Abstract: For a semiconductor laser, a stacked member comprising an active layer is formed on the surface of a GaN single-crystal substrate, a defect aggregation portion is formed on the rear face of the GaN single-crystal substrate, and an electrode is formed so as to be electrically connected to the defect aggregation portion on the rear face. The defect aggregation portion of this semiconductor laser has numerous crystal defects, and so the carrier concentration is high, and the electrical resistivity is lowered significantly. For this reason, in a semiconductor laser of this invention in which an electrode is formed on this defect aggregation portion, an Ohmic contact can easily be obtained between the GaN single-crystal substrate and the electrode, and by this means a lowered driving voltage is realized.

Abstract: A fabrication method of a group III nitride crystal substance includes the steps of cleaning the interior of a reaction chamber by introducing HCl gas into the reaction chamber, and vapor deposition of a group III nitride crystal substance in the cleaned reaction chamber. A fabrication apparatus of a group III nitride crystal substance includes a configuration to introduce HCl gas into the reaction chamber, and a configuration to grow a group III nitride crystal substance by HVPE. Thus, a fabrication method of a group III nitride crystal substance including the method of effectively cleaning deposits adhering inside the reaction chamber during crystal growth, and a fabrication apparatus employed in the fabrication method are provided.

Abstract: A fabrication method of a group III nitride crystal substance includes the steps of cleaning the interior of a reaction chamber by introducing HCl gas into the reaction chamber, and vapor deposition of a group III nitride crystal substance in the cleaned reaction chamber. A fabrication apparatus of a group III nitride crystal substance includes a configuration to introduce HCl gas into the reaction chamber, and a configuration to grow a group III nitride crystal substance by HVPE. Thus, a fabrication method of a group III nitride crystal substance including the method of effectively cleaning deposits adhering inside the reaction chamber during crystal growth, and a fabrication apparatus employed in the fabrication method are provided.

Abstract: A GaN crystal substrate has a crystal growth surface on which a crystal is grown, and a rear surface opposite to the crystal growth surface. The crystal growth surface has a roughness Ra(C)of at most 10 nm, and the rear surface has a roughness Ra(R) of at least 0.5 ?m and at most 10 ?m. A ratio Ra(R)/Ra(C) of the surface roughness Ra(R) to the surface roughness Ra(C) is at least 50. Thus, a GaN crystal substrate of which front and rear surfaces are distinguishable from each other is provided, without impairing the morphology of a semiconductor layer grown on the GaN crystal substrate.

Abstract: A GaN substrate having a large diameter of two inches or more by which a semiconductor device such as a light emitting element with improved characteristics such as luminance efficiency, an operating life and the like can be obtained at low cost industrially, a substrate having an epitaxial layer formed on the GaN substrate, a semiconductor device, and a method of manufacturing the GaN substrate are provided. A GaN substrate has a main surface and contains a low-defect crystal region and a defect concentrated region adjacent to low-defect crystal region. Low-defect crystal region and defect concentrated region extend from the main surface to a back surface positioned on the opposite side of the main surface. A plane direction [0001] is inclined in an off-angle direction with respect to a normal vector of the main surface.

Abstract: There is provided a method of producing a thin GaN film-joined substrate, including the steps of: joining on a GaN bulk crystalline body a substrate different in type or chemical composition from GaN; and dividing the GaN bulk crystalline body at a plane having a distance of at least 0.1 ?m and at most 100 ?m from an interface thereof with the substrate different in type, to provide a thin film of GaN on the substrate different in type, wherein the GaN bulk crystalline body had a surface joined to the substrate different in type, that has a maximum surface roughness Rmax of at most 20 ?m. Thus a GaN-based semiconductor device including a thin GaN film-joined substrate including a substrate different in type and a thin film of GaN joined firmly on the substrate different in type, and at least one GaN-based semiconductor layer deposited on the thin film of GaN, can be fabricated at low cost.

Abstract: A method for concentration of fine particles dispersed in a dispersion into an ionic liquid comprising, adding an ionic liquid, especially an organic ionic liquid at ordinary temperature, e.g., a salt of 1-butyl-3-methylimidazolium with PF6? to a dilute dispersion of fine particles so as to concentrate the fine particles into the ionic liquid.

