To provide polycrystalline silicon suitable as a raw material for production of single-crystalline silicon. A D/L value is set within the range of less than 0.40 when multiple pairs of silicon cores are placed in a reaction furnace in production of a polycrystalline silicon rod having a diameter of 150 mm or more by deposition according to a chemical vapor deposition process and it is assumed that the average value of the final diameter of the polycrystalline silicon rod is defined as D (mm) and the mutual interval between the multiple pairs of silicon cores is defined as L (mm).

The disclosed materials, methods, and apparatus, provide novel ultra-high temperature materials (UHTM) in fibrous forms/structures; such “fibrous materials” can take various forms, such as individual filaments, short-shaped fiber, tows, ropes, wools, textiles, lattices, nano/microstructures, mesostructured materials, and sponge-like materials. At least four important classes of UHTM materials are disclosed in this invention: (1) carbon, doped-carbon and carbon alloy materials, (2) materials within the boron-carbon-nitride-X system, (3) materials within the silicon-carbon-nitride-X system, and (4) highly-refractory materials within the tantalum-hafnium-carbon-nitride-X and tantalum-hafnium-carbon-boron-nitride-X system. All of these material classes offer compounds/mixtures that melt or sublime at temperatures above 1800° C.—and in some cases are among the highest melting point materials known (exceeding 3000° C.). In many embodiments, the synthesis/fabrication is from gaseous, solid, semi-solid, liquid, critical, and supercritical precursor mixtures using one or more low molar mass precursor(s), in combination with one or more high molar mass precursor(s). Methods for controlling the growth, composition, and structures of UHTM materials through control of the thermal diffusion region are disclosed.

A composite substrate includes a sapphire substrate and a layer of a nitride of a group 13 element provided on the sapphire substrate. The layer of the nitride of the group 13 element is composed of gallium nitride, aluminum nitride or gallium aluminum nitride. The composite substrate satisfies the following formulas (1), (2) and (3). A laser light is irradiated to the composite substrate from the side of the sapphire substrate to decompose crystal lattice structure at an interface between the sapphire substrate and the layer of the nitride of the group 13 element. 5.0≦(an average thickness (μm) of the layer of the nitride of the group 13 element/a diameter (mm) of the sapphire substrate)≦10.0 . . . (1); 0.1≦ a warpage (mm) of said composite substrate×(50/a diameter (mm) of said composite substrate).sup.20.6 . . . (2); 1.10≦a maximum value (μm) of a thickness of said layer of said nitride of said group 13 element/a minimum value (μm) of said thickness of said layer of said nitride of said group 13 element . . . (3)

A method for making a monocrystalline structure is disclosed. The method includes depositing a first volume of a material on a substrate to create a first crystal seed and depositing a second volume of the material towards the substrate to nucleate with the first crystal seed to create a first initial epitaxial structure.

A chemical vapor deposition method comprises flowing a carrier liquid through a reactor. A fluid comprising one or more reactants is introduced into the carrier liquid. The fluid is at a first temperature and first pressure and is sufficiently immiscible in the carrier liquid so as to form a plurality of microreactors suspended in the carrier liquid. Each of the microreactors comprise a discrete volume of the fluid and have a surface boundary defined by an interface of the fluid with the carrier liquid. The fluid is heated and optionally pressurized to a second temperature and second pressure at which a chemical vapor deposition reaction occurs within the microreactors to form a plurality of chemical vapor deposition products. The plurality of chemical vapor deposition products are separated from the carrier liquid. A system for carrying out the method of the present disclosure is also taught.

A method includes placing a first charged metal dot on a first position of a surface of a semiconductor substrate. A first charged region is formed on a second position of the surface of the semiconductor substrate. A precursor gas is flowed along a first direction from the first position toward the second position on the semiconductor substrate, thereby forming a first carbon nanotube (CNT) on the semiconductor substrate. A dielectric layer is deposited to cover the first CNT and the semiconductor substrate. A second charged metal dot is placed on a third position of a surface of the dielectric layer. A second charged region is formed on a fourth position of the surface of the dielectric layer. The precursor gas is flowed along a second direction from the third position toward the fourth position on the semiconductor substrate, thereby forming a second CNT on the first CNT.

A method of depositing silicon carbide on a preform to form a ceramic matrix composite comprises placing the preform into a reaction vessel, removing air from the reaction vessel and backfilling the reaction vessel with an inert gas to an operating pressure. The reaction vessel and the preform are heated to an operating temperature. A carrier gas and precursor materials are heated to a preheat temperature outside of the reaction vessel. The carrier gas and the precursor materials are introduced to the reaction vessel in a specified ratio. Off gasses, the precursor materials that are unspent, and the carrier gas are removed from the reaction vessel to maintain the specified ratio of the precursor materials in the reaction vessel.

A composite tape and method of fabrication are provided which includes multiple layers and a laser-driven chemical vapor deposition (LCVD)-formed additive material in at least one layer of the multiple layers to enhance one or more properties of the composite tape. The LCVD-formed additive material is a single crystalline material and can include LCVD-formed granular material and/or LCVD-formed fiber material in the same or different layers of the composite tape to enhance, for instance, fracture strength and/or wear resistance of the composite tape.

The invention discloses equipment and preparation method for open and continuous growth of a carbon nanomaterial. The equipment comprises a metal foil tape feeding system, a CVD system and a collection system. The method includes continuously conveying a metal foil tape pretreated or not into the CVD system via the metal foil tape feeding system, depositing a required carbon nanomaterial on the surface of the metal foil tape by CVD, directly collecting by the collection system or directly post-treating the carbon nanomaterial by a post-treatment system, and even directly producing a end product of the carbon nanomaterial. All the systems in the invention are arranged in the open atmosphere rather than an air-isolated closed space. The invention can realize round-the-clock continuous operation to greatly improve the production efficiency of carbon nanomaterials.

A method for making a carbon fiber film includes suspending a carbon nanotube film in a chamber. A negative voltage is applied to the carbon nanotube film. A carbon source gas is supplied into the chamber, wherein the carbon source gas is cracked to form carbon free radicals, and the carbon free radicals are graphitized to form a graphite layer on the carbon nanotube film.