active layer. The pit formation layer generates pits in the end portions of threading dislocations that are generated in the nitride semiconductor layer on the side of the substrate.

Methods are disclosed for producing highly doped semiconductor materials. Using the invention, one can achieve doping densities that exceed traditional, established carrier saturation limits without deleterious side effects. Additionally, highly doped semiconductor materials are disclosed, as well as improved electronic and optoelectronic devices/components using said materials. The innovative materials and processes enabled by the invention yield significant performance improvements and/or cost reductions for a wide variety of semiconductor-based microelectronic and optoelectronic devices/systems. Materials are grown in an anion-rich environment, which, in the preferred embodiment, are produced by moderate substrate temperatures during growth in an oxygen-poor environment. The materials exhibit fewer non-radiative recombination centers at higher doping concentrations than prior art materials, and the highly doped state of matter can exhibit a minority carrier lifetime dominated by radiative recombination at higher doping levels and higher majority carrier concentrations than achieved in prior art materials. Important applications enabled by these novel materials include high performance electronic or optoelectronic devices, which can be smaller and faster, yet still capture or emit light efficiently, and high performance electronics, such as transistors, which can be smaller and faster, yet cooler.

In a field effect transistor such as high output FET or low noise HEMT, a layer for facilitating re-combination of carriers (for example a superlattice buffer layer), an undoped compound semiconductor layer having a higher resistance than a channel layer and the channel layer made of a compound semiconductor are layered successively. In the layer for facilitating re-combination of carriers, for example, oxygen of high concentration is introduced, to facilitate the non-radiative recombination which shortens the life of injected carriers. The layer for facilitating re-combination of carriers is also formed by forming the superlattice layer at a lower temperature than the channel layer. Thus, efficiency and voltageproofness on high frequency, high output power operation is improved further, and noises can be decreased further on high frequency, low noise operation.

Disclosed is a light emitting device employing nanowire phosphors. The light emitting device comprises a light emitting diode for emitting light having a first wavelength with a main peak in an ultraviolet, blue or green wavelength range; and nanowire phosphors for converting at least a portion of light having the first wavelength emitted from the light emitting diode into light with a second wavelength longer than the first wavelength. Accordingly, since the nanowire phosphors are employed, it is possible to reduce manufacturing costs of the light emitting device and to reduce light loss due to non-radiative recombination.

Photon absorption, and thus current generation, is hindered in conventional thin-film solar cell designs, including quantum well structures, by the limited path length of incident light passing vertically through the device. Optical scattering into lateral waveguide structures provides a physical mechanism to increase photocurrent generation through in-plane light trapping. However, the insertion of wells of high refractive index material with lower energy gap into the device structure often results in lower voltage operation, and hence lower photovoltaic power conversion efficiency. The voltage output of an InGaAs quantum well waveguide photovoltaic device can be increased by employing a III-V material structure with an extended wide band gap emitter heterojunction. Analysis of the light IV characteristics reveals that non-radiative recombination components of the underlying dark diode current have been reduced, exposing the limiting radiative recombination component and providing a pathway for realizing solar-electric conversion efficiency of 30% or more in single junction cells.

The invention discloses a method for preparing a patterned sapphire substrate for the extension of a gallium nitride-based LED, which comprises the following steps of: vapor-depositing a layer of thin film made from a low-refractive index material on the sapphire substrate by using conventional technology; preparing a mask pattern on the thin film with a photoresistor; transferring a pattern of a photosensitive resist mask onto the thin film by etching; and cleaning the substrate to remove the residual photoresistor. As threading dislocation is deflected from a vertical direction to a horizontal direction when GaN is extended and grown on the patterned substrate obtained by the method, the threading dislocation density of a GaN-based extension layer is reduced, the crystal quality of the extension layer is improved, a non-radiative recombination centre of a semiconductor luminous material is reduced, radiative recombination is enhanced and the light emitting efficiency of the LED can be improved; and the method has the advantages of easily controlled preparation process, simplicity, diversity, high rate of finished products and production cost reduction.

