266 results about "Bulk crystal" patented technology

A method and apparatus for producing bulk single crystals of AlN includes a crystal growth enclosure with Al and N2 source material therein, capable of forming bulk crystals. The apparatus maintains the N2 partial pressure at greater than stoichiometric pressure relative to the Al within the crystal growth enclosure, while maintaining the total vapor pressure in the crystal growth enclosure at super-atmospheric pressure. At least one nucleation site is provided in the crystal growth enclosure, and provision is made for cooling the nucleation site relative to other locations in crystal growth enclosure. The Al and N2 vapor is then deposited to grow single crystalline AlN at the nucleation site.

A new method is disclosed for the exfoliation of hexagonal boron nitride into mono- and few-layered nanosheets (or nanoplatelets, nanomesh, nanoribbons). The method does not necessarily require high temperature or vacuum, but uses commercially available h-BN powders (or those derived from these materials, bulk crystals) and only requires wet chemical processing. The method is facile, cost efficient, and scalable. The resultant exfoliated h-BN is dispersible in an organic solvent or water thus amenable for solution processing for unique microelectronic or composite applications.

A production method is provided in which Group-III-element nitride single crystals that have a lower dislocation density and a uniform thickness and are transparent, high quality, large, and bulk crystals can be produced with a high yield. The method for producing Group-III-element nitride single crystals includes: heating a reaction vessel containing at least one metal element selected from the group consisting of an alkali metal and an alkaline-earth metal and at least one Group III element selected from the group consisting of gallium (Ga), aluminum (Al), and indium (In) to prepare a flux of the metal element; and feeding nitrogen-containing gas into the reaction vessel and thereby allowing the Group III element and nitrogen to react with each other in the flux to grow Group-III-element nitride single crystals, wherein the single crystals are grown, with the flux being stirred by rocking the reaction vessel, for instance.

This invention relates to use of metamaterials for creating spectral selectors of electromagnetic radiation. Planar metamaterial films patterned on the sub-wavelength scale can be used in polarization filters instead of natural and synthesized bulk crystals. Characteristics and the quality factor of metamaterial filters is controlled by the geometry of the pattern. Various types of metamaterials and filter configurations are proposed.

A bulk, quasi-periodic phase-matched difference-frequency (DFG) process in field-poled LiNbO.sub.3 bulk crystal permits continuous tunability of the output radiation in the 3.0-4.1 .mu.m wavelength range through grating rotation. DFG in QPM-LiNbO.sub.3 crystal, carried out using a Nd:YAG laser and a high power semiconductor laser at the quasi-phased matching (QPM) degeneracy point, results in an ultra wide 0.5 .mu.m acceptance bandwidth, permitting crystal rotation-free wavelength tuning of 4.0-4.5 .mu.m, with 0.2 mW output power at 4.5 .mu.m.

The invention provides a method used for determining Bravais lattice of unknown crystal by electron backscatter diffraction. The invention is characterized in that the method comprises the steps as follows: 1) an electron backscatter diffraction spectrum is obtained and the crystal diffraction information in the diffraction spectrum is measured; 2) a two-dimensional reciprocal surface of the crystal is obtained; 3) a three-dimensional reciprocal primitive cell is reconstructed by the two-dimensional reciprocal surface; 4) the cell parameter of the three-dimensional reciprocal primitive cell s worked out according to the width of the Kikuchi band and the angle between the Kikuchi bands in the same Kikuchi electrode; 5) a reciprocal reduced cell of the crystal is solved; 6) the Bravais lattice of the crystal is determined in the reciprocal space; 7) the Bravais lattice of the crystal is determined. In the method, only a scanning electron microscope and an electron backscatter diffraction accessory are used to realize the analysis on unknown lattice of bulk crystals, and the exponential of the Kikuchi band and the Kikuchi electrode in the electron backscatter diffraction spectrum is marked at the same time. The method has no special requirement on the samples to be analyzed, is suitable for quickly analyzing bulk samples, and can be used for analyzing the microstructure morphologies and crystal structure in the buck samples.

A method capable of stably manufacturing a SiC single crystal in the form of a thin film or a bulk crystal having a low carrier density of at most 5×10¹⁷/cm³ and preferably less than 1×10¹⁷/cm³ and which is suitable for use in various devices by liquid phase growth using a SiC solution in which the solvent is a melt of a Si alloy employs a Si alloy having a composition which is expressed by Si_xCr_yTi_z wherein x, y, and z (each in atomic percent) satisfy

0.50<x<0.68, 0.08<y<0.35, and 0.08<z<0.35, or  (1)

0.40<x≦0.50, 0.15<y<0.40, and 0.15<z<0.35.  (2)

x, y, and z preferably satisfy 0.53<x<0.65, 0.1<y<0.3, and 0.1<z<0.3.

