Group-III element nitride semiconductor substrate including a first surface and a second surface that are easy to visually distinguish from each other. An end portion is easily detected with an optical sensor, a large effective area (area that can be used in device production) can be secured, and warping of the entirety of the substrate is reduced. A Group-III element nitride semiconductor substrate includes a first surface; and a second surface, wherein the first surface is a mirror surface, the second surface has a second-surface central region and a second-surface outer peripheral region, the second-surface central region is a mirror surface, and the second-surface outer peripheral region is a non-mirror surface.

To produce hexagonal boron nitride (h-BN), boron and nitrogen are added to a metallic solvent in a crucible in a reaction chamber and heat-treated. In an absorption step, a first soak is performed at a first temperature that is high enough to cause absorption of the nitrogen and boron into the metallic solvent. In a nucleation step after the absorption step, the first temperature is rapidly reduced to a second temperature, and h-BN nuclei are formed in the metallic solvent. In a growth step after the nucleation step, a second soak is performed at the second temperature to grow the h-BN nuclei. After the growth step, the h-BN nuclei are separated from the metallic solvent.

To produce hexagonal boron nitride (h-BN), boron and nitrogen are added to a metallic solvent in a crucible in a reaction chamber and heat-treated. In an absorption step, a first soak is performed at a first temperature that is high enough to cause absorption of the nitrogen and boron into the metallic solvent. In a nucleation step after the absorption step, the first temperature is rapidly reduced to a second temperature, and h-BN nuclei are formed in the metallic solvent. In a growth step after the nucleation step, a second soak is performed at the second temperature to grow the h-BN nuclei. After the growth step, the h-BN nuclei are separated from the metallic solvent.

Provided is a synthetic single crystal diamond containing conjugants each composed of one vacancy and one boron atom, wherein the concentration of boron atoms based on atom numbers is 0.1 ppm or more and 100 ppm or less.

Provided is a synthetic single crystal diamond containing conjugants each composed of one vacancy and one boron atom, wherein the concentration of boron atoms based on atom numbers is 0.1 ppm or more and 100 ppm or less.

The disclosure relates to a method for making an iron telluride including placing Fe, Bi, and Te in a reacting chamber as reacting materials. The reacting chamber is evacuated to be a vacuum with a pressure lower than 10 Pa. The reacting chamber is heated to a first temperature of 700 degrees Celsius to 900 degrees Celsius and keeping the first temperature for a period of 10 hours to 14 hours. Then the reacting chamber is cooled to a second temperature of 400 degrees Celsius to 700 degrees Celsius within 60 hours to 75 hours and keeping the second temperature for a period of 40 hours to 50 hours, to obtain a reaction product including a FeTe.sub.0.9 single crystal. The FeTe.sub.0.9 single crystal is separated from the reaction product.

A layer of a crystal of a nitride of a group 13 element selected from gallium nitride, aluminum nitride, indium nitride and the mixed crystals thereof includes an upper surface and a bottom surface. The upper surface includes a linear high-luminance light-emitting part and a low-luminance light-emitting region adjacent to the high-luminance light-emitting part, and the high-luminance light-emitting part has a portion extending along an m-plane of the crystal of the nitride of the group 13 element, when the upper surface is observed by cathode luminescence. The upper surface has an arithmetic average roughness Ra of 0.05 nm or more and 1.0 nm or less.

Alumina is generally used as an inorganic filler, while spinel, which is known to be lower in thermal conductivity than alumina, is used in applications such as gems, fluorescence emitters, catalyst carriers, adsorbents, photocatalysts and heat-resistant insulating materials, but not expected to be used as a thermally conductive inorganic filler. Thus, an object of the invention is to provide spinel particles having excellent thermal conductive properties. The invention relates to a spinel particle including magnesium, aluminum and oxygen atoms and molybdenum and having a [111] plane crystallite diameter of 220 nm or more.

It is provided a layer of a nitride of a group 13 element having a first main face and second main face. The layer of the nitride of the group 13 element includes a first void-depleted layer provided on the side of the first main face, a second void-depleted layer provided on the side of the second main face, and the void-distributed layer provided between the first void-depleted layer and second void-depleted layer.

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.