30results about How to "Reduce growth stress" patented technology

The invention provides a method for growing silicon carbide crystals by a PVT method and a device thereof. The method comprises the following steps: (1) an assembling stage; (2) a heating stage: placing the assembled crucible in a furnace body, heating the crucible, and controlling the temperature difference between the temperature of the center of the top end of the crucible and the temperature of the edge of the top end of the crucible to be delta T1; and (3) a crystal growth stage: keeping the temperature of the center of the top end of the crucible unchanged, controlling the thermal insulation cover to move upwards along the side wall of the thermal insulation cylinder, and controlling the temperature difference between the temperature of the center of the top end of the crucible and the temperature of the edge of the top end of the crucible to be reduced to T2, so that the silicon carbide raw material is conveyed to the seed crystal for crystal growth in a gas phase manner. By controlling the heat preservation cover to move upwards, the annular temperature field is more uniform and stable, and the radial temperature gradient is gradually and slowly reduced to delta T2, so that directional quantitative adjustment of the radial temperature gradient is realized, the radial temperature gradient at the seed crystal is gradually reduced, the difference between the minimum thickness of the center and the minimum thickness of the edge of the silicon carbide crystal is reduced, and the effective utilization rate of the silicon carbide crystal with the same weight is increased.

The invention discloses a method for cooperative control of microcystis aeruginosa by using chub, bighead, silver xenocypris fish and daphnia magna, and belongs to the technical field of water treatment. The microcystis aeruginosa in water is controlled through a food chain relationship; the chub, the bighead, the silver xenocypris fish and the daphnia magna can directly eat the microcystis aeruginosa in a filtering manner; meanwhile, the chub, the bighead and the silver xenocypris fish also can intake the daphnia magna, so as to indirectly consume the microcystis aeruginosa in water; the fish, the daphnia magna and the microcystis aeruginosa form the food chain relationship. In addition, the upper, middle and lower microcystis aeruginosa and a microcystis aeruginosa resting body at the bottom can be controlled by fully utilizing the vertical spatial distribution difference of the three fishes in the water, the content of the microcystis aeruginosa in the water can be more effectively controlled, the eutrophication level is reduced, the balance of an ecological system of the water is facilitated, and meanwhile, certain economic value can be obtained by catching the chub, the bighead, the silver xenocypris fish. The method has the advantages of low cost, no secondary pollution and the like, and is simple and feasible.

The invention discloses a method for growing a high-quality aluminum nitride single crystal. In the method, the initial deposition layer adopts a large aluminum nitride / silicon carbide mixed filler mode, and then high-purity aluminum nitride powder is used, and the temperature changes during the growth process. The aluminum nitride filler layer in the crucible is from bottom to top. The first layer is the aluminum nitride powder layer, the second layer is the sintered aluminum nitride particle layer, and the third layer is the particle mixture of aluminum nitride and silicon carbide. material, and the fourth layer is a source of particle mixture of aluminum nitride and silicon carbide. In the present invention, by doping silicon carbide powder in aluminum nitride powder, different silicon carbide: aluminum nitride ratios are used in different interlayers to relieve the growth stress between the silicon carbide substrate and the aluminum nitride single crystal, and to grow In the process, the process of variable temperature and pressure is adopted to control the heating and cooling speed. The source body is from top to bottom, and the silicon carbide composition gradually decreases. By adjusting the concentration of silicon carbide in the source, the silicon carbide in the aluminum nitride single crystal is adjusted. content, so as to reduce the growth stress of aluminum nitride single crystal.

The invention relates to a control method for eliminating a spot defect of a moderately thick plate and belongs to the technical field of metallurgy. The method comprises the following steps of (1) a heating stage: carrying out high pressure water phosphorus removal after heating a continuous cast slab through controlling a heating coefficient; (2) a rolling stage: carrying out multi-pass high pressure water phosphorus removal in a hot rolling process; and (3) a cooling stage: cooling a hot rolled plate in an ultrafast cooling and laminar cooling combined way to prepare the moderately thick plate. Through the control on the temperature and the atmosphere in the heating stage, the matching of the rolling temperature and a phosphorus removal process in the rolling process and the combination of the ultrafast cooling and laminar cooling ways in the cooling stage in the control method disclosed by the invention, the straightness of an iron oxide scale and an interface is obviously increased; and no residual iron oxide scales are remained on the surface of a steel plate through subsequent sand blasting and shot blasting, so that the generation of the spot defect is effectively inhibited, and the surface quality of the moderately thick plate is obviously improved.

