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 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.

Technologies relating to a magnetic resonance spectrometer are disclosed. The magnetic resonance spectrometer may include a doped nanostructured crystal. By nanostructuring the surface of the crystal, the sensor-sample contact area of the crystal can be increased. As a result of the increased sensor-sample contact area, the output fluorescence signal emitted from the crystal is also increased, with corresponding reductions in measurement acquisition time and requisite sample volumes.

Technologies relating to a magnetic resonance spectrometer are disclosed. The magnetic resonance spectrometer may include a doped nanostructured crystal. By nanostructuring the surface of the crystal, the sensor-sample contact area of the crystal can be increased. As a result of the increased sensor-sample contact area, the output fluorescence signal emitted from the crystal is also increased, with corresponding reductions in measurement acquisition time and requisite sample volumes.

An underlying substrate including a seed crystal layer of a group 13 nitride, wherein projections and recesses repeatedly appear in stripe shapes at a principal surface of the seed crystal layer, and the projections have a level difference of 0.3 to 40 m and a width of 5 to 100 m, and the recesses have a bottom thickness of 2 m or more and a width of 50 to 500 m.

An underlying substrate including a seed crystal layer of a group 13 nitride, wherein projections and recesses repeatedly appear in stripe shapes at a principal surface of the seed crystal layer, and the projections have a level difference of 0.3 to 40 m and a width of 5 to 100 m, and the recesses have a bottom thickness of 2 m or more and a width of 50 to 500 m.

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.

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.

A trench MOS Schottky diode includes a first semiconductor layer including a Ga.sub.2O.sub.3-based single crystal, a second semiconductor layer that is a layer stacked on the first semiconductor layer, includes a Ga.sub.2O.sub.3-based single crystal, and includes a trench opened on a surface thereof opposite to the first semiconductor layer, an anode electrode formed on the surface of the second semiconductor layer, a cathode electrode formed on a surface of the first semiconductor layer, an insulating film covering the inner surface of the trench of the second semiconductor layer, and a trench electrode that is buried in the trench of the second semiconductor layer so as to be covered with the insulating film and is in contact with the anode electrode. The second semiconductor layer includes an insulating dry-etching-damaged layer with a thickness of not more than 0.8 m in a region including the inner surface of the trench.

A method of producing a functional device has an etched gallium nitride layer and a functional layer having a nitride of a group 13 element. The method includes providing a body comprising a surface gallium nitride layer, performing a dry etching treatment of a surface of the surface gallium nitride layer to provide the etched gallium nitride layer using a plasma etching system comprising an inductively coupled plasma generating system, introducing an etchant during the dry etching treatment, the etchant consisting essentially of a fluorine-based gas, and forming the functional layer on a surface of the etched gallium nitride layer.