Abstract: Provided is a semiconductor film having a corundum-type crystal structure composed of ?-Ga2O3 or an ?-Ga2O3 solid solution and the crystal defect density on at least one surface of the semiconductor film is 1.0×106/cm2 or less.

Abstract: Provided is an AlN single crystal substrate having a three-layer structure composed of one AlN single crystal as a whole and is classifiable into the first layer, the second layer, and the third layer in this order in the thickness direction in terms of defect density, wherein the second layer has a defect density of 10 times or more the defect density of each of the first layer and the third layer.

Abstract: A multilayer structure of the present invention is a multilayer structure including a base substrate and a semiconductor film that is made of ?-Ga2O3 or an ?-Ga2O3-based solid solution and has a corundum crystal structure, the semiconductor film being disposed on the base substrate. The semiconductor film has an average film thickness of greater than or equal to 10 ?m. The semiconductor film is convexly or concavely warped. An amount of warpage of the semiconductor film is 20 ?m or greater and 64 ?m or less.

Abstract: A rare earth-containing SiC substrate includes a rare earth element and Al. A concentration of the rare earth element is from 1×1016 atoms/cm3 to 1×1019 atoms/cm3 inclusive and a concentration of Al is from 1×1016 atoms/cm3 to 1×1021 atoms/cm3 inclusive.

Abstract: A biaxially oriented SiC composite substrate includes a first biaxially oriented SiC layer that contains a threading screw dislocation and a basal plane dislocation, and a second biaxially oriented SiC layer that is formed continuously from the first biaxially oriented SiC layer and that contains 1×1016 atoms/cm3 or more and 1×1019 atoms/cm3 or less of a rare earth element. The defect density of a surface of the second biaxially oriented SiC layer is smaller than the defect density of the first biaxially oriented SiC layer.

Abstract: Provided is an ?-Ga2O3 based semiconductor film having a crystal having a corundum-type crystal structure composed of ?-Ga2O3 or an ?-Ga2O3 solid solution as a main phase. This semiconductor film has a size in which the diameter of the largest circle inscribed in the outer circumference thereof is 5.08 cm (2 inches) or more, and at the center point X and each of four outer circumferential points A, B, C, and D of the largest circle on the surface of the semiconductor film, the full width at half maximum of the peak in the vicinity of 216 cm?1 in Raman spectrum of the semiconductor film, as measured by laser Raman spectroscopy, is 6.0 cm?1 or less.

Abstract: An ?-Ga2O3 semiconductor film according to the present invention has a measurement point (dark spot) with a maximum emission intensity A of not more than 0.6 times the average value X of top 5% of the maximum emission intensities A at all measurement points in intensity mapping of plane cathodoluminescence, wherein the maximum emission intensity A at each measurement point is determined in the wavelength range of 250 to 365 nm.

Abstract: Provided is a ?-Ga2O3 based semiconductor film which is a semiconductor film in a circular shape having a crystal having a corundum-type crystal structure composed of ?-Ga2O3 or an ?-Ga2O3 solid solution as a main phase. The maximum value ?max and the minimum value ?min for off-angles at the center point X and four outer circumferential points A, B, C, and D of a surface of the semiconductor film satisfy the relationship of ?max-?min?0.30°. The off-angle is defined as an inclination angle ? of a crystal axis oriented in the substantially normal direction of the semiconductor film with respect to the film surface normal of the semiconductor film.

Abstract: Provided is a semiconductor film having a corundum-type crystal structure composed of ?-Ga2O3 or an ?-Ga2O3 solid solution and the crystal defect density on at least one surface of the semiconductor film is 1.0×106/cm2 or less.

Abstract: Provided is a semiconductor film having a corundum-type crystal structure composed of ?-Ga2O3 or an ?-Ga2O3 solid solution, and an X-ray rocking curve full width at half maximum of a (104) plane on at least one surface of the semiconductor film is 500 arcsec or less.

Abstract: Provided is a semiconductor film having a corundum-type crystal structure composed of ?-Ga2O3 or an ?-Ga2O3 solid solution, and an impurity concentration and/or a heterogeneous phase amount differ between a front surface and a rear surface of the semiconductor film.

