174 results about "Crystal growth rate" patented technology

A method for producing a nitride semiconductor, comprising controlling temperature and pressure in a autoclave containing a seed having a hexagonal crystal structure, a nitrogen element-containing solvent, a raw material substance containing a metal element of Group 13 of the Periodic Table, and a mineralizer so as to put said solvent into a supercritical state and/or a subcritical state and thereby ammonothermally grow a nitride semiconductor crystal on the surface of said seed, wherein the crystal growth rate in the m-axis direction on said seed is 1.5 times or more the crystal growth rate in the c-axis direction on said seed. By the method, a nitride semiconductor having a large-diameter C plane or a nitride semiconductor thick in the m-axis direction can be efficiently and simply produced.

Methods of crystal growth for semiconductor materials, such as nitride semiconductors, and methods of manufacturing semiconductor devices are provided. The method of crystal growth includes forming a number of island crystal regions during a first crystal growth phase and continuing growth of the island crystal regions during a second crystal growth phase while bonding of boundaries of the island crystal regions occurs. The second crystal growth phase can include a crystal growth rate that is higher than the crystal growth rate of the first crystal growth phase and/or a temperature that is lower than the first crystal growth phase. This can reduce the density of dislocations, thereby improving the performance and service life of a semiconductor device which is formed on a nitride semiconductor made in accordance with an embodiment of the present invention.

A SiC single crystal is produced by the solution growth method in which a seed crystal attached to a seed shaft is immersed in a solution of SiC dissolved in a melt of Si or a Si alloy and a SiC single crystal is allowed to grow on the seed crystal by gradually cooling the solution or by providing a temperature gradient therein. To this method, accelerated rotation of a crucible is applied by repeatedly accelerating to a prescribed rotational speed and holding at that speed and decelerating to a lower rotational speed or a 0 rotational speed. The rotational direction of the crucible may be reversed each acceleration. The seed shaft may also be rotated synchronously with the rotation of the crucible in the same or opposite rotational as the crucible. A large, good quality single crystal having no inclusions are produced with a high crystal growth rate.

The invention relates to a microwave synthesis process for a ZSM-11 molecular sieve. The process uses aluminum source, alkali source, silicon source, tetrabutylammonium bromide and de-ionized water as the raw materials and adopts the heating mode of microwave radiation. The reaction mixture is crystallized for 1 to 8 hours under microwave radiation and self-generated pressure at 130 to 180 DEG C, solid is separated from the mother liquid, and then the product is washed by the de-ionized water until the pH value is 8 to 9, thus obtaining the raw powder of the ZSM-11 molecular sieve. The microwave synthesis process for the ZSM-11 molecular sieve has the advantages of replacing traditional water heating by microwave radiation heating and obtaining the ZSM-11 molecular sieve with the advantages of high crystallinity, pure crystal phase and controllable and wide range of grain size, and the process accelerates the nucleation rate and crystal growth speed obviously and shortens the crystallization time greatly by pre-placing crystal seeds.

Affords Group III nitride crystals whose crystal growth rate is extensive, methods of their manufacture, and equipment for manufacturing such Group III nitride crystals. The manufacturing methods include: a melt-formation step, within a reaction vessel (21), of forming around a seed crystal (2) a melt (1) containing at least a Group III element and a catalyst; and a crystal-growth step of supplying a nitrogen-containing substance (3) to the melt (1) to grow a Group III nitride crystal (4) onto the seed crystal (2); characterized in controlling temperature so that in the crystal-growth step, the temperature of the melt (1) lowers from the interface (13) between the melt (1) and the nitrogen-containing substance (3), through to the interface (12) between the melt (1) and the seed crystal (2) or to the interface (14) between the melt (1) and the Group III nitride crystal (4) having grown onto the seed crystal (2).

