Abstract: A semiconductor substrate has a main surface and formed of single crystal silicon carbide. The main surface includes a central area, which is an area other than the area within 5 mm from the outer circumference. When the central area is divided into square areas of 1 mm×1 mm, in any square area, density of dislocations of which Burgers vector is parallel to <0001> direction is at most 1×105 cm?2. Thus, a silicon carbide semiconductor substrate enabling improved yield of semiconductor devices can be provided.

Abstract: A method for producing a Group III nitride crystal includes the steps of cutting a plurality of Group III nitride crystal substrates 10p and 10q having a major surface from a Group III nitride bulk crystal 1, the major surfaces 10pm and 10qm having a plane orientation with an off-angle of five degrees or less with respect to a crystal-geometrically equivalent plane orientation selected from the group consisting of {20?21}, {20?2?1}, {22?41}, and {22?4?1}, transversely arranging the substrates 10p and 10q adjacent to each other such that the major surfaces 10pm and 10qm of the substrates 10p and 10q are parallel to each other and each [0001] direction of the substrates 10p and 10q coincides with each other, and growing a Group III nitride crystal 20 on the major surfaces 10pm and 10qm of the substrates 10p and 10q.

Abstract: A GaN single crystal substrate has a main surface with an area of not less than 10 cm2, the main surface has a plane orientation inclined by not less than 65° and not more than 85° with respect to one of a (0001) plane and a (000-1) plane, and the substrate has at least one of a substantially uniform distribution of a carrier concentration in the main surface, a substantially uniform distribution of a dislocation density in the main surface, and a photoelasticity distortion value of not more than 5×10?5, the photoelasticity distortion value being measured by photoelasticity at an arbitrary point in the main surface when light is applied perpendicularly to the main surface at an ambient temperature of 25° C. Thus, the GaN single crystal substrate suitable for manufacture of a GaN-based semiconductor device having a small variation of characteristics can be obtained.

Abstract: There are provided a Si(1-v-w-x)CwAlxNv substrate that achieves high crystallinity and low costs, an epitaxial wafer, and manufacturing methods thereof. A method for manufacturing a Si(1-v-w-x)CwAlxNv substrate according to the present invention includes the steps of preparing a different type of substrate 11 and growing a Si(1-v-w-x)CwAlxNv layer having a main surface on the different type of substrate 11. The component ratio x+v at the main surface of the Si(1-v-w-x)CwAlxNv layer is 0<x+v<1. The component ratio x+v increases or decreases monotonically from the interface between the Si(1-v-w-x)CwAlxNv layer and the different type of substrate 11 to the main surface of the Si(1-v-w-x)CwAlxNv layer. The component ratio x+v at the interface between the Si(1-v-w-x)CwAlxNv layer and the different type of substrate 11 is closer to that of the material of the different type of substrate 11 than the component ratio x+v at the main surface of the Si(1-v-w-x)CwAlxNv layer.

Abstract: A method of manufacturing a GaN-based film includes the steps of preparing a composite substrate, the composite substrate including a support substrate in which a coefficient of thermal expansion in its main surface is more than 0.8 time and less than 1.0 time as high as a coefficient of thermal expansion of GaN crystal in a direction of a axis and a single crystal film arranged on a main surface side of the support substrate, the single crystal film having threefold symmetry with respect to an axis perpendicular to a main surface of the single crystal film, and forming a GaN-based film on the main surface of the single crystal film in the composite substrate, the single crystal film in the composite substrate being an SiC film. Thus, a method of manufacturing a GaN-based film capable of manufacturing a GaN-based film having a large main surface area and less warpage without crack being produced in a substrate is provided.

Abstract: The present method of manufacturing a GaN-based film includes the steps of preparing a composite substrate, the composite substrate including a support substrate in which a coefficient of thermal expansion in a main surface is more than 0.8 time and less than 1.2 times as high as a coefficient of thermal expansion of GaN crystal in a direction of a axis and a single crystal film arranged on a side of the main surface of the support substrate, the single crystal film having threefold symmetry with respect to an axis perpendicular to a main surface of the single crystal film, and forming a GaN-based film on the main surface of the single crystal film in the composite substrate. Thus, a method of manufacturing a GaN-based film capable of manufacturing a GaN-based film having a large main surface area and less warpage is provided.