The invention discloses a preparation method of a low-stress TiW film. The method comprises the following steps: growing a thin seed film layer at a small deposition rate and growing a main film layer under a large deposition rate on a substrate of the film to be deposited; by controlling the thickness of the growth and rate, so that the two layers of films can be optimally combined, and a low-stress TiW film can be obtained. In the invention, the TiW film is deposited on the substrate step by step, the seed film layer grown at a small deposition rate has high density, and a highly reliable interface is obtained by mutual fusion with the substrate atoms; the main film layer grown at a large deposition rate is The adhesion of the film grown on the basis of the seed layer buffer is enhanced, so that the thickness of the TiW film is stable and uniform, and the stress on the substrate is weakened and dissipated, so that the deformation amount is small, and the preparation method of the TiW film with low stress and high quality is obtained. The TiW thin film of the present invention can be prepared by common deposition methods, the obtained thin film has high stability, low film layer stress, and has good usability and popularization.

The invention discloses a fabrication method of a chip. A transition substrate in lattice matching of a target epitaxial layer is employed, and a transition epitaxial layer with an integral crystal structure can be formed on a surface of the transition substrate by an epitaxial process; since the transition epitaxial layer is of the integral crystal structure, the target epitaxial layer with a single-crystal structure can be formed on a target substrate which is not in lattice matching by the epitaxial process and by taking the transition epitaxial layer as a target material; since the targetepitaxial layer is of the single-crystal structure formed by the epitaxial process, the thickness accuracy of the target epitaxial layer is relatively good, the growth stress with the target substrateis relatively small, a new substrate is not needed to be laminated so as to perform substrate transferring, the problems of relatively poor growth thickness accuracy and relatively large lamination stress and growth stress of the epitaxial layer in the prior art are solved, and the reliability of an LED chip is improved.

The invention discloses a fabrication method of a chip. A transition substrate in lattice matching of a target epitaxial layer is employed, and a transition epitaxial layer with an integral crystal structure can be formed on a surface of the transition substrate by an epitaxial process; since the transition epitaxial layer is of the integral crystal structure, the target epitaxial layer with a single-crystal structure can be formed on a target substrate which is not in lattice matching by the epitaxial process and by taking the transition epitaxial layer as a target material; since the targetepitaxial layer is of the single-crystal structure formed by the epitaxial process, the thickness accuracy of the target epitaxial layer is relatively good, the growth stress with the target substrateis relatively small, a new substrate is not needed to be laminated so as to perform substrate transferring, the problems of relatively poor growth thickness accuracy and relatively large lamination stress and growth stress of the epitaxial layer in the prior art are solved, and the reliability of an LED chip is improved.

The invention discloses a manufacturing method of a light emitting diode epitaxial wafer, and belongs to the technical field of semiconductors. The manufacturing method includes: sequentially growing a buffer layer, an undoped GaN layer, an N-type GaN layer, a stress release layer, an active layer, a P-type electron barrier layer and a P-type GaN layer on a substrate, wherein the growth pressure of the undoped GaN layer and the N-type GaN layer is 10-200torr. According to the manufacturing method, the growth pressure of the undoped GaN layer and the N-type GaN layer is limited to be10-200torr, so that the growth speeds of the undoped GaN layer and the N-type GaN layer are slow, and thereby heat can be uniformly transmitted along the growth direction of the epitaxial layer by a basal disc arranged at the bottom of the substrate, temperature difference between the upper and lower surfaces of the epitaxial wafer when the undoped GaN layer and the N-type GaN layer grow is reduced, the concave deformation of the epitaxial wafer is relieved, the temperature of the periphery of the epitaxial wafer can reach required temperature, and the quality of crystals at the periphery of the epitaxial wafer is improved.

The invention relates to the field of diamond manufacturing, in particular to a diamond growth tray and system. A diamond growth tray, comprising a base and a platform mounted on the base; the platform is in the shape of a regular polygonal prism or a circular truncated shape, and has a groove on the upper surface, and the edge of the opening of the groove is inverted corner design. Compared with the existing technology, it has the following effects: through the newly designed seed crystal tray, the plasma distribution and electric field distribution on the surface of the seed crystal can be maintained in the best state, ensuring a stable growth environment for the diamond seed crystal, reducing the number of surface growth defects, Finally, a high-quality single crystal diamond sheet is synthesized; through the newly designed seed tray, the growth rate of impurities such as carbon black on the edge of the seed tray can be significantly reduced, ensuring a longer stable growth time for a single time, and thicker diamonds can be grown at one time products and improve production efficiency.