A method for producing a group III nitride crystal in the present invention includes the steps of cutting a plurality of group III nitride crystal substrates 10p and 10q having a main plane from a group III nitride bulk crystal 1, the main planes 10pm and 10qm having a plane orientation with an off-angle of five degrees or less with respect to a crystal-geometrically equivalent plane orientation selected from the group consisting of {20-21}, {20-2-1}, {22-41}, and {22-4-1}, transversely arranging the substrates 10p and 10q adjacent to each other such that the main planes 10pm and 10qm of the substrates 10p and 10q are parallel to each other and each [0001] direction of the substrates 10p and 10q coincides with each other, and growing a group III nitride crystal 20 on the main planes 10pm and 10qm of the substrates 10p and 10q.

A gallium nitride crystal with a polyhedron shape having exposed {10-10} m-planes and an exposed (000-1) N-polar c-plane, wherein a surface area of the exposed (000-1) N-polar c-plane is more than 10 mm² and a total surface area of the exposed {10-10} m-planes is larger than half of the surface area of (000-1) N-polar c-plane. The GaN bulk crystals were grown by an ammonothermal method with a higher temperature and temperature difference than is used conventionally, and using an autoclave having a high-pressure vessel with an upper region and a lower region. The temperature of the lower region of the high-pressure vessel is at or above 550° C., the temperature of the upper region of the high-pressure vessel is set at or above 500° C., and the temperature difference between the lower and upper regions is maintained at or above 30° C. GaN seed crystals having a longest dimension along the c-axis and exposed large area m-planes are used.

The invention relates to a europium rare earth metal-organic frame material and a preparation method and application thereof. The chemical formula of the product is {[Eu2(L)3(DMF)2]}n. The preparation method comprises the following steps: adding 5-(4-hydroxy-1,2,4-triazolyl)-4-benzene-1,3-dicarboxylic acid and europium chloride hexahydrate into a mixed solution of methanol and DMF, and stirring uniformly to obtain a mixed solution; then charging the mixed solution into a polytetrafluoroethylene lined hydrothermal synthesis high-pressure reaction kettle, cooling and filtering after reaction to obtain colorless bulk crystals; and then repetitively washing the colorless bulk crystals with the mixed solution of methanol and DMF to obtain the metal organic frame material. The europium rare earth metal-organic frame material has the advantages of simple preparation process, mild reaction conditions, high yield and low cost; and at room temperature, chlorobenzene, 1,2-dichlorobenzene, 1,2,4-trichlorobenzene, 1,2,3,4-tetrachlorobenzene, 1,2,4,5-tetrachlorobenzene, pentachlorobenzene and hexachlorobenzene have different degrees of fluorescence quenching responses on the material, and the material has good application prospects in environmental monitoring.

An electronically modulated prism, having a bulk crystal, a plurality of electrode pads formed on a top surface of the bulk crystal, and a common electrode formed on a bottom surface of the bulk crystal. The bulk crystal is optically isotropic with zero electric field applied thereto and optically anisotropic when subjected to a non-zero electric field. More specifically, the bulk crystal between each of the electrode pads and the common electrode has an index of fraction altered proportionally to the electric field applied thereto, such that an incident beam propagate through the crystal is modulated with an accumulated phase shift.

A structure including a substrate, an intermediate layer provided and formed directly onto the substrate, a transition region, and a group II-VI bulk crystal material provided and formed as an extension of the transition region. The transition region acts to change the structure from the underlying substrate to that of the bulk crystal. In a method of manufacture, a similar technique can be used for growing the transition region and the bulk crystal layer.

In one instance, the invention provides a method of growing bulk crystal of group III nitride using a seed crystal selected by (a) measuring x-ray rocking curves of a seed crystal at more than one point, (b) quantifying the peak widths of the measured x-ray rocking curves, and (c) evaluating the distribution of the quantified peak widths. The invention also includes the method of selecting a seed crystal for growing bulk crystal of group III nitride.

The bulk crystal of group III nitride can be grown in supercritical ammonia or a melt of group III metal using at least one seed selected by the method above.