Abstract: A method for forming an epitaxial wafer is provided as one enabling growth of a gallium nitride based semiconductor with good crystal quality on a gallium oxide region. In step S107, an AlN buffer layer 13 is grown. In step S108, at a time t5, a source gas G1 containing hydrogen, trimethylaluminum, and ammonia, in addition to nitrogen, is supplied into a growth reactor 10 to grow the AlN buffer layer 13 on a primary surface 11a. The AlN buffer layer 13 is so called a low-temperature buffer layer. After a start of film formation of the buffer layer 13, in step S109 supply of hydrogen (H2) is started at a time t6. At the time t6, H2, N2, TMA, and NH3 are supplied into the growth reactor 10. A supply amount of hydrogen is increased between times t6 and t7, and at the time t7 the increase of hydrogen is terminated to supply a constant amount of hydrogen. At the time t7, H2, TMA, and NH3 are supplied into the growth reactor 10.

Abstract: A GaN single crystal substrate has a main surface with an area of not less than 10 cm2, the main surface has a plane orientation inclined by not less than 65° and not more than 85° with respect to one of a (0001) plane and a (000-1) plane, and the substrate has at least one of a substantially uniform distribution of a carrier concentration in the main surface, a substantially uniform distribution of a dislocation density in the main surface, and a photoelasticity distortion value of not more than 5×10?5, the photoelasticity distortion value being measured by photoelasticity at an arbitrary point in the main surface when light is applied perpendicularly to the main surface at an ambient temperature of 25° C. Thus, the GaN single crystal substrate suitable for manufacture of a GaN-based semiconductor device having a small variation of characteristics can be obtained.

Abstract: A method of manufacturing a GaN-based film includes the steps of preparing a composite substrate, the composite substrate including a support substrate in which a coefficient of thermal expansion in its main surface is more than 0.8 time and less than 1.0 time as high as a coefficient of thermal expansion of GaN crystal in a direction of a axis and a single crystal film arranged on a main surface side of the support substrate, the single crystal film having threefold symmetry with respect to an axis perpendicular to a main surface of the single crystal film, and forming a GaN-based film on the main surface of the single crystal film in the composite substrate, the single crystal film in the composite substrate being an SiC film. Thus, a method of manufacturing a GaN-based film capable of manufacturing a GaN-based film having a large main surface area and less warpage without crack being produced in a substrate is provided.

Abstract: The present method of manufacturing a GaN-based film includes the steps of preparing a composite substrate, the composite substrate including a support substrate in which a coefficient of thermal expansion in a main surface is more than 0.8 time and less than 1.2 times as high as a coefficient of thermal expansion of GaN crystal in a direction of a axis and a single crystal film arranged on a side of the main surface of the support substrate, the single crystal film having threefold symmetry with respect to an axis perpendicular to a main surface of the single crystal film, and forming a GaN-based film on the main surface of the single crystal film in the composite substrate. Thus, a method of manufacturing a GaN-based film capable of manufacturing a GaN-based film having a large main surface area and less warpage is provided.

Abstract: A silicon carbide crystal ingot having a surface greater than or equal to 4 inches, having an n-type dopant concentration greater than or equal to 1×1015 atoms/cm3 and less than or equal to 1×1020 atoms/cm3, a metal atom concentration greater than or equal to 1×1014 atoms/cm3 and less than or equal to 1×1018 atoms/cm3, and not exceeding the n-type dopant concentration, and a metal atom concentration gradient less than or equal to 1×1017 atoms/(cm3·mm), a silicon carbide single crystal wafer produced using the ingot, and a method for fabricating the silicon carbide crystal ingot.

Abstract: A single crystal silicon carbide substrate has a 4H-polytype crystal structure, has with nitrogen atoms doped as a conduction impurity with an atomic concentration of more than 1×1016/cm3, and has a main surface containing a circle having a diameter of 5 cm. The single crystal silicon carbide substrate includes only one of a facet region and a non-facet region. Thus, variation in nitrogen atom concentration in the single crystal silicon carbide substrate can be suppressed.

Abstract: A silicon carbide substrate has a first layer facing a semiconductor layer and a second layer stacked on the first layer. Dislocation density of the second layer is higher than dislocation density of the first layer. Thus, quantum efficiency and power efficiency of a light-emitting device can both be high.

Abstract: Toward making available III nitride crystal substrates advantageously employed in light-emitting devices, and light-emitting devices incorporating the substrates, a III nitride crystal substrate has a major face whose surface area is not less than 10 cm2 and is characterized by: edge dislocations in the crystal being concentrated along propagation lines forming an angle of some 0° to 5° with a given {0001} plane of the crystal; screw dislocations in the crystal being concentrated along propagation lines forming an angle of some 45° to 60° with the given {0001} plane; and in a major-face principal region excluding the peripheral margin of the major face from its outer periphery to a 5 mm separation from its outer periphery, the total dislocation density being between 1×104 cm?2 to 3×106 cm?2 inclusive, and the ratio of screw-dislocation density to the total dislocation density being 0.5 or greater.