Embodiments of the invention generally provide compositions of crystalline zeolite materials with tailored crystal habits and the methods for forming such crystalline zeolite materials. The methods for forming the crystalline zeolite materials include binding one or more zeolite growth modifiers (ZGMs) to the surface of a zeolite crystal, which results in the modification of crystal growth rates along different crystallographic directions, leading to the formation of zeolites having a tailored crystal habit. The improved properties enabled by the tailored crystal habit include a minimized crystal thickness, a shortened internal diffusion pathlength, and a greater step density as compared to a zeolite having the native crystal habit prepared by traditional processes. The tailored crystal habit provides the crystalline zeolite materials with an aspect ratio of about 4 or greater and crystal surfaces having a step density of about 25 steps/μm² or greater.

Embodiments of the invention generally provide compositions of crystalline zeolite materials with tailored crystal habits and the methods for forming such crystalline zeolite materials. The methods for forming the crystalline zeolite materials include binding one or more zeolite growth modifiers (ZGMs) to the surface of a zeolite crystal, which results in the modification of crystal growth rates along different crystallographic directions, leading to the formation of zeolites having a tailored crystal habit. The improved properties enabled by the tailored crystal habit include a minimized crystal thickness, a shortened internal diffusion pathlength, and a greater step density as compared to a zeolite having the native crystal habit prepared by traditional processes. The tailored crystal habit provides the crystalline zeolite materials with an aspect ratio of about 4 or greater and crystal surfaces having a step density of about 25 steps/μm² or greater.

The invention discloses a method for purifying dodecanedioic acid, which comprises the following steps of: carrying out demulsification, filtration and decoloration on stop fermentation liquor of dibasic acid and adding pure water to dilute; adding purified water into a crystallization kettle, pumping diluted fermented clear liquid into a crystallizer, simultaneously filling dilute sulphuric acid with the mass concentration of 30 percent into a discharge hole of an external circulating pump and adding the dilute sulphuric acid into the crystallizer, and controlling the PH of reaction materials; ensuring crystal mush to flow to the lower part of a crystallization chamber through a central downcomer and then flow upwards, so that crystals with large granularities are enriched on the bottom layer of the crystallization chamber; and cooling the crystals outflowing from a discharge hole of the crystallizer by a cooler and carrying out filter pressing, washing and drying to obtain the dodecanedioic acid. Due to the adoption of the purifying method, the micro mixing effect is achieved by diluting local concentration of the reaction mass through the material circulating pump, the solution nucleation rate, the crystal growth rate and the aggregation rate are reduced, the moisture percentage and the impurity content of a filter cake are obviously reduced, the dried dibasic acid product has large and uniform particles, good glossy and high purify, and the continuity of the crystallizing process is realized.

A process for closing hollow-core defects, called micropipes, during growth by CVD of a SiC crystal on a SiC single crystal substrate having hollow-core defects, and a crystal obtained according to the process, by contacting the SiC crystal with a source gas adjusted to a C/Si atom ratio range in which the crystal growth rate is determined by the carbon atom supply limitation, then epitaxially growing and laminating a plurality of SiC crystal layers, wherein hollow-core defects in the SiC single crystal substrate dissociate into a plurality of dislocations given by small Burgers vector in order not to propagate to the crystal surface. In addition, the present invention provides a fabrication process of a SiC crystal, wherein a first SiC crystal is made as a buffer layer, and a further SiC crystal is layered thereon using a source gas adjusted to be higher than that of the C/Si ratio when forming the buffer layer, whereby a desired film property is conferred.

The present invention provides a method and apparatus for growing a single crystal by the Czochralski method, wherein a single crystal is grown with forced cooling of neighborhood of a crystal growth interface by disposing a cooling cylinder formed of copper or a metal having a heat conductivity larger than that of copper at least in the vicinity of the crystal growth interface so as to surround the single crystal under pulling and circulating a cooling medium in the cooling cylinder. Thus, there are provided a method and apparatus for growing a single crystal, which can exert cooling effect on a growing single crystal to the maximum extent so as to realize higher crystal growth rate, even when a silicon single crystal having a diameter of 300 mm or more is grown.

