A {100} indium phosphide (InP) wafer has multiplies of olive-shaped etch pits on the back side surface of the wafer, wherein the olive shape refers to a shape with its both ends being narrow and its middle being wide, e.g., an oval shape. A method of manufacturing the {100} indium phosphide wafer comprises: etching the wafer by immersing it into an etching solution to produce etch pits; washing the wafer with deionized water; protecting the back side surface of the wafer; mechanical polishing and chemical polishing the front side surface of the wafer, and then washing it with deionized water; de-protecting the back side surface of the wafer; wherein the etching solution comprises an acidic substance, deionized water and an oxidizing agent. The wafer can be heated uniformly during the epitaxial growth and thus displays good application effect.

A {100} indium phosphide (InP) wafer has multiplies of olive-shaped etch pits on the back side surface of the wafer, wherein the olive shape refers to a shape with its both ends being narrow and its middle being wide, e.g., an oval shape. A method of manufacturing the {100} indium phosphide wafer comprises: etching the wafer by immersing it into an etching solution to produce etch pits; washing the wafer with deionized water; protecting the back side surface of the wafer; mechanical polishing and chemical polishing the front side surface of the wafer, and then washing it with deionized water; de-protecting the back side surface of the wafer; wherein the etching solution comprises an acidic substance, deionized water and an oxidizing agent. The wafer can be heated uniformly during the epitaxial growth and thus displays good application effect.

Provided is an indium phosphide substrate having good accuracy of flatness of the orientation flat, and a method for producing the indium phosphide substrate. An indium phosphide substrate having a main surface and an orientation flat, wherein a difference between maximum and minimum values of a maximum height Pz in each of four cross-sectional curves is less than or equal to 1.50/10000 of a length in a longitudinal direction of an orientation flat end face, wherein the four cross-sectional curves are set at intervals of one-fifth of a thickness of the substrate on a surface excluding a width portion of 3 mm inward from both ends of the orientation flat end face in the longitudinal direction of the orientation flat end face, and the maximum height Pz in each of the four cross-sectional curves is measured in accordance with JIS B 0601:2013.

Provided is an indium phosphide substrate having good linearity accuracy of a ridge line where the main surface is in contact with the orientation flat, and a method for producing the indium phosphide substrate. An indium phosphide substrate having a main surface and an orientation flat, wherein a maximum value of deviation is less than 1/1000 of a length of a ridge line where the main surface is in contact with the orientation flat, when a plurality of measurement points are set at intervals of 2 mm from a start point to an end point at the ridge line, except for a length portion of 3 mm inward from both ends of the ridge line, and based on a reference line which is a straight line connecting the start point and the end point, a distance of each measurement point from the reference line is defined as the deviation of each measurement point.

Provided is an indium phosphide substrate having good linearity accuracy of a ridge line where the main surface is in contact with the orientation flat, and a method for producing the indium phosphide substrate. An indium phosphide substrate having a main surface and an orientation flat, wherein a maximum value of deviation is less than 1/1000 of a length of a ridge line where the main surface is in contact with the orientation flat, when a plurality of measurement points are set at intervals of 2 mm from a start point to an end point at the ridge line, except for a length portion of 3 mm inward from both ends of the ridge line, and based on a reference line which is a straight line connecting the start point and the end point, a distance of each measurement point from the reference line is defined as the deviation of each measurement point.

A method of manufacturing a diamond substrate includes: forming an ion implantation layer at a side of a main surface of a diamond seed substrate by implanting ions into the main surface of the diamond seed substrate; producing a diamond structure by growing a diamond growth layer by a vapor phase synthesis method on the main surface of the diamond seed substrate, after implanting the ions; and performing heat treatment on the diamond structure. The performed heat treatment causes the diamond structure to be separated along the ion implantation layer into a first structure including the diamond seed substrate and failing to include the diamond growth layer, and a diamond substrate including the diamond growth layer. Thus, the method of manufacturing a diamond substrate is provided that enables a diamond substrate with a large area to be manufactured in a short time and at a low cost.

A method of manufacturing a diamond substrate includes: forming an ion implantation layer at a side of a main surface of a diamond seed substrate by implanting ions into the main surface of the diamond seed substrate; producing a diamond structure by growing a diamond growth layer by a vapor phase synthesis method on the main surface of the diamond seed substrate, after implanting the ions; and performing heat treatment on the diamond structure. The performed heat treatment causes the diamond structure to be separated along the ion implantation layer into a first structure including the diamond seed substrate and failing to include the diamond growth layer, and a diamond substrate including the diamond growth layer. Thus, the method of manufacturing a diamond substrate is provided that enables a diamond substrate with a large area to be manufactured in a short time and at a low cost.

A silicon carbide substrate production method includes: the step of providing covering layers 1b, 1b, each containing silicon oxide, silicon nitride, silicon carbonitride, or silicide, respectively on both surfaces of a base material substrate 1a carbon, silicon or silicon carbide, and turning the surface of each of the covering layers 1b, 1b into a smooth surface to prepare a support substrate 1; a step of forming a polycrystalline silicon carbide film 10 on both surfaces of the support substrate 1 by a gas phase growth method or a liquid phase growth method; and a step of separating the polycrystalline silicon carbide films from the support substrate while preserving, on the surface thereof, the smoothness of the covering layer surfaces 1b, 1b by chemically removing at least the covering layers 1b, 1b, from the support substrate 1. The silicon carbide substrate has a smooth surface and reduced internal stress.

A silicon carbide substrate production method includes: the step of providing covering layers 1b, 1b, each containing silicon oxide, silicon nitride, silicon carbonitride, or silicide, respectively on both surfaces of a base material substrate 1a carbon, silicon or silicon carbide, and turning the surface of each of the covering layers 1b, 1b into a smooth surface to prepare a support substrate 1; a step of forming a polycrystalline silicon carbide film 10 on both surfaces of the support substrate 1 by a gas phase growth method or a liquid phase growth method; and a step of separating the polycrystalline silicon carbide films from the support substrate while preserving, on the surface thereof, the smoothness of the covering layer surfaces 1b, 1b by chemically removing at least the covering layers 1b, 1b, from the support substrate 1. The silicon carbide substrate has a smooth surface and reduced internal stress.

Prescribed mathematical expressions are satisfied, where ν.sub.0 represents a wave number indicating a peak corresponding to a folded mode of a longitudinal optical branch of a Raman spectrum of silicon carbide having a polytype of 4H and having zero stress, ν.sub.max represents a maximum value of a wave number indicating a peak corresponding to a folded mode of a longitudinal optical branch of a Raman spectrum of a silicon carbide substrate in a region from a first main surface to a second main surface, ν.sub.max represents a minimum value of the wave number indicating the peak corresponding to the folded mode of the longitudinal optical branch of the Raman spectrum, and ν.sub.1 represents a wave number indicating a peak corresponding to a folded mode of a longitudinal optical branch of a Raman spectrum of the silicon carbide substrate at the first main surface.