A CVD single crystal diamond material suitable for use in, or as, an optical device or element. It is suitable for use in a wide range of optical applications such as, for example, optical windows, laser windows, optical reflectors, optical refractors and gratings, and etalons. The CVD diamond material is produced by a CVD method in the presence of a controlled low level of nitrogen to control the development of crystal defects and thus achieve a diamond material having key characteristics for optical applications.

The present technology relates to diamond materials and structures created using chemical vapor deposition techniques (i.e., creation of synthetic diamond). The chemical vapor deposited diamond includes a multiphase material comprising (a) a single crystalline matrix phase and (b) plurality of diamond grains, each of the plurality of diamond grains being crystallographically distinct from the single crystalline matrix phase.

A SiC epitaxial wafer includes a SiC substrate and an epitaxial layer laminated on the SiC substrate, wherein the epitaxial layer contains an impurity element which determines the conductivity type of the epitaxial layer and boron which has a conductivity type different from the conductivity type of the impurity element, and the concentration of boron is less than 1.010.sup.14 cm.sup.3 at any position in the plane of the epitaxial layer.

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.

Provided is a method for manufacturing a single-crystal diamond, the method including the steps of: forming a protective film on at least a part of a surface of an auxiliary plate; preparing a diamond seed crystal substrate; disposing an auxiliary plate with a protective film that has the protective film formed on the auxiliary plate, and a diamond seed crystal substrate in a chamber; and growing a single-crystal diamond on a principal surface of the diamond seed crystal substrate by a chemical vapor deposition method while introducing a carbon-containing gas into the chamber.

A microwave plasma reactor for manufacturing synthetic diamond material via chemical vapour deposition, the microwave plasma reactor comprising: a plasma chamber defining a resonant cavity for supporting a primary microwave resonance mode having a primary microwave resonance mode frequency f; a plurality of microwave sources coupled to the plasma chamber for generating and feeding microwaves having a total microwave power P into the plasma chamber; a gas flow system for feeding process gases into the plasma chamber and removing them therefrom; and a substrate holder disposed in the plasma chamber and comprising a supporting surface for supporting a substrate on which the synthetic diamond material is to be deposited in use, wherein the plurality of microwave sources are configured to couple at least 30% of the total microwave power P into the plasma chamber in the primary microwave resonance mode frequency f, and wherein at least some of the plurality of microwave sources are solid state microwave sources.

A semiconductor substrate that is used as an underlying substrate for epitaxial crystal growth carried out by the HVPE method includes a -Ga.sub.2O.sub.3-based single crystal, and a principal plane that is a plane parallel to a [100] axis of the -Ga.sub.2O.sub.3-based single crystal. An epitaxial wafer includes the semiconductor substrate, and an epitaxial layer including a -Ga.sub.2O.sub.3-based single crystal and formed on the principal plane of the semiconductor substrate by epitaxial crystal growth using the HVPE method. A method for producing an epitaxial wafer includes by using the HVPE method, epitaxially growing an epitaxial layer including a -Ga.sub.2O.sub.3-based single crystal on a semiconductor substrate that includes a -Ga.sub.2O.sub.3-based single crystal and has a principal plane parallel to a [100] axis of the -Ga.sub.2O.sub.3-based single crystal.

A single-crystal diamond material has a transmittance of light with a wavelength of greater than or equal to 410 nm and less than or equal to 750 nm of less than or equal to 15% for any wavelength, and is at least either of an electrical insulator according to optical evaluation and an electrical insulator according to electrical evaluation. A criterion of the optical evaluation can be a transmittance of light with a wavelength of 10.6 m of greater than or equal to 1%. A criterion of the electrical evaluation can be an average resistivity of greater than or equal to 110.sup.6 cm. Accordingly, a single-crystal diamond material having a low transmittance of light in the entire region of the visible light region and exhibiting a black color is provided.

A method of producing a large single crystal diamond comprising of: (i) arranging two or more single crystal diamond substrates adjacent to one another in a diamond growth chamber, wherein each single crystal diamond substrate include at least 2 adjacent surfaces having different crystallographic orientations, (ii) using a diamond growth process, growing the single crystal diamond substrates in an upward growth direction as well as in a lateral growth direction.

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 .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 .Math.cm.