Abstract: Provided is a base substrate including an orientation layer used for crystal growth of a nitride or oxide of a Group 13 element. A front surface of the orientation layer on a side used for crystal growth is composed of a material having a corundum-type crystal structure having an a-axis length and/or c-axis length larger than that of sapphire. The orientation layer contains a solid solution containing two or more selected from the group consisting of ?-Al2O3, ?-Cr2O3, ?-Fe2O3, ?-Ti2O3, ?-V2O3, and ?-Rh2O3.

Abstract: Provided is a base substrate including an orientation layer used for crystal growth of a nitride or oxide of a Group 13 element, in which a front surface on a side used for the crystal growth of the orientation layer is composed of a material having a corundum-type crystal structure having an a-axis length and/or c-axis length larger than that of sapphire, the orientation layer contains a material selected from the group consisting of ?-Cr2O3, ?-Fe2O3, ?-Ti2O3, ?-V2O3, and ?-Rh2O3, or a solid solution containing two or more selected from the group consisting of ?-Al2O3, ?-Cr2O3, ?-Fe2O3, ?-Ti2O3, ?-V2O3, and ?-Rh2O3, and a half width of an X-ray rocking curve of a (104) plane of the corundum-type crystal structure is 500 arcsec. or less.

Abstract: Provided is a SiC composite substrate including a biaxially-oriented SiC layer in which SiC is oriented in both a c-axis direction and an a-axis direction, and a SiC polycrystalline layer provided on one surface of the biaxially-oriented SiC layer. Pores are present in the SiC composite substrate.

Abstract: Provided is a SiC composite substrate including a biaxially-oriented SiC layer in which SiC is oriented in both a c-axis direction and an a-axis direction, and a SiC polycrystalline layer provided on one surface of the biaxially-oriented SiC layer. A joint interface of the biaxially-oriented SiC layer and the SiC polycrystalline layer has an uneven shape, which has an amount of unevenness of 1 to 200 ?m.

Abstract: Provided is a ground substrate includes an orientation layer used for crystal growth of a nitride or oxide of a Group 13 element. The front surface of the orientation layer on the side used for the crystal growth is composed of a material having a corundum-type crystal structure having an a-axis length and/or c-axis length larger than that of sapphire. A plurality of pores are present in the orientation layer.

Abstract: A SiC composite substrate includes a SiC single crystal layer and at least one biaxially oriented SiC layer. The at least one biaxially oriented SiC layer is disposed on the SiC single crystal. In the biaxially oriented SiC layer, the SiC is oriented in both a c-axis direction and an a-axis direction. The biaxially oriented SiC layer has pores and has a density of defect reaching the surface of 1.0×101/cm2 or less.

Abstract: A method for producing an oriented sintered body according to the present invention includes the steps of: (a) preparing a multilayer body, the multilayer body including a layer including a fine raw-material powder and a layer including a plate-like raw-material powder which are alternately stacked each other, particles of the plate-like raw-material powder being arranged such that surfaces of the particles of the plate-like raw-material powder extend along a surface of the layer including a fine raw-material powder; and (b) sintering the multilayer body.

Abstract: A method for producing a transparent alumina sintered body according to the present invention includes (a) a step of preparing an alumina raw material powder containing a plate-like alumina powder having an aspect ratio of 3 or more and a fine alumina powder having an average particle diameter smaller than that of the plate-like alumina powder so that, when a mixing ratio of the plate-like alumina powder to the fine alumina powder in terms of mass ratio is assumed to be T:(100?T), T is 0.001 or more and less than 1, and so that a mass ratio R1 of F relative to Al in the alumina raw material powder is less than 15 ppm; (b) a step of forming a raw material for forming containing the alumina raw material powder into a compact; and (c) a step of sintering the compact so as to obtain a transparent alumina sintered body.

Abstract: An oriented ceramic sintered body production method includes (a) a step of preparing a ceramic compact before firing into an oriented ceramic sintered body; and (b) a step of obtaining an oriented ceramic sintered body by sandwiching the ceramic compact between a pair of releasing sheets, placing the ceramic compact and the releasing sheets in a hot press firing furnace, and hot press firing the ceramic compact while applying a pressure by a pair of punches through the pair of releasing sheets, wherein each of the releasing sheets is a releasing sheet such that, after the releasing sheet is sandwiched between PET films, is then placed and vacuum-packed on a stainless steel sheet, and is isostatically pressed at 200 kg/cm2, a surface of the releasing sheet on the side opposite from the stainless steel sheet has a profile curve with a maximum profile height Pt of 0.8 ?m or less.