Abstract: There is provided a method of producing a thin GaN film-joined substrate, including the steps of: joining on a GaN bulk crystalline body a substrate different in type or chemical composition from GaN; and dividing the GaN bulk crystalline body at a plane having a distance of at least 0.1 ?m and at most 100 ?m from an interface thereof with the substrate different in type, to provide a thin film of GaN on the substrate different in type, wherein the GaN bulk crystalline body had a surface joined to the substrate different in type, that has a maximum surface roughness Rmax of at most 20 ?m. Thus a GaN-based semiconductor device including a thin GaN film-joined substrate including a substrate different in type and a thin film of GaN joined firmly on the substrate different in type, and at least one GaN-based semiconductor layer deposited on the thin film of GaN, can be fabricated at low cost.

Abstract: An active layer 17 is provided so as to emit light having a light emission wavelength in the range of 440 to 550 nm. A first conduction type gallium nitride-based semiconductor region 13, the active layer 17, and a second conduction type gallium nitride-based semiconductor region 15 are disposed in a predetermined axis Ax direction. The active layer 17 includes a well layer composed of hexagonal InXGa1-XN (0.16?X?0.35, X: strained composition), and the indium composition X is represented by a strained composition. The a-plane of the hexagonal InXGa1-XN is aligned in the predetermined axis Ax direction. The thickness of the well layer is in the range of more than 2.5 nm to 10 nm. When the thickness of the well layer is set to 2.5 nm or more, a light emitting device having a light emission wavelength of 440 nm or more can be formed.

Abstract: An active layer (17) is provided so as to emit light having an emission wavelength in the 440 nm to 550 nm band. A first-conductivity-type gallium nitride semiconductor region (13), the active layer (17), and a second-conductivity-type gallium nitride semiconductor region (15) are arranged along a predetermined axis (Ax). The active layer (17) includes a well layer composed of hexagonal InxGa1-xN (0.16?x?0.4, x: strained composition), with the indium fraction x represented by the strained composition. The m-plane of the hexagonal InxGa1-xN is oriented along the predetermined axis (Ax). The well-layer thickness is between greater than 3 nm and less than or equal to 20 nm. Having the well-layer thickness be over 3 nm makes it possible to fabricate light-emitting devices having an emission wavelength of over 440 nm.

Abstract: A fabrication method of a group III nitride crystal substance includes the steps of cleaning the interior of a reaction chamber by introducing HCl gas into the reaction chamber, and vapor deposition of a group III nitride crystal substance in the cleaned reaction chamber. A fabrication apparatus of a group III nitride crystal substance includes a configuration to introduce HCl gas into the reaction chamber, and a configuration to grow a group III nitride crystal substance by HVPE. Thus, a fabrication method of a group III nitride crystal substance including the method of effectively cleaning deposits adhering inside the reaction chamber during crystal growth, and a fabrication apparatus employed in the fabrication method are provided.

Abstract: A fabrication method of a group III nitride crystal substance includes the steps of cleaning the interior of a reaction chamber by introducing HCl gas into the reaction chamber, and vapor deposition of a group III nitride crystal substance in the cleaned reaction chamber. A fabrication apparatus of a group III nitride crystal substance includes a configuration to introduce HCl gas into the reaction chamber, and a configuration to grow a group III nitride crystal substance by HVPE. Thus, a fabrication method of a group III nitride crystal substance including the method of effectively cleaning deposits adhering inside the reaction chamber during crystal growth, and a fabrication apparatus employed in the fabrication method are provided.

Abstract: A group-III nitride light-emitting device is provided. An active layer having a quantum well structure is grown on a basal plane of a gallium nitride based semiconductor region. The quantum well structure is formed in such a way as to have an emission peak wavelength of 410 nm or more. The thickness of a well layer is 4 nm or more, and 10 nm or less. The well layer is composed of InXGa1-XN (0.15?X<1, where X is a strained composition). The basal plane of the gallium nitride based semiconductor region is inclined at an inclination angle within the range of 15 degrees or more, and 85 degrees or less with reference to a {0001} plane or a {000-1} plane of a hexagonal system group III nitride. The basal plane in this range is a semipolar plane.

