A method for producing a Group III nitride semiconductor, includes: performing an ammonia treatment of supplying a gas containing ammonia to a surface of a substrate containing sapphire; subjecting the surface of the substrate to a heat treatment in a hydrogen-dominated atmosphere, after the ammonia treatment; nitriding the surface of the substrate by supplying a gas containing ammonia to the surface of the substrate, after the subjecting; and forming a crystal nucleus layer on the substrate by generating nuclei of GaN, AlGaN or AlN on the substrate, after the nitriding.

The present invention provides a polycrystalline SiC formed body having a low resistivity and a small variation in resistivity in a thickness direction thereof, and a method for producing the same. In the polycrystalline SiC formed body, a resistivity is 0.050 cm or less, and an average value of peak intensity ratios (A/B) is 0.040 or less, and a difference between an average of peak intensity ratios on a growth surface side and an average of peak intensity ratios on a substrate surface side is 0.040 or less, wherein A represents a peak intensity within a range of wavenumber of 950 to 970 cm.