Abstract: There is provided a large-diameter Group-III element nitride semiconductor substrate including a first surface and a second surface, in which, despite its large diameter, variations in quality in the first surface are suppressed. A Group-III element nitride semiconductor includes: a first surface; and a second surface, wherein the Group-III element nitride semiconductor substrate has a diameter of 100 mm or more, and wherein the Group-III element nitride semiconductor substrate has a coefficient of variation of a yellow luminescence intensity in a range corresponding to 88% or more of an entire region of the first surface of 0.3 or less based on a photoluminescence spectrum obtained through photoluminescence measurement of a range of the entire region of the first surface.

Abstract: It is provided a seed crystal layer, composed of a group 13 nitride crystal selected from gallium nitride, aluminum nitride, indium nitride or the mixed crystals thereof, on an alumina layer on a single crystal substrate. By annealing under reducing atmosphere at a temperature of 950° C. or higher and 1200° C. or lower, convex-concave morphology is formed on a surface of the seed crystal layer so as to have an RMS value of 180 nm to 700 nm measured by an atomic force microscope. On the surface of the seed crystal layer, it is grown a group 13 nitride crystal layer composed of a group 13 nitride crystal selected from gallium nitride, aluminum nitride, indium nitride or the mixed crystals thereof.

Abstract: A layer of a crystal of a group 13 nitride selected from gallium nitride, aluminum nitride, indium nitride and the mixed crystals thereof has an upper surface and a bottom surface. The upper surface of a crystal layer of the group 13 nitride includes a linear high-luminance light-emitting part and a low-luminance light-emitting region adjacent to the high-luminance light-emitting part, observed by cathode luminescence. The high-luminance light-emitting part includes a portion extending along an m-plane of the crystal of the group 13 nitride. The crystal of the nitride of the group 13 element contains oxygen atoms in a content of 1×1018 atom/cm3 or less, silicon atoms, manganese atoms, carbon atoms, magnesium atoms and calcium atoms in contents of 1×1017 atom/cm3 or less, chromium atoms in a content of 1×1016 atom/cm3 or less and chlorine atoms in a content of 1×1015 atom/cm3 or less.

Abstract: A layer of a crystal of a group 13 nitride selected from gallium nitride, aluminum nitride, indium nitride and the mixed crystals thereof has 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. The high-luminance light-emitting part includes a portion extending along an m-plane of the crystal of the group 13 nitride. A normal line to the upper surface has an off-angle of 2.0° or less with respect to <0001> direction of the crystal of the nitride of the group 13 element.

Abstract: A group 13 nitride crystal layer is composed of a group 13 nitride crystal selected from gallium nitride, aluminum nitride, indium nitride or the mixed crystals thereof, and the group 13 nitride crystal layer includes an upper surface and bottom surface. The group 13 nitride crystal layer includes high-luminance layers and low-luminance layers being present alternately, and the low-luminance layers have thicknesses of 3 or larger and 10 or smaller provided that 1 is assigned to a thickness of the high-luminance layer, when a cross section of the group 13 nitride crystal layer cut in a direction perpendicular to the upper surface is observed by cathode luminescence.

Abstract: It is provided a seed crystal layer, composed of a group 13 nitride crystal selected from gallium nitride, aluminum nitride, indium nitride or the mixed crystals thereof, on an alumina layer on a single crystal substrate. By annealing under reducing atmosphere at a temperature of 950° C. or higher and 1200° C. or lower, convex-concave morphology is formed on a surface of the seed crystal layer so as to have an RMS value of 180 nm to 700 nm measured by an atomic force microscope. On the surface of the seed crystal layer, it is grown a group 13 nitride crystal layer composed of a group 13 nitride crystal selected from gallium nitride, aluminum nitride, indium nitride or the mixed crystals thereof.

Abstract: 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.

Abstract: [Problems] To easily and efficiently manufacture a catalyst layer having high catalytic activity and to easily manufacture a fuel cell having high power generation efficiency. [Solution] An apparatus for forming a catalyst layer 3 for a fuel cell on an electrolyte film (application object) 2, the apparatus including: a holding portion 6 that holds a sheet-shaped electrolyte film 2, an application portion 7 that applies a catalyst ink 5 for forming the catalyst layer 3 on at least one side of the electrolyte film 2 held by the holding portion 6, a chamber portion 8 that is capable of forming a space 55 including the holding portion 6, and a suction portion 9 that depressurizes the inside of the space 55 formed by the chamber portion 8 so as to dry the catalyst ink 5.

Abstract: A crystal of a group 13 nitride has an upper surface and lower surface and is composed of a crystal of a group 13 nitride selected from gallium nitride, aluminum nitride, indium nitride or the mixed crystals thereof. When the upper surface of the layer of the crystal of the group 13 nitride is observed by cathode luminescence, 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. A half value width of reflection at the (0002) plane of a X-ray rocking curve on the upper surface is 3000 seconds or less and 20 seconds or more.

