Ngk Insulators, Inc.

Hiroshi Fukui

Morimichi Watanabe

Jun Yoshikawa

Tsutomu Nanataki

Kei Sato

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.

Underlying substrate

An α-GaOsemiconductor 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.

α-GaOsemiconductor film

Provided is an α-GaObased semiconductor film having a crystal having a corundum-type crystal structure composed of α-GaOor an α-GaOsolid 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 cmin Raman spectrum of the semiconductor film, as measured by laser Raman spectroscopy, is 6.0 cmor less.

Semiconductor film

Provided is a α-GaObased semiconductor film which is a semiconductor film in a circular shape having a crystal having a corundum-type crystal structure composed of α-GaOor an α-GaOsolid solution as a main phase. The maximum value θand the minimum value θfor 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 θ-θ≤0.30°. The off-angle is defined as an inclination angle θ 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.

Provided is a semiconductor film having a corundum-type crystal structure composed of α-GaOor an α-GaOsolid solution and the crystal defect density on at least one surface of the semiconductor film is 1.0×10/cmor less.

96 parts by mass of a &#x3b3;-alumina powder, 4 parts by mass of a an AlFpowder, and 0.17 parts by mass of an &#x3b1;-alumina powder as a seed crystal were mixed by a pot mill. The purities of each raw material were evaluated, and it was found that the mass ratio of each impurity element other than Al, O, F, H, C, and S was 10 ppm or less. In a high-purity alumina-made sagger having a purity of 99.9 percent by mass, 300 g of the obtained mixed powder was received, and after a high-purity alumina-made lid having a purity of 99.9 percent by mass was placed on the sagger, a heat treatment was perforated at 900&#xb0; C. for 3 hours in an electric furnace in an air flow atmosphere, so that an alumina powder was obtained. The value of AlFmass/container volume was 0.016 g/cm.

Method for manufacturing plate-like alumina powder and plate-like alumina powder

A plate-like alumina powder production method of the present invention comprises placing a transition alumina and a fluoride in a container such that the transition alumina and the fluoride do not come into contact with each other and then performing heat treatment to obtain a plate-like &#x3b1;-alumina powder. The transition alumina is preferably at least one selected from the group consisting of gibbsite, boehmite, and &#x3b3;-alumina. It is preferable that the amount of the fluoride used is set such that the percentage ration of F in the fluoride to the transition alumina is 0.17% by mass or more. The container preferably has a volume such that a value obtained by dividing the mass of F in the fluoride by the volume of the container is 6.5&#xd7;10g/cmor more. The heat treatment is preferably performed at the temperature of 750 to 1,650&#xb0; C.

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Obu, Japan

Hiroshi Fukui