The invention discloses an epitaxial wafer for a flip infrared light-emitting diode, and belongs to the technical field of epitaxy of light emitting diodes. Layers are epitaxially formed on the same side of a substrate in sequence; an active layer comprises InGaAs quantum well layers and GaAsP barrier layers which alternate periodically; the period number is 2 to 6; the active layer adopts an InGaAs/GaAsP strain compensation quantum well structure; the strain compensation quantum well can restrain carriers to flow in place transversely to form non-radiative recombination by mistake, so that the quantum efficiency is improved.

The invention provides a perovskite composite LED with multiple quantum wells and a preparation method thereof. The perovskite composite LED with multiple quantum wells comprises a substrate, an electronic injection layer, a luminous layer, a hole injection layer and an electrode which are arranged in sequence; and the luminous layer comprises a CH3NDH3PbBr3 film and CH3NH3PbI3 quantum points embedded in the CH3NDH3PbBr3 film. The perovskite quantum points CH3NH3PbI3 with relatively narrow band gaps are embedded in the perovskite continuous phase CH3NDH3PbBr3 film with a relatively big band gap; and due to high electronics, hole mobility and carrier diffusion length of the perovskite, the quantum effect of the quantum points and multiple quantum wells formed by the perovskite and the quantum points, carriers are guided to the quantum wells with low potential barriers for recombination luminescence. In addition, crystal lattices of perovskite with different components are matched well; the perovskite composite LED with multiple quantum wells, compared with other quantum well structures, has few interface defects; and the non-radiative recombination centers are reduced efficiently.

The invention discloses an inorganic perovskite light emitting diode and a preparation method thereof. According to the method, a passivation layer (PVP) not only can improve the surface morphology ofthe perovskite and reduce the leakage current of the light emitting diode, but also can passivate surface defects of zinc oxide (ZnO), reduce the non-radiative recombination at the interface betweenthe perovskite and the zinc oxide and thus improve the radiative recombination efficiency, and can also improve the injection balance between electrons and holes at the same time. In addition, a composite perovskite light emitting material (Cs0.87MA0.13PbBr3) which is almost hole-free and very compact can be obtained by doping a small amount of MABr into CsPbBr3, thereby being also capable of effectively suppressing the generation of a non-radiative recombination center of elementary lead in CsPbBr3 while reducing the leakage current. The external quantum efficiency of the perovskite light emitting diode can be effectively improved according to the invention.

A design of a semiconductor saturable absorber that offers a convenient and reliable way to control/decrease the recovery time of the absorption. The absorption recovery time is controlled during the epitaxial growth by using lattice-mismatched layer(s) to induce dislocations, and implicitly non-radiative recombination centers within the nonlinear absorbing region. These lattice reformation layer(s) are interposed between the distributed Bragg reflector and the nonlinear absorption region, containing quantum-wells, quantum-dots or bulk semiconductor material. The thickness and composition of the lattice reformation layer(s) is an instrumental to control the amount of non-radiative recombination centers used to trap the optically excited carriers generated in the absorption region.

The invention discloses a light emitting diode and a manufacturing method thereof, and belongs to the technical field of a semiconductor. An electron baffle layer of the light emitting diode comprises three sub-layers, wherein the three sub-layers comprise a first sub-layer, a second sub-layer and a third sub-layer which are sequentially grown, the first sub-layer comprises an AlGaN/InGaN superlattice layer with (n+1) periods, the second sub-layer comprises an AlGaN/InGaN superlattice layer with n periods, the third sub-layer comprises an AlGaN/InGaN superlattice layer with (n-1) periods, InGaN layers in the first sub-layer, the second sub-layer and the third sub-layer are all doped with Mg, and n is more than or equal to 3 but less than or equal to 6. The electron baffle layers are divided into three superlattice sub-layers with different doping and same structure to form three segments of baffle layers, so that non-radiative recombination due to electrons leaked to a P layer is reduced as much as possible; and moreover, the periods of the superlattices of each sub-layer in the three sub-layers are gradually reduced according to 1, the electrons can be blocked better, meanwhile, not many holes can be blocked, and the luminous efficiency of a light emitting diode crystal is further improved.