The invention provides a flow guide cylinder for a monocrystal silicon growth furnace, which includes a tapered flow guide inner cylinder and a tapered flow guide outer cylinder, a heat preservation layer filled with heat preservation carbon felt is disposed therebetween. A heat insulation layer made from metal molybdenum or tungsten is disposed between the outer cylinder and the heat preservation layer. The tapered inner cylinder is used for absorbing radiation heat from a crystal ingot and then cooling the crystal ingot by means of gas rectifying to increase axial temperature gradient of the crystal ingot. Meanwhile, by means of the flow guide cylinder to rectify the gas, the flow speed of the gas is increased to reduce the partial pressure of SiO at liquid level of the melt, thereby reducing oxygen content in the melt. The flow guide cylinder can improve the quality of the crystal ingot, can accelerate growth of the crystal and can reduce production cost. The invention also provides an application method of eliminating polycrystal particles in quartz crucible walls by means of the flow guide cylinder.

The invention discloses an Al2O3-coated modified lithium nickel manganese oxide positive electrode material. A preparation method of the Al2O3-coated modified lithium nickel manganese oxide positive electrode material comprises the following steps of (1) preparing a solution; (2) dispersing lithium nickel manganese oxide into deionized water to form a turbid liquid and adding an anionic surfactant for ultrasonic dispersion for 15-30 minutes; (3) adding an Al(NO3)3 solution to an ultrasonic dispersed solution, carrying out ultrasonic dispersion for 15-30 minutes and then adding an NaAlO2 solution while stirring; (4) adding a citric acid solution of which the concentration is 0.5mol/L to the mixed solution obtained in the step (3) while stirring; (5) carrying out ageing, cleaning and drying; and (6) carrying out high-temperature pyrolysis. The crystal growth rate is consistent with the nucleation rate in the preparation process; coating is uniform; the prepared material is high in safety and low in cost; the energy density and the charge-discharge capacity at high voltage are obviously improved; and the capacity retention ratio reaches 86.3% after 500 charge-discharge cycles at a room temperature under the condition of 1C.

The invention discloses a silicon carbide crystal growth method for increasing a crystal growth rate. The silicon carbide crystal growth method specifically comprises the following steps: manufacturing a graphite column; filling silicon carbide powder resource into a crucible, and then inserting the graphite column into the silicon carbide powder resource, and placing the crucible assembly into a growth device; firing the silicon carbide powder resource and removing the impurities; taking the graphite column out of the crucible; and performing crystal growth operation. According to the silicon carbide crystal growth method, the problems of the prior art that the use ratio of the silicon carbide powder resource is not high and the average growth rate of the crystal is low are solved.

The invention provides a system and a control method for drawing a crystal bar. The system comprises: a first control unit which is used for controlling the drawing speed of the drawn crystal bar to be constant; an obtaining unit which is used for obtaining a distance between a solid-liquid interface and a reference surface, wherein the solid-liquid interface is an interface between a crystal liquid and the current crystal bar; a crucible used for containing the crystal liquid; a heating device used for heating the crucible; a second control unit used for adjusting the crucible lifting ratio under the condition that the distance is different from the preset distance in order to make the distance reach the preset distance, wherein the crucible lifting ratio is the ratio of the crystal growth rate to the crucible lifting rate; and a third control unit connected with the heating device and used for controlling the heating power of the heating device to make the diameter of the crystal barat each position is within a preset range. The system makes the ratio v/G of the drawing speed of the drawn crystal bar to the temperature gradient of the solid-liquid interface kept unchanged, so that the defect concentration of the drawn crystal bar is reduced.

The invention discloses a halide perovskite single crystal, a preparation method and application of the single crystal in preparation of an X-ray detector, and belongs to the technical field of X-raydetectors. The invention develops a method for controlling the growth of halide perovskite single crystals through solvent evaporation, the growth rate of the crystals is constant mainly by regulatingand controlling the growth temperature, the opening area of a solution and other factors, and the perovskite single crystals with lower crystal defect state density and higher carrier mobility-carrier lifetime deposition are grown. Polyoxyethylene is used for passivating surface defects of the perovskite single crystal, so that the crystal surface defects and surface leakage current are remarkably reduced, and the crystal has higher resistivity and lower noise current signals. The sensitivity of the prepared X-ray detector under 120 keV hard rays reaches 1274 [mu] C.Gyair.cm <2>, the lowest detection amount is as low as 0.56 [mu] Gyair.s <-1>, the requirements of medical imaging application are met, and the X-ray detector can be applied to metal material component analysis and flaw detection.

