Abstract: There is provided a nitride crystal substrate constituted by group-III nitride crystal, containing n-type impurities, with an absorption coefficient ? being approximately expressed by equation (1) by a least squares method in a wavelength range of at least 1 ?m or more and 3.3 ?m or less. ? = N e ? K ? ? a ? ( where 1.5 × 10 - 19 ? K ? 6. × 10 - 19 , a = 3 ) , ( 1 ) here, a wavelength is ? (?m), an absorption coefficient of the nitride crystal substrate at 27° C. is ? (cm?1), a carrier concentration in the nitride crystal substrate is Ne (cm?3), and K and a are constants, wherein an error of an actually measured absorption coefficient with respect to the absorption coefficient ? obtained from equation (1) at a wavelength of 2 ?m is within +0.1?, and in a reflection spectrum measured by irradiating the nitride crystal substrate with infrared light, there is no peak with a peak top within a wavenumber range of 1,200 cm?1 or more and 1,500 cm?1 or less.

Abstract: A method for manufacturing a structure, including photoelectrochemically etching an etching object, the photoelectrochemical etching of the etching object including: injecting an alkaline or acidic etching solution containing an oxidizing agent that receives electrons, into a rotatably held container in which an etching object at least whose surface is composed of group III nitride is held, and immersing the surface in the etching solution; irradiating the surface of the etching object held in the container with light in a stationary state of the etching object and the etching solution; and rotating the container to scatter the etching solution toward an outer peripheral side, thereby discharging the etching solution from the container, after the surface is irradiated with the light.

Abstract: There is provided a method for manufacturing a nitride-based high electron mobility transistor, including: providing a conductive member on a nitride semiconductor crystal substrate, outside an element region in a plan view; forming a mask on the substrate, the mask having an opening in at least one of a source recess etching region and a drain recess etching region; performing photoelectrochemical etching by irradiating the substrate with light to form at least one of a source recess and a drain recess, in a state where the substrate on which the conductive member is provided and the mask is formed is in contact with an etching solution containing an oxidizing agent that receives electrons; and forming an element separation structure of the high electron mobility transistor.

Abstract: A nitride semiconductor substrate including a group III nitride semiconductor crystal and having a main surface, wherein a low index crystal plane is (0001) plane curved in a concave spherical shape to the main surface, and the off-angle (?m, ?a) at a position (x, y) in the main surface approximated by x representing a coordinate in a direction along <1-100> axis, y is a coordinate in a direction along <11-20> axis, (0, 0) represents a coordinate (x, y) of the center, ?m represents a direction component along <1-100> axis in an off-angle of <0001> axis with respect to a normal, ?a represents a direction component along <11-20> axis in the off-angle, (M1, A1) represents a rate of change in the off-angle (?m, ?a) with respect to the position (x, y) in the main surface, and (M2, A2) represents the off-angle (?m, ?a) at the center.

Abstract: There is provided a method for producing a nitride semiconductor laminate in which a thin film is homoepitaxially grown on a substrate comprising group III nitride semiconductor crystals, the method including: homoepitaxially growing a thin film on a substrate, using the substrate in which a dislocation density on its main surface is 5×106 pieces/cm2 or less, a concentration of oxygen therein is less than 1×1017 at·cm?3, and a concentration of impurities therein other than n-type impurity is less than 1×1017 at ·cm?3; and inspecting a film quality of the thin film formed on the substrate, wherein in the inspection of the film quality, the film quality of the thin film is inspected by detecting a deviation of an amount of reflected light at a predetermined wavenumber determined in a range of 1,600 cm?1 or more and 1,700 cm?1 or less in a reflection spectrum obtained by irradiating the thin film on the substrate with infrared light, from an amount of reflected light at the predetermined wavenumber determined ac

Abstract: There is provided a laminated substrate having a piezoelectric film, including: a substrate; a first electrode film provided on the substrate; and a piezoelectric film provided on the first electrode film, wherein an oxide film containing an oxide represented by a composition formula of RuOx or IrOx, is provided on the piezoelectric film.

Abstract: There is provided a structure manufacturing method, including: preparing an etching target at least whose top surface comprises group III nitride crystal, and an alkaline or acidic etching liquid containing peroxodisulfate ion as an oxidizing agent that receives electrons; irradiating the top surface of the etching target with light while rotating the etching target, with the top surface of the etching target immersed in the etching liquid heated to generate sulfate ion radicals.

Abstract: There is provided a structure manufacturing method, including: preparing a wafer at least whose surface comprises Group III nitride crystal in a state of being immersed in an etching solution containing peroxodisulfate ions; and irradiating the surface of the wafer with light through the etching solution; wherein the group III nitride crystal has a composition in which a wavelength corresponding to a band gap is 310 nm or more, and during irradiation of the light, the surface of the wafer is irradiated with a first light having a wavelength of 200 nm or more and less than 310 nm under a first irradiation condition, and is irradiated with a second light having a wavelength of 310 nm or more and less than a wavelength corresponding to the band gap under a second irradiation condition controlled independently of the first irradiation condition.

Abstract: There is provided a piezoelectric laminate, including: a substrate; and a piezoelectric film formed on the substrate, wherein the piezoelectric film contains an alkali niobium oxide represented by a composition formula of (K1?xNax)NbO3 (0<x<1), having a perovskite structure, and contains a metallic element selected from a group consisting of Cu and Mn at a concentration of more than 0.6 at % and 2.0 at % or less.