Abstract: A method for producing a Group III nitride crystal includes the steps of cutting a plurality of Group III nitride crystal substrates 10p and 10q having a major surface from a Group III nitride bulk crystal 1, the major surfaces 10pm and 10qm having a plane orientation with an off-angle of five degrees or less with respect to a crystal-geometrically equivalent plane orientation selected from the group consisting of {20?21}, {20?2?1}, {22?41}, and {22?4?1}, transversely arranging the substrates 10p and 10q adjacent to each other such that the major surfaces 10pm and 10qm of the substrates 10p and 10q are parallel to each other and each [0001] direction of the substrates 10p and 10q coincides with each other, and growing a Group III nitride crystal 20 on the major surfaces 10pm and 10qm of the substrates 10p and 10q.

Abstract: There is provided a method for producing a silicon carbide crystal, including the steps of: preparing a mixture by mixing silicon small pieces and carbon powders with each other; preparing a silicon carbide powder precursor by heating the mixture to not less than 2000° C. and not more than 2500° C.; preparing silicon carbide powders by pulverizing the silicon carbide powder precursor; and growing a silicon carbide crystal on a seed crystal using the silicon carbide powders in accordance with a sublimation-recrystallization method, 50% or more of the silicon carbide powders used in the step of growing the silicon carbide crystal having a polytype of 6H.

Abstract: A GaN single crystal substrate has a main surface with an area of not less than 10 cm2, the main surface has a plane orientation inclined by not less than 65° and not more than 85° with respect to one of a (0001) plane and a (000-1) plane, and the substrate has at least one of a substantially uniform distribution of a carrier concentration in the main surface, a substantially uniform distribution of a dislocation density in the main surface, and a photoelasticity distortion value of not more than 5×10?5, the photoelasticity distortion value being measured by photoelasticity at an arbitrary point in the main surface when light is applied perpendicularly to the main surface at an ambient temperature of 25° C. Thus, the GaN single crystal substrate suitable for manufacture of a GaN-based semiconductor device having a small variation of characteristics can be obtained.

Abstract: A gallium nitride based semiconductor device is provided which includes a gallium nitride based semiconductor film with a flat c-plane surface provided on a gallium oxide wafer. A light emitting diode LED includes a gallium oxide support base 32 having a primary surface 32a of monoclinic gallium oxide, and a laminate structure 33 of Group III nitride. A semiconductor mesa of the laminate structure 33 includes a low-temperature GaN buffer layer 35, an n-type GaN layer 37, an active layer 39 of a quantum well structure, and a p-type gallium nitride based semiconductor layer 37. The p-type gallium nitride based semiconductor layer 37 includes, for example, a p-type AlGaN electron block layer and a p-type GaN contact layer. The primary surface 32a of the gallium oxide support base 32 is inclined at an angle of not less than 2 degrees and not more than 4 degrees relative to a (100) plane of monoclinic gallium oxide.

Abstract: Silicon carbide single crystal is prepared. Using the silicon carbide single crystal as a material, a silicon carbide substrate having a first face and a second face located at a side opposite to the first face is formed. In the formation of the silicon carbide substrate, a first processed damage layer and a second processed damage layer are formed at the first face and second face, respectively. The first face is polished such that at least a portion of the first processed damage layer is removed and the surface roughness of the first face becomes less than or equal to 5 nm. At least a portion of the second processed damage layer is removed while maintaining the surface roughness of the second plane greater than or equal to 10 nm.

Abstract: A GaN-crystal free-standing substrate obtained from a GaN crystal grown by HVPE with a (0001) plane serving as a crystal growth plane and at least one plane of a {10-11} plane and a {11-22} plane serving as a crystal growth plane that constitutes a facet crystal region, except for the side surface of the crystal, wherein the (0001)-plane-growth crystal region has a carbon concentration of 5×1016 atoms/cm3 or less, a silicon concentration of 5×1017 atoms/cm3 or more and 2×1018 atoms/cm3 or less, and an oxygen concentration of 1×1017 atoms/cm3 or less; and the facet crystal region has a carbon concentration of 3×1016 atoms/cm3 or less, a silicon concentration of 5×1017 atoms/cm3 or less, and an oxygen concentration of 5×1017 atoms/cm3 or more and 5×1018 atoms/cm3 or less.