Preparation of lutetium and yttrium aluminate single crystals doped with rare earth oxides and transition elements consists in the preparation of oxide mixture sinter which is melted throughout and homogenized for a period of at least one hour. The crystal growth rate and broadening of the crystal cone are maintained uniform at an angle of at least 60° from the crystal axis up to a diameter of at least 80% of the crucible diameter which is at least 100 mm. The completion of the process occurs by separating the crystal from the melt while the crystal continues to be positioned inside the crucible in the zone wherein it was grown, and wherein final tempering of the crystal also takes place.

The invention relates to a method for growing an yttrium ferrite crystal by a guided mold pulling method, which comprises the following steps: placing a guided mold with internal longitudinal gaps in a crucible, adding polycrystal materials into the crucible, heating the crucible to melt the polycrystal materials, enabling the molten polycrystal materials to rise over the gaps at the bottom of the guided mold so as to enable the molten polycrystal materials to be raised to the top surface of the guided mold along the longitudinal gaps in the guided mold under the capillary effect, then dropping seed crystals, and finally pulling to obtain the yttrium ferrite single crystal. The invention can prepare large-size yttrium ferrite single crystals, simplify the post processing procedure of the crystal and lower the preparation cost of the crystal, and has the advantages of high crystal growing speed and good optical uniformity of the prepared crystal, thereby solving the problem that the pulling method can not be used for preparing large-size single crystals.

The invention relates to a method for growing a terbium-aluminum garnet crystal by using a guide die pulling method, comprising the following steps of: placing a guide die internally provided with a longitudinal gap into a crucible; adding a polycrystal raw material into the crucible; heating the crucible to melt the polycrystal raw material; immersing a molten mass of the polycrystal raw material into a gap at the lower part of the guide die so as to raise the molten mass of the polycrystal raw material to an upper surface of the guide die under the action of capillary effect along the longitudinal gap of the guide die; and then pulling a lower seed crystal into a single crystal consistent with the shape of the guide die. By the invention, a large-size terbium-aluminum garnet single crystal can be prepared, post processing procedures can be simultaneously simplified and the cost for preparing the crystal can be reduced; in addition, the growth speed of the crystal is high, the optical homogeneity of the prepared crystal is favorable and the problem that a large-size body single crystal is not difficult to prepare by adopting a pulling method can be solved.

The invention relates to a method for growing CaxBa1-xNb2O6 series crystals, belonging to the field of crystal growth. The method comprises the following steps: mixing powder CaCO3, BaCO3 and Nb2O5 according to the stoichiometric proportion of CaxBa1-xNb2O6, carrying out ball milling, baking, and passing through a 200-mesh screen, wherein x=0.22, 0.25, 0.28, 0.32 or 0.35; presintering, carrying out ball milling again, baking, and passing through a 80-mesh screen; putting the powder in an elongated rubber balloon, compacting, sealing, and vacuumizing to prepare a biscuit rod with uniform thickness and density under isopressing conditions; sintering the biscuit rod in a dip-coating rotary sintering furnace to obtain a compact and uniform polycrystal rod; putting the polycrystal rod in a floating region furnace, and heating at 60-100 DEG C/minute until the rod and seed crystals are molten, and abutting; and after setting the crystal growth rate at 2-5mm/hour, starting growth, and coolingto room temperature. The invention grows a CaxBa1-xNb2O6 crystal, which is 6-8mm in diameter 50-115mm long and does not have macroscopic defects, by an optical floating region process, has the advantages of high crystallization quality and high efficiency, and simplifies the technique.