Abstract: There is provided a nitride crystal substrate having a main surface and formed of group-III nitride crystal, wherein NIR/NElec, satisfies formula (1) below, which is a ratio of a carrier concentration NIR at a center of the main surface relative to a carrier concentration NElec: 0.5?NIR/NElec?1.5 . . . (1) where NIR is the carrier concentration on the main surface side of the nitride crystal substrate obtained based on a reflectance of the main surface measured by a reflection type Fourier transform infrared spectroscopy, and NElec is the carrier concentration in the nitride crystal substrate obtained based on a specific resistance of the nitride crystal substrate and a mobility of the nitride crystal substrate measured by an eddy current method.

Abstract: A piezoelectric stack, including: a substrate; an electrode film; and a piezoelectric film comprising an alkali niobium oxide of a perovskite structure represented by a composition formula of (K1-xNax)NbO3 (0<x<1), wherein an average light transmittance through the piezoelectric film in a wavelength region of visible light and near-infrared ray is 65% or more.

Abstract: Provided is a crystal laminate including: a crystal substrate formed from a monocrystal of group III nitride expressed by a compositional formula InxAlyGa1-x-yN (where 0?x?1, 0?y?1, 0?x+y?1), the crystal substrate containing at least any one of n-type impurity selected from the group consisting of Si, Ge, and O; and a crystal layer formed by a group III nitride crystal epitaxially grown on a main surface of the crystal substrate, at least any one of p-type impurity selected from the group consisting of C, Mg, Fe, Be, Zn, V, and Sb being ion-implanted in the crystal layer. The crystal laminate is configured in a manner such that an absorption coefficient of the crystal substrate for light with a wavelength of 2000 nm when the crystal substrate is irradiated with the light falls within a range of 1.8 cm?1 or more and 4.6 cm?1 or less under a temperature condition of normal temperature.

Abstract: There is provided a laminated substrate having a piezoelectric film, including: a substrate; and a piezoelectric film provided on the substrate interposing a base film, wherein the piezoelectric film has an alkali niobium oxide based perovskite structure represented by a composition formula of (K1-xNax)NbO3 (0<x<1) and preferentially oriented in (001) plane direction, and a sound speed of the piezoelectric film is 5100 m/s or more.

Abstract: A production apparatus for producing a structural body includes: a holding mechanism that holds a processing target in contact with an etching solution, the processing target including an etch region that is made of a Group III nitride, and on which photoelectrochemical etching is to be performed; a light emitting device that irradiates the processing target with first light for performing the photoelectrochemical etching; a light emitting device that irradiates the processing target with second light that has a wavelength longer than that of the first light; and a measurement device that measures reflected light resulting from the second light being reflected off a surface of the etch region.

Abstract: There is provided a laminated substrate having a piezoelectric film, including: a substrate; and a piezoelectric film provided on the substrate interposing a base film, wherein the piezoelectric film has an alkali niobium oxide based perovskite structure represented by a composition formula of (K1-xNax)NbO3 (0<x<1) and preferentially oriented in (001) plane direction, and a sound speed of the piezoelectric film is 5100 m/s or more.

Abstract: There is provided a semiconductor device, including: a substrate; a group III nitride layer on the substrate, the group III nitride layer containing group III nitride; and a recess on the group III nitride layer, the group III nitride layer including: a channel layer, and a barrier layer on the channel layer, thereby forming a two-dimensional electron gas in the channel layer, the barrier layer including: a first layer containing aluminum gallium nitride, and a second layer on the first layer, the second layer containing aluminum gallium nitride added with an n-type impurity, wherein the recess is formed by removing all or a part of a thickness of the second layer, and at least a part of a thickness of the first layer is arranged below the recess.

Abstract: There is provided a nitride semiconductor laminate, including: a substrate; an electron transit layer provided on the substrate and containing a group III nitride semiconductor; and an electron supply layer provided on the electron transit layer and containing a group III nitride semiconductor, wherein a surface force A of the electron supply layer acting as an attractive force for attracting a probe and a surface of the electron supply layer when measured using the probe consisting of a glass sphere with a diameter of 1 mm covered with Cr, is stronger than a surface force B of Pt when measured under the same condition, and an absolute value |A?B| of a difference between them is 30 ?N or more.

Abstract: There is provided a method for manufacturing a semiconductor structure, including: preparing a plate-like semiconductor structure; and inspecting the semiconductor structure, the inspection of the semiconductor further including: performing a measurement of irradiating a surface of the semiconductor structure with a light from a light source in an oblique direction to the surface, and detecting a reflected light reflected or scattered by the surface by a two-dimensional detector, at a plurality of locations within at least a predetermined range of the surface of the semiconductor structure, to acquire a reflected light distribution that is a distribution of an integrated value obtained by integrating intensity of the reflected light measured at the plurality of locations, with respect to a position at the detector; and fitting the reflected light distribution by a multiple Gaussian function obtained by adding at least a first Gaussian function and a second Gaussian function distributed more widely than the fi

Abstract: A method for manufacturing a structure, including photoelectrochemically etching an etching object, the photoelectrochemical etching of the etching object including: injecting an alkaline or acidic etching solution containing an oxidizing agent that receives electrons, into a rotatably held container in which an etching object at least whose surface is composed of group III nitride is held, and immersing the surface in the etching solution; irradiating the surface of the etching object held in the container with light in a stationary state of the etching object and the etching solution; and rotating the container to scatter the etching solution toward an outer peripheral side, thereby discharging the etching solution from the container, after the surface is irradiated with the light.

Abstract: There is provided a method for manufacturing a structure, including: forming a recess portion by performing a first etching to a surface of a member composed of Group III nitride; and flattening a bottom of the recess portion by performing a second etching to the bottom, wherein in forming the recess portion, a flat portion and a protruding portion are formed on the bottom of the recess portion, the protruding portion being raised with respect to the flat portion because it is less likely to be etched by the first etching than the flat portion, and in flattening the bottom, by etching the protruding portion by the second etching, the protruding portion is lowered.