The invention belongs to the semiconductor laser field. It comprises the following steps: cleaving the semiconductor laser to ropes in the air, then loading a fixture and putting it into an electron-beam vapor vacuum chamber; ion precleaning, that is to remove the oxidant and impurity substance in the cleaved cavity surface and the non-radiative recombination center as formed surface state and interface state with low energy ion current, which is less than 100eV , in the air of the electron-beam vapor vacuum chamber; ion precleaning the front cavity surface(4) for 30 seconds to 6 minutes; depositing broad forbidden band low absorbing material such as ZnSe or ZnS on the front cavity surface(4) to be an inactivating blocking layer(3) in the way of electron-beam vapor deposition; plating reflection reducting coating(1) on the front cavity surface(4); ion precleaning the rear cavity surface(5) from the back of the fixture for 30 seconds to 6 minutes; depositing ZnSe or ZnS on the rear cavity surface(5) in the way of electron-beam vapor deposition; plating high negative coating(2) on the rear cavity surface(5). The invented inactivating film is of stable performance, improved reliability, simple preparation, which can be used in lasers with different wave lengths or structures.

Two-dimensional (2D) transition-metal dichalcogenides have emerged as a promising material system for optoelectronic applications, but their primary figure-of-merit, the room-temperature photoluminescence quantum yield (QY) is extremely poor. The prototypical 2D material, MoS₂ is reported to have a maximum QY of 0.6% which indicates a considerable defect density. We report on an air-stable solution-based chemical treatment by an organic superacid which uniformly enhances the photoluminescence and minority carrier lifetime of MoS₂ monolayers by over two orders of magnitude. The treatment eliminates defect-mediated non-radiative recombination, thus resulting in a final QY of over 95% with a longest observed lifetime of 10.8±0.6 nanoseconds. Obtaining perfect optoelectronic monolayers opens the door for highly efficient light emitting diodes, lasers, and solar cells based on 2D materials.

The invention discloses a preparation method of a low-defect quasi-two-dimensional perovskite film based on methanesulfonic acid negative ion induction. According to the method, methanesulfonic acid (MeS) negative ions are led in an L2An-1MnX3n+1 perovskite precursor to adjust phase compositions, so that a more effective energy transfer way is generated. Crystal boundary and surface defect inactivation is achieved by the MeS negative ions, and non-radiative recombination is effectively restrained. The service life of an exciton of the prepared quasi-two-dimensional perovskite film is obviouslyprolonged, and three-dimensional perovskite crystal particles are obviously increased. CsMeS is added into quasi-two-dimensional metal halide perovskite precursor solution to adjust perovskite phasecompositions, so that more three-dimensional perovskite crystal particles are generated as compared with a traditional method, and the more effective energy transfer way is generated. According to themethod, mixing of perovskite crystal lattices in the used CsMeS is omitted, the crystal lattices only exist on the surfaces of the perovskite crystal lattices, crystal boundary and surface defect inactivation can be achieved by MeS negative ions in the CsMeS, and non-radiative recombination is effectively restrained.

The invention discloses a core-shell structured CuInS2/ZnS nanorod and a preparation method thereof. The preparation method comprises the steps of mixing indium chloride, cuprous chloride and lauryl mercaptan to obtain a CuInS2 nanorod; mixing and heating zinc fatty acid, lauryl mercaptan and 1-octadecene to obtain zinc fatty acid precursor; rapidly filling the obtained zinc fatty acid precursor into CuInS2 nanorod solution then slowly filling in the rest of the zinc fatty acid precursor for reaction; performing repeated dissolution and precipitation on reaction products and then performing centrifugal purification to obtain the core-shell structured CuInS2/ZnS nanorod. The core-shell structured CuInS2/ZnS nanorod obtains a large light energy absorbing section for linear polarized absorption and polarized emission and meanwhile can inhibit Auger non-radiative recombination and achieves relatively high illumination efficiency. Meanwhile, the high-quality core-shell structured CuInS2/ZnS nanorod can be applied to lighting and display.

The invention discloses a light-emitting enhancement type electron beam pumping ultraviolet light source and a preparation method thereof. According to the light-emitting enhancement type electron beam pumping ultraviolet light source and the preparation method thereof, multiple quantum wells of an epitaxial layer serve as an active region, a potential well adopts digital alloy of a monoatomic layer or a subatomic layer, carrier localization can be improved, non-radiative recombination process can be inhibited, and internal quantum efficiency can be further improved; a latticed reflecting layer with a concave surface is formed by utilizing periodic grid scratches and evaporating a highly-reflective metal thin film, reflection of ultraviolet light can be enhanced, and the light extraction efficiency can be increased; an electron beam pumping source adopts a field emission electron beam, and the miniaturization and low cost of the field emission electron beam are conductive to commercialization of the electron beam pumping source; meanwhile, the electron beam pumping source is equipped with a metal gate, is much easier in control of cathode accelerated current, and can effectively solve the problem of electron emission uniformity.

The invention discloses a Si-doped InAs/GaAs quantum dot laser and a preparation method thereof. The Si-doped InAs/GaAs quantum dot laser is characterized by comprising a quantum dot active region (50), wherein the quantum dot active region (50) comprises a Si-doped quantum dot layer (51); and according to the preparation method of the quantum dot laser, a buffer layer (20), a lower cladding layer(30), a lower waveguide layer (40), the quantum dot active region (50), an upper waveguide layer (60), an upper cladding layer (70) and an ohmic contact layer (80) are sequentially grown on a substrate (10) by adopting an MBE epitaxial growth method. According to the quantum dot laser, a non-radiative recombination center near quantum dots is effectively passivated through introducing Si atoms and the optical property of a quantum dot material is strengthened; and meanwhile, threshold current of a laser device can be reduced through electrons introduced by the Si atoms and the performance ofthe device can be improved.

A light-emitting device is optimized for radiative recombination and minimizes non-radiative recombination. The light-emitting device includes an emissive layer, a first electrode and a second electrode from which charges are generated, a first charge transport layer that injects charges from the first electrode into the emissive layer, and a second charge transport layer that injects charges from the second electrode into the emissive layer. At least one of the charge transport layers includes a mixture of a first nanoparticle population and a second nanoparticle population, and the first nanoparticle population and the second nanoparticle population are conductive nanoparticles that are energetically non-aligned as between the first nanoparticle population and the second nanoparticle population. Nanoparticles of the first nanoparticle population and the second nanoparticle population are energetically non-aligned with each other by being made of different materials, by having nanoparticles of different sizes, and/or by having nanoparticles of different shapes.

The invention discloses an epitaxial wafer of a GaN-based light-emitting diode and a preparing method of the epitaxial wafer, and belongs to the field of light-emitting diodes. The preparing method includes the steps that a substrate is provided; a buffer layer and an N-type layer sequentially grow on the substrate, an N-type current expanding layer, a multi-quantum-well layer and a P-type layer sequentially grow on the N-type layer, the N-type current expanding layer is a GaN layer adopting a delta doping technology for growth, the doping concentration of the N-type current expanding layer is smaller than that of the N-type layer, starting from one side of the N-type layer, the doping concentration of the N-type current expanding layer is kept unchanged or reduced gradually, and the doping concentration of the portion, adjacent to one side of the multi-quantum-well layer, of the N-type current expanding layer is zero. The current expanding layer grows by adopting the delta doping technology, the carrier concentration is high, compensation is small, and the device is good in heat stability; the undoped GaN layer is introduced into the position close to an active area to ensure transverse expansion of currents and reduce forward voltage drop, the service life is prolonged, and the fact that defects caused by doping extend to the active area and a non-radiative recombination center is reduced.