The invention discloses a growing method of a GaN-based light emitting diode epitaxial wafer, and the growing method belongs to the technical field of semiconductors. The growing method comprises the steps of: providing a substrate; and successively growing a buffer layer, an un-doped GaN layer, an n-type layer, a stress release layer, a multi-quantum well layer, a p-type electron blocking layer, a p-type layer and a p-type contact layer on the substrate, wherein the stress release layer comprises a first sub-layer, a second sub-layer and a third sub-layer which are successively grown on the n-type layer, the first sub-layer is an In<x>Ga<1-x>N layer doped with Si, 0<=x<1, the second sub-layer comprises In<y>Ga<1-y>N layers and GaN layers which are laminated alternately, 0<y<1, the third sub-layer is an In<z>Ga<1-z>N layer doped with Si, 0<=z<1, the growth pressure of the second sub-layer is lower than that of the first sub-layer, and the growth pressure of the third sub-layer is lower than that of the first sub-layer. The growing method of the GaN-based light emitting diode epitaxial wafer improves the warping degree and enhances the crystal quality and the photoelectric performance.

The invention provides a method and device for growing silicon carbide crystal by PVT method. The method includes: (1) an assembly stage; (2) a heating stage: the assembled crucible is placed in a furnace body, and the crucible is heated, The temperature difference between the temperature at the center of the top of the crucible and the edge of the top of the crucible is controlled to be ΔT1; (3) Crystal growth stage: keep the temperature at the center of the top of the crucible unchanged, control the heat preservation cover to move up along the side wall of the heat preservation cylinder, and control the center of the top of the crucible at the same time. The temperature difference between the temperature of the crucible and the top edge of the crucible is reduced to ΔT2, so that the silicon carbide raw material gas phase is transferred to the seed crystal for crystal growth. By controlling the upward movement of the heat preservation cover, the annular temperature field is more uniform and stable, and the radial temperature gradient gradually decreases to ΔT2, realizing the directional quantitative adjustment of the radial temperature gradient, gradually reducing the radial temperature gradient at the seed crystal, and reducing the size of the silicon carbide. The difference between the minimum thickness of the center and the edge of the crystal increases the effective utilization of the same weight of silicon carbide crystal.

The invention relates to the field of scintillation crystal materials, a multi-ion doped large-size lanthanum bromide single crystal scintillator, characterized in that: the general chemical formula of the single crystal scintillator is (CexSryHfy)La(1-x-2y )Br3, where 0.001

The invention discloses a double-layer thermal barrier / high-temperature low-infrared emissivity integrated coating. The coating is a multi-layer superimposed structure, and the multi-layer superimposed structure sequentially includes a metal bonding layer and a thermal barrier ceramic from the inside to the outside. Inner layer, thermal barrier ceramic outer layer and low infrared emissivity layer, the thermal barrier ceramic inner layer is La 2 Zr 2 o 7 ‑8YSZ mixture layer, where La 2 Zr 2 o 7 The powder accounts for no more than 45% of the mass fraction of the mixture, the outer layer of the thermal barrier ceramic is a rare earth zirconate layer, and the low infrared emissivity layer is a Bi 2 o 3 ‑Al 2 o 3 -ZrO 2 ‑CaO‑SiO 2 Department of glass coating. The invention also provides a coated metal composite material and a preparation method thereof. The integrated coating of the invention has the characteristics of heat insulation performance, low infrared emissivity at high temperature, excellent thermal shock resistance and the like.

The invention discloses a manufacturing method of a light-emitting diode epitaxial wafer and the light-emitting diode epitaxial wafer, and belongs to the field of light-emitting diodes. The method comprises the steps as follows: a substrate is provided; and a low-temperature buffer layer, a high-temperature buffer layer, an N-type layer, an active layer, an electron blocking layer and a P-type layer sequentially grow on the substrate. The manufacturing method is characterized in that the P-type layer grows as follows: a first GaN sub-layer with a first thickness and a first Mg doping concentration grows on the electron blocking layer at a first growth temperature, a first growth pressure and a first growth rate; a second GaN sub-layer with a second thickness and a second Mg doping concentration grows on the first GaN sub-layer at a second growth temperature, a second growth pressure and a second growth rate; and a third GaN sub-layer with a third thickness and a third Mg doping concentration grows on the second GaN sub-layer at a third growth temperature, a third growth pressure and a third growth rate.

The invention relates to a growth method for controlling the grain size of polycrystalline diamond by a microwave CVD method, which comprises the following steps: in a deposition process, setting N groups of time periods, and continuously introducing mixed gases with different volume ratios into each group of time periods after the first group of time periods; along with the increase of the time periods, enabling the volume ratio of each gas in the mixed gas introduced after the N group of time periods to be higher than the volume ratio of the corresponding gas introduced after the (N-1) group of time periods; and after the N group of time periods, continuously introducing the mixed gas based on the volume ratio of each gas in the mixed gas until the growth is finished. According to the method, the carbon source concentration and the oxygen concentration are gradually increased in different time periods, the nucleation rate of the diamond is stepwise increased to control the grain size of the diamond, and therefore the quality of a diamond film is improved; meanwhile, the growth rate of the diamond film can be increased step by step, and lattice defects of the epitaxial layer are reduced, so that the growth stress can be reduced, and the complete crack-free diamond film can be obtained.