55results about How to "Reduce Mismatch Problems" patented technology

The invention discloses a C/C composite material superhigh temperature ceramic coating, and a preparation method thereof. The C/C composite material superhigh temperature ceramic coating is composed of an anti-oxidation SiC transition internal layer and a superhigh temperature ablation-resistant ceramic external layer; the superhigh temperature ablation-resistant ceramic external layer is composedof more than one ingredients selected from SiC, ZrC, HfC, TaC, TiC, ZrB2, HfB2, TaB2, and TiB2. The preparation method is suitable for industrialized production, is simple in equipment, is convenientin operation, is capable of controlling coating thickness, satisfying preparation requirements of large size C/C composite material superhigh temperature ceramic coating with complex shapes, and is asuperhigh temperature ceramic coating preparation method with excellent development potential.

The invention discloses a light-emitting diode with a composite polar face electron blocking layer. The light-emitting diode comprises a substrate (101), a metal polar face n-type nitride layer (102), a metal polar face multiple quantum well layer (103), a metal polar face p-type nitride layer (104), a composite polar face p-type electron blocking layer (105) composed of a metal polar face p-type electron blocking layer (1051) and a nitrogen polar face p-type electron blocking layer (1052), a nitrogen polar face p-type nitride layer (106), an n electrode (7) arranged on the metal polar face n-type nitride layer and a p electrode (8) arranged on the nitrogen polar face p-type nitride layer, and the layers and the electrodes are arranged sequentially from bottom to top. A high electronic barrier is formed on a conduction band by the composite polar face electron blocking layer and blocks electrons from crossing a multiple quantum well active region to enter a p-type region, leakage currents can be reduced, and the probability of radiative recombination of the electrons and holes is improved.

The invention relates to a ceramic modification C/C composite material with a ceramic coating layer and a preparation method thereof. The preparation method of the ceramic modification C/C composite material comprises the following steps of performing density increase on a carbon fiber prefabricated body by a chemical vapor deposition process to obtain C/C porous bodies; performing more than once soaking-cracking process on the C/C porous body until the density of the ceramic modification C/C composite material reaches 1.8g/cm<3> or higher; obtaining the ceramic modification C/C composite material. According to the preparation method of the C/C composite material with the ceramic coating, a ceramic outer coating layer is mainly prepared on the surface of the ceramic modification C/C composite material. The method solves the problem of heat expansion coefficient unbalance of the base body and the coating, and has the advantages that the equipment and the process are simple; the operation is easy; the coating structure content is controllable; large-dimension and complicated-shape special-shaped workpieces can be prepared, and the like; great engineering application potential is realized.

The invention discloses a light emitting diode epitaxial wafer and a fabrication method thereof, and belongs to the technical field of semiconductors. The fabrication method comprises the steps of providing a patterned sapphire substrate (PSS); forming an aluminum nitride buffer layer on a surface, on which patterns are arranged, of the PPS, wherein the aluminum nitride buffer layer comprises first parts and second parts, the first parts are arranged on the patterns, the second parts are arranged among the patterns; coating photoresist on the aluminum nitride buffer layer, wherein the thickness of the photoresist arranged on the first parts is smaller than the thickness of the photoresist arranged on the second parts; performing dry etching on the photoresist until the photoresist arranged at the tops of the first parts is removed; removing the tops of the first parts; laying a silicon dioxide material; removing the residual photoresist to form a silicon dioxide layered structure; and sequentially growing an N-type gallium nitride layer, a light emitting layer and a P-type gallium nitride layer. By the fabrication method, the epitaxial defect of a top end of the PPS caused by the aluminum nitride buffer layer can be prevented, and lattice mismatching also can be buffered by the aluminum nitride buffer layer.