Abstract: A method for fabricating metal-coated organic crystal wherein a reaction of an organic crystal with transition metal salt in alkaline aqueous solution under visible light irradiation, wherein, when energy at the top of valence band of the organic crystal is defined as A (eV) and energy at the bottom of conduction band of the organic crystal is defined as B (eV), redox potential C (V) of transition metal ion or transition metal complex ion, when said transition metal salt is dissolved in the alkaline aqueous solution, these three parameters should satisfy the following relation (1): ?A?4.5?C??B?4.

Abstract: A method of concentrating nanoparticles, having the steps of: adding and mixing an extraction solvent with a nanoparticles-dispersion liquid that nanoparticles are dispersed in a dispersion solvent, thereby concentrating and extracting the nanoparticles into a phase of the extraction solvent, and removing the dispersion solvent by filter-filtrating a liquid of concentrated extract, in which the extraction solvent is substantially incompatible with the dispersion solvent, and the extract solvent can form an interface after the extraction solvent is mixed with the dispersion solvent and left the mixture still; further a method of deaggregating aggregated nanoparticles, having the steps of: applying two or more ultrasonic waves different in frequency to a liquid containing aggregated nanoparticles, and thereby fining and dispersing the aggregated nanoparticles.

Abstract: The present invention relates to a method of preparing solid particulates and solid particulates prepared by using the method. The method of preparing solid particulates includes dissolving an organic or inorganic compound in a first solvent to provide an organic or inorganic compound-included solution, dispersing the organic or inorganic compound-included solution in a second solvent to provide an emulsion, and concentrating the emulsion in a dispersing medium to precipitate the organic or inorganic compound as solid particulates to provide a dispersion including the solid particulates. The first solvent is an organic solvent or an aqueous solvent, and the second solvent is an organic solvent or an aqueous solvent that is not compatible with the first solvent.

Abstract: Affords a GaN substrate from which enhanced-emission-efficiency light-emitting and like semiconductor devices can be produced, an epi-substrate in which an epitaxial layer has been formed on the GaN substrate principal surface, a semiconductor device, and a method of manufacturing the GaN substrate. The GaN substrate is a substrate having a principal surface with respect to whose normal vector the [0001] plane orientation is inclined in two different off-axis directions.

Abstract: A GaN substrate having a large diameter of two inches or more by which a semiconductor device such as a light emitting element with improved characteristics such as luminance efficiency, an operating life and the like can be obtained at low cost industrially, a substrate having an epitaxial layer formed on the GaN substrate, a semiconductor device, and a method of manufacturing the GaN substrate are provided. A GaN substrate has a main surface and contains a low-defect crystal region and a defect concentrated region adjacent to low-defect crystal region. Low-defect crystal region and defect concentrated region extend from the main surface to a back surface positioned on the opposite side of the main surface. A plane direction [0001] is inclined in an off-angle direction with respect to a normal vector of the main surface.

Abstract: In a semiconductor laser manufacturing method, a GaN single-crystal substrate is formed by slicing a GaN bulk crystal, grown on a c-plane, parallel to an a-plane which is perpendicular to the c-plane. In this substrate, crystal defects extending parallel to the c-axis direction do not readily exert an influence, and degradation of element characteristics due to crystal defects can be suppressed. Further, because the a-plane is a nonpolar plane, improved light emission efficiency and longer wavelengths can be achieved compared with the c-plane, which is a polar plane. Hence a semiconductor laser manufacturing method of this invention enables further improvement of the element characteristics of the semiconductor laser to be fabricated.

Abstract: For a semiconductor laser, a stacked member comprising an active layer is formed on the surface of a GaN single-crystal substrate, a defect aggregation portion is formed on the rear face of the GaN single-crystal substrate, and an electrode is formed so as to be electrically connected to the defect aggregation portion on the rear face. The defect aggregation portion of this semiconductor laser has numerous crystal defects, and so the carrier concentration is high, and the electrical resistivity is lowered significantly. For this reason, in a semiconductor laser of this invention in which an electrode is formed on this defect aggregation portion, an Ohmic contact can easily be obtained between the GaN single-crystal substrate and the electrode, and by this means a lowered driving voltage is realized.