Abstract: 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.

Abstract: A layer of a crystal of a group 13 nitride selected from gallium nitride, aluminum nitride, indium nitride and the mixed crystals thereof has an upper surface and a bottom surface. The upper surface of the crystal layer of the group 13 nitride includes a linear high-luminance light-emitting part and a low-luminance light-emitting region adjacent to the high-luminance light-emitting part, observed by cathode luminescence. The high-luminance light-emitting part includes a portion extending along an m-plane of the crystal of the group 13 nitride.

Abstract: 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.

Abstract: A free-standing substrate of a polycrystalline nitride of a group 13 element contains a plurality of monocrystalline particles having a particular crystal orientation in approximately a normal direction. The polycrystalline nitride of the group 13 element is composed of gallium nitride, aluminum nitride, indium nitride or a mixed crystal thereof. The free-standing substrate has a top surface and bottom surface. The free-standing substrate contains at least one of zinc and calcium. A root mean square roughness Rms at the top surface is 3.0 nm or less.

Abstract: A membrane catalyst layer assembly production method is provided for producing a membrane catalyst layer assembly by discharging catalyst ink having a solvent and a solid component onto an electrolyte membrane. The membrane catalyst layer assembly production method includes forming a first catalyst ink layer having a first porosity on the electrolyte membrane by controlling a porosity of a catalyst ink layer that is formed by the catalyst ink making impact with the electrolyte membrane by adjusting an amount of solvent in the catalyst ink in drop form prior to impact with the electrolyte membrane, and forming a second catalyst ink layer having a second porosity, which is different from the first porosity, on the first catalyst ink layer, by adjusting the amount of solvent in the catalyst ink in drop form prior to impact with the first catalyst ink layer.

Abstract: A free-standing substrate of a polycrystalline nitride of a group 13 element is composed of a plurality of monocrystalline particles having a particular crystal orientation in approximately a normal direction. The free-standing substrate has a top surface and a bottom surface. The polycrystalline nitride of the group 13 element is gallium nitride, aluminum nitride, indium nitride or a mixed crystal thereof and contains zinc at a concentration of 1×1017 atoms/cm3 or more and 1×1020 atoms/cm3 or less.

Abstract: A layer of a crystal of a group 13 nitride selected from gallium nitride, aluminum nitride, indium nitride and the mixed crystals thereof has an upper surface and a bottom surface. The upper surface of a crystal layer of the group 13 nitride includes a linear high-luminance light-emitting part and a low-luminance light-emitting region adjacent to the high-luminance light-emitting part, observed by cathode luminescence. The high-luminance light-emitting part includes a portion extending along an m-plane of the crystal of the group 13 nitride. A normal line to the upper surface has an off-angle of 2.0° or less with respect to <0001> direction of the crystal of the nitride of the group 13 element.

Abstract: It is provided 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, and the layer 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, in the case that 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.

Abstract: It is provided a layer of a crystal of a group 13 nitride having an upper surface and lower surface and composed of a crystal of the group 13 nitride selected from gallium nitride, aluminum nitride, indium nitride or the mixed crystals thereof. In the case that the upper surface of the layer of the crystal of the group 13 nitride is observed by cathode luminescence, 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. A half value width of reflection at (0002) plane of an X-ray rocking curve on the upper surface is 3000 seconds or less and 20 seconds or more.

Abstract: A layer of a crystal of a group 13 nitride selected from gallium nitride, aluminum nitride, indium nitride and the mixed crystals thereof has an upper surface and a bottom surface. The upper surface of a crystal layer of the group 13 nitride includes a linear high-luminance light-emitting part and a low-luminance light-emitting region adjacent to the high-luminance light-emitting part, observed by cathode luminescence. The high-luminance light-emitting part includes a portion extending along an m-plane of the crystal of the group 13 nitride.

Abstract: A layer of a crystal of a group 13 nitride selected from gallium nitride, aluminum nitride, indium nitride and the mixed crystals thereof has an upper surface and a bottom surface. The upper surface of a crystal layer of the group 13 nitride includes a linear high-luminance light-emitting part and a low-luminance light-emitting region adjacent to the high-luminance light-emitting part, observed by cathode luminescence. The high-luminance light-emitting part includes a portion extending along an m-plane of the crystal of the group 13 nitride. The crystal of the nitride of the group 13 element contains oxygen atoms in a content of 1×1018 atom/cm3 or less, silicon atoms, manganese atoms, carbon atoms, magnesium atoms and calcium atoms in contents of 1×1017 atom/cm3 or less, chromium atoms in a content of 1×1016 atom/cm3 or less and chlorine atoms in a content of 1×1015 atom/cm3 or less.