Described herein is a method for growing indium nitride (InN) materials by growing hexagonal and/or cubic InN using a pulsed growth method at a temperature lower than 300° C. Also described is a material comprising InN in a face-centered cubic lattice crystalline structure having an NaCl type phase.

Single crystal CVD diamond material comprising a total nitrogen concentration of at least 5 ppm and a neutral single substitutional nitrogen. N.sub.s.sup.0, to total single substitutional nitrogen, N.sub.s, ratio of at least 0.7. Such a diamond is observed to have a relatively low amount of brown colouration despite the relatively high concentration of nitrogen A method of making the single crystal diamond is also disclosed, the method including growing the CVD diamond in process gases comprising 60 to 200 ppm nitrogen, in addition to a carbon-containing gas, and hydrogen, wherein the ratio of carbon atoms in the carbon-containing gas to hydrogen atoms in the hydrogen gas is 0.5 to 1.5%.

A method is disclosed for manufacturing lab grown diamond material by plasma enhanced chemical vapour deposition (PECVD). A substrate is exposed to a plasma containing carbon species while supported within a recess in a holder, resulting in a single crystal diamond (SCD) growing on the substrate while polycrystalline diamond (PCD) is deposited on the substrate holder. The relative rate of growth of the single crystal diamond on the substrate and the polycrystalline diamond on the surface of the holder is set, by control of at least one of the applied energy, cooling of the substrate holder and the chemical composition of the process gases, such that the single crystal diamond grown on the substrate protrudes above the surface of the holder and is constrained not to increase or to reduce in cross sectional area with increased distance from the surface of the holder by simultaneous growth of a polycrystalline diamond layer on the surface of the holder.

A method of manufacturing synthetic diamond material using a chemical vapour deposition process, and a diamond obtained by such a method are described. The method comprises providing a freestanding synthetic single crystal diamond substrate wafer having a dislocation density of at least 10.sup.7 cm.sup.−2. The synthetic single crystal diamond substrate wafer is located over a substrate holder within a chemical vapour deposition reactor. Process gases are fed into the reactor, the process gases including a gas comprising carbon. Crack-free synthetic diamond material is grown on a surface of the single crystal diamond substrate wafer at a temperature of at least 900° C. to a thickness of at least 0.5 mm and with lateral dimensions of at least 4 mm by 4 mm.

It is an object of the present invention to provide a silicon carbide substrate having a low defect density that does not contaminate a process device and a silicon carbide semiconductor device including the silicon carbide substrate. A silicon carbide substrate according to the present invention is a silicon carbide substrate including: a substrate inner portion; and a substrate outer portion surrounding the substrate inner portion, wherein non-dopant metal impurity concentration of the substrate inner portion is 1×10.sup.16 cm.sup.−3 or more, and a region of the substrate outer portion at least on a surface side thereof is a substrate surface region in which the non-dopant metal impurity concentration is less than 1×10.sup.16 cm.sup.−3.

The invention relates to a diamond-based gem. The diamond-based gem may include, at least one first portion comprising one of: a single crystal diamond and a transparent polycrystal diamond; and at least one second portion comprising opaque polycrystal diamond. Further are disclosed several methods for manufacturing such a diamond-based gem.

[Problem] To provide a crystal laminate structure having a β-Ga.sub.2O.sub.3 based single crystal film in which a dopant is included throughout the crystal and the concentration of the dopant can be set across a broad range. [Solution] In one embodiment of the present invention, provided is a crystal laminate structure 1 which includes: a Ga.sub.2O.sub.3 based substrate 10; and a β-Ga.sub.2O.sub.3 based single crystal film 12 formed by epitaxial crystal growth on a primary face 11 of the Ga.sub.2O.sub.3 based substrate 10 and including Cl and a dopant doped in parallel with the crystal growth at a concentration of 1×10.sup.13 to 5.0×10.sup.20 atoms/cm.sup.3.

A silicon carbide crystal and a manufacturing method thereof are provided. The silicon carbide crystal includes an N-type seed layer, a barrier layer, and a semi-insulating ingot, which are sequentially stacked and are made of silicon carbide. The N-type seed layer has a resistivity within a range of 0.01-0.03 Ω.Math.cm. The barrier layer includes a plurality of epitaxial layers sequentially formed on the N-type seed layer by an epitaxial process. The C/Si ratios of the epitaxial layers gradually increase in a growth direction away from the N-type seed layer. A nitrogen concentration of the silicon carbide crystal gradually decreases from the N-type seed layer toward the semi-insulating ingot by a diffusion phenomenon, so that the semi-insulating crystal has a resistivity larger than 10.sup.7 Ω.Math.cm.

A method of producing a synthetic diamond is disclosed. The method includes (a) capturing carbon dioxide from the atmosphere; (b) conducting electrolysis of water to provide hydrogen; (c) reacting the carbon dioxide obtained from step (a) with the hydrogen obtained from step (b) to produce methane; and (d) using the hydrogen obtained from step (b) and the methane obtained from step (c) to produce a synthetic diamond by chemical vapor deposition (CVD).

A method of producing a synthetic diamond is disclosed, the method comprising: (a) capturing carbon dioxide from the atmosphere; (b) conducting electrolysis of water to provide hydrogen; (c) reacting the carbon dioxide obtained from step (a) with the hydrogen obtained from step (b) to produce methane; and (d) using the hydrogen obtained from step (b) and the methane obtained from step (c) to produce a synthetic diamond by chemical vapour deposition (CVD).