The invention belongs to the field of semiconductor image sensing, and specifically relates to a digital correction method for an array analog to digital converter of a high-performance CMOS image sensor. The invention provides an algorithm based on a multi-way collaborative digital correction technology. In particular, for the features that the number of the ADCs in the array ADC of the CIS is high, the area of a single ADC is very small and capacitance mismatch is high, according to the algorithm, an analog to digital converter array which is applied to the CIS and is realized by matching with the algorithm fully is designed. A low working voltage of 1.8V is employed in the integral design. The pixel voltage of the image sensor passes through a variable gain amplifier (VGA), then is directly sent to the analog to the digital converter (ADC) array for conversion, and then is sent to a digital correction engine for calculation. The array analog to digital converter applied to the CMOS image sensor is taken as an integral system. The mismatch problem due to the fact that the area of the single analog to digital converter of the array analog to digital converter is small is reduced to a great extent. According to the multi-way collaborative digital correction technology of the array analog to digital converter applied to the CMOS image sensor provided by the invention, the integral performance of the array analog to digital converter can be effectively improved.

The invention relates to a reaction diffusion connection method of ceramic composite material and metal, which belongs to the technical field of connection of ceramic material and metal material, and is characterized in that corresponding mixed powder is added between the ceramic composite material and the metal, combustion reaction heat is generated under the activation of an electric field, and the ceramic composite material and the metal material are locally smelted respectively and generate diffusion reaction to form connection. The combustion synthesis of the metal powder forms an intermetallic compound with the performance between ceramic and metal, thus alleviating the problem of mismatching between the metal and the ceramic; and the action of the electric field causes elements between interfaces to diffuse mutually, thus being beneficial to improving the strength of the connecting interfaces. By combustion heat release, the method realizes the synthesis of an intermediate layer and the connection of metal and ceramic simultaneously, and has the characteristics of being low in energy consumption and high in connection strength.

The invention discloses a self-adaptive air filtering method based on iterative shrinkage weighted fusion. The method comprises the steps that an array antenna receives data to build a signal model, and a sampling covariance matrix of the received data is obtained; a self-adaptive iteration way is adopted to update a priori covariance matrix on line; weighting coefficients of the sampling covariance matrix and the priori covariance matrix are calculated according to the minimum mean-squared error criterion, and an estimated covariance matrix is obtained through the shrinkage weighted fusion processing method; finally, the self-adaptive weight vector is calculated to carry out air filtering. The self-adaptive air filtering method can estimate the covariance matrixes with high precision on the condition of small samples, can effectively relieve the priori knowledge and current data model mismatch problem, avoids subspace dimensionality determination, has the advantages of being high in output signal to interference plus noise power ratio and convergence rate, and is effective for self-adaptive air filtering actual application.

The invention provides an LED epitaxial wafer and a preparation method thereof, the LED epitaxial wafer comprises a substrate, and a low-temperature buffer layer, a three-dimensional growth layer, a two-dimensional growth layer and a GaN layer which are grown on the substrate in sequence, and the two-dimensional growth layer comprises a first sub-layer, a second sub-layer and a third sub-layer which are grown in sequence; wherein the first sub-layer is a periodic composite layer formed by repeatedly overlapping an AlGaN layer and a BGaN layer, the second sub-layer is a growth pause layer, and the third sub-layer is a periodic composite layer formed by repeatedly overlapping and growing a BN layer and an SiN layer. According to the LED epitaxial wafer, the two-dimensional growth layer is specially designed, and the composite two-dimensional growth layer is adopted, so that the LED epitaxial wafer which is higher in surface flatness, smaller in dislocation density, better in antistatic capacity, few in defect extending to a quantum well and improved in luminous intensity can be obtained.

The invention relates to a JPEG image mismatch steganography analysis method based on heterogeneous characteristic subspace migration. The method provided by the invention takes characteristics of different fields as a combination of domain-independent and domain-related characteristic subspaces, and the method comprises the following steps: firstly providing a low-rank constrained domain-independent characteristic migration method, and realizing local information migration by utilizing local data characteristics between different fields; secondly, based on sparse representation of modeling domain-related characteristics, measuring influence produced by field change on the modeling domain-related characteristics; and finally, by virtue of the steps, constructing an objective function, andsolving by virtue of an imprecise augmented Lagrange multiplier method. Unique global information of the domain-related characteristics is considered while local information migration is realized in adomain-independent characteristic subspace, so that characteristic differentiation degree between a cover image and a stego image can be improved, detection effect of mismatch steganography analysiscan be beneficially improved, and great significance is produced to the mismatch steganography analysis.

