There is described a single crystal CVD diamond material comprising three orthogonal dimensions of at least 2 mm; one or more regions of low optical birefringence, indicative of low strain, such that in a sample of the single crystal CVD diamond material having a thickness in a range 0.5 mm to 1.0 mm and an area of greater than 1.3 mm×1.3 mm and measured using a pixel size of area in a range 1×1 μm.sup.2 to 20×20 μm.sup.2, a maximum value of Δn.sub.[average] does not exceed 1.5×10.sup.−4 for the one or more regions of low optical birefringence, where Δn.sub.[average] is an average value of a difference between refractive index for light polarised parallel to slow and fast axes averaged over the sample thickness; one or more regions of high optical birefringence, indicative of high strain, such that in said sample of the single crystal CVD diamond material and measured using said pixel size, Δn.sub.[average] is greater than 1.5×10.sup.−4 and less than 3×10.sup.−3; and is wherein every 1.3 mm×1.3 mm area of the sample of the single crystal CVD diamond material comprises at least one of said regions of high optical birefringence. There is also described a method of making the CVD diamond material.

A diamond die includes a diamond provided with a hole for drawing a wire material, the diamond being a CVD single-crystal diamond, an axis of the hole being inclined relative to a normal direction of a crystal plane of the diamond.

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

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.

A diamond crystal substrate has a substrate surface that is one crystal plane among (100), (111), and (110) and that has atomic steps and terraces structure at an off-angle of 7 or less excluding 0.

There is provided a novel stack that includes a single-crystal diamond substrate having a coalescence boundary, yet effectively uses the coalescence boundary. A stack comprising at least a semiconductor drift layer stacked on a single-crystal diamond substrate having a coalescence boundary, wherein the coalescence boundary of the single-crystal diamond substrate is a region that exhibits, in a Raman spectrum at a laser excitation wavelength of 785 nm, a full width at half maximum of a peak near 1332 cm.sup.1 due to diamond that is observed to be broader than a full width at half maximum of the peak exhibited by a region different from the coalescence boundary, the coalescence boundary has a width of 200 m or more, and the semiconductor drift layer is stacked on at least the coalescence boundary.

The disclosure relates to large area single crystal diamond (SCD) surfaces and substrates, and their methods of formation. Typical large area substrates can be at least about 25 mm, 50 mm, or 100 mm in diameter or square edge length, and suitable thicknesses can be about 100 m to 1000 m. The large area substrates have a high degree of crystallographic alignment. The large area substrates can be used in a variety of electronics and/or optics applications. Methods of forming the large area substrates generally include lateral and vertical growth of SCD on spaced apart and crystallographically aligned SCD seed substrates, with the individual SCD growth layers eventually merging to form a composite SCD layer of high quality and high crystallographic alignment. A diamond substrate holder can be used to crystallographically align the SCD seed substrates and reduce the effect of thermal stress on the formed SCD layers.

There is described a single crystal CVD diamond material comprising three orthogonal dimensions of at least 2 mm; one or more regions of low optical birefringence, indicative of low strain, such that in a sample of the single crystal CVD diamond material having a thickness in a range 0.5 mm to 1.0 mm and an area of greater than 1.3 mm1.3 mm and measured using a pixel size of area in a range 11 m.sup.2 to 2020 m.sup.2, a maximum value of n.sub.[average] does not exceed 1.510.sup.4 for the one or more regions of low optical birefringence, where n.sub.[average] is an average value of a difference between refractive index for light polarised parallel to slow and fast axes averaged over the sample thickness; one or more regions of high optical birefringence, indicative of high strain, such that in said sample of the single crystal CVD diamond material and measured using said pixel size, n.sub.[average] is greater than 1.510.sup.4 and less than 310.sup.3; and is wherein every 1.3 mm1.3 mm area of the sample of the single crystal CVD diamond material comprises at least one of said regions of high optical birefringence. There is also described a method of making the CVD diamond material.

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 single crystal CVD diamond component comprising: a surface, wherein at least a portion of said surface is formed of as-grown growth face single crystal CVD diamond material which has not been polished or etched and which has a surface roughness R.sub.a of no more than 100 nm; and a layer of NV.sup. defects, said layer of NV.sup. defects being disposed within 1 m of the surface, said layer of NV.sup. defects having a thickness of no more than 500 nm, and said layer of NV.sup. defects having a concentration of NV.sup. defects of at least 10.sup.5 NV.sup./cm.sup.2.