The invention provides a nitride light-emitting diode structure and a preparation method. The preparation method comprises the following steps: providing a glass substrate; stacking a buffer layer structure on the glass substrate, wherein the buffer layer structure is composed of cycles of SiAlN layers and AlGaN layers, and the number of cycles is 1-5; and then, growing a non-doped gallium nitride layer, an N-type layer, a quantum well structure layer and a P-type layer sequentially. According to the invention, the substrate is made of glass which is cheap and technologically mature, and the SiAlN and AlGaN buffer layer is grown on the substrate. Therefore, the constant of lattice mismatch between the substrate and an epitaxial layer is improved, and the photoelectric performance of light-emitting diodes is improved.

The invention discloses a light emitting diode epitaxial wafer and a preparation method thereof, which belong to the field of light emitting diode manufacturing. The AlGaN sub-layers and the first GaNsub-layers which are alternately stacked can release certain stress in the growth process, and dislocation defects accumulated in the first composite layer are few. The buffer layer further comprisesa second composite layer stacked on the first composite layer, and the structure of the second composite layer can be a second GaN sub-layer and a MgN sub-layer which are alternately stacked, and a second GaN sub-layer and a BN sub-layer which are alternately stacked. The Mg atoms and B atoms in the BN sub-layer are small in particle size, vacancies generated by defects and dislocations in crystals can be filled in the growth process, so that the formation of the dislocations and the defects is reduced, the crystal quality of the buffer layer is improved, and the luminous efficiency of the finally obtained light-emitting diode epitaxial wafer is also improved.

An epitaxial structure of a Si-based gallium nitride device belongs to the technical field of microelectronics. The epitaxial structure comprises a substrate, a nucleating layer, a buffer layer, a high-resistance layer, a channel layer and a barrier layer which are sequentially stacked from bottom to top, wherein the nucleating layer is formed by ALN/GaN cyclic growth, and the buffer layer is formed by InN/SiN/GaN in a cyclic growth mode and comprises an InN crystal nucleus layer, a reticular structure SiN thin layer and a GaN filling layer. According to the invention, the ALN/GaN nucleating layer is circularly grown to relieve lattice mismatch and thermal mismatch of the substrate and the epitaxial layer, and the InN/SiN/GaN buffer layer can greatly reduce the dislocation density of the material and improve the lattice quality, thereby improving the electron mobility, breakdown voltage, leakage current and other characteristics of the HEMT device.

The invention discloses a surface treatment method of a graphite substrate and a preparation method of a TaC coating, and the surface treatment method comprises the following steps: cleaning and drying the graphite substrate, putting the graphite substrate into a reaction chamber of plasma modification equipment, closing an air inlet valve, vacuumizing the reaction chamber, and then introducing oxygen or argon to fill the reaction chamber; adjusting the air inlet valve to stabilize the vacuum degree of the reaction chamber at 10-100Pa, starting to discharge a radio frequency power supply, andperforming oxygen plasma or argon plasma to bombard the surface of the graphite substrate so as to increase the roughness of the surface of the graphite substrate and improve the activity of the surface of the graphite substrate; and performing TaC coating deposition after treatment by the method. The formed TaC coating can be tightly combined with a graphite substrate and is not easy to fall off,and the thermal shock resistance is greatly improved; and the process is simple, efficient, low in energy consumption, low in production cost and short in production period.

The invention discloses a method for growing a gallium nitride film on a silicon substrate. According to the method for growing the gallium nitride film on the silicon substrate, a nitride composite buffer layer is epitaxially grown on the Si substrate, and the nitride composite buffer layer can relieve lattice mismatch and prevent a reflow etching reaction. A group of superlattices are grown on aGaN transition layer, and the superlattices can release part of tensile stress and can filter part of threading dislocation. By adopting the method, the crystal quality of a GaN epitaxial film material can be significantly improved, surface cracks are eliminated, and the GaN epitaxial film material which can be used for device development and application is obtained.

The invention relates to a W type antimony-based semiconductor laser with gradually varied Ga In proportion, which belongs to the technical field of semiconductor lasers. The existing InAs/GaInSb W type antimony-based semiconductor laser is difficult to realize luminescence at room temperature, and is less in output power of luminescence at low temperature (73K). The W type antimony-based semiconductor laser with gradually varied Ga In proportion sequentially comprises a GaSb substrate, a GaSb buffer layer, a P type GaSb contact layer, a P type quantum well, an intrinsic quantum well, an N type quantum well and an N type InAs contact layer from bottom to top, wherein the P type quantum well, the intrinsic quantum well and the N type quantum well respectively have a multi-period structure; the structure of each single-period quantum well in each multi-period structure is a sandwich structure that a GaInSb hole quantum well is clamped by double InAs electronic quantum wells; the outer layer is a pair of AlSb alloy limiting layers. The W type antimony-based semiconductor laser with gradually varied Ga In proportion is characterized in that the GaInSb hole quantum well is formed by 3 to 9 layers of Ga1-xInxSb layers, wherein x is equal to 0.05-0.35; the value of x of the Ga1-xInxSb layer in the middle is maximal; the Ga1-xInxSb layers on two sides are distributed in 1 to 4 levels from the middle to two sides; the values of x of two Ga1-xInxSb layers at the same level are the same, and the values of x of the Ga1-xInxSb layers from the middle to two sides are gradually reduced.

The invention discloses an epitaxial wafer of a light-emitting diode and a preparation method of the epitaxial wafer and belongs to the field of semiconductor optoelectronics. According to the method,an Al<x>Ga<1-x>N layer and an Al<y>Ga<1.5y>In<1-2.5y>N layer are sequentially arranged between an AlN layer and an undoped GaN layer, Al components in the Al<x>Ga<1-x>N layer and the Al<y>Ga<1.5y>In<1-2.5y>N layer can be within the ranges of 0.4<=x<=1 and 0.2<=y<=0.4, and when the Al components in the Al<x>Ga<1-x>N layer and the Al<y>Ga<1.5y>In<1-2.5y>N layer are within the ranges, lattice mismatch between the AlN layer and the undoped GaN layer can be relieved. Moreover, the Al component in the Al<x>Ga<1-x>N layer and the Al component in the Al<y>Ga<1.5y>In<1-2.5y>N layer are both graduallyreduced along the growing directions of the two layers, the Al components in the two layers are equal at the interface of the two layers, therefore, connection of the AlN layer and the undoped GaN layer can be well realized, defects generated due to lattice mismatch between the AlN layer and the undoped GaN layer are reduced, the crystal quality of the epitaxial wafer of the finally obtained light-emitting diode is improved, and the luminous efficiency of the finally obtained light-emitting diode is improved.

The invention provides a semiconductor HEMT device and a manufacturing method thereof. The semiconductor HEMT device comprises: a substrate; a heat conduction layer which is located on the surface of one side of the substrate, and comprises a plurality of supporting structures arranged at intervals and a heat conduction structure, wherein the supporting structures are located on the surface of one side of the substrate; the heat conduction structure is located on the surface, on the same side as the supporting structures, of the substrate, and gaps among the multiple supporting structures are filled with the heat conduction structure; and an insulating layer which covers the surface of the side, back to the substrate, of the heat conduction structure, and further covers the surfaces of the sides, back to the substrate, of the multiple supporting structures, wherein the heat conduction structure is a carbon film. According to the semiconductor HEMT device, through the arrangement of the heat conduction layer, stress concentration caused by thermal mismatch of the device can be reduced, and the possibility of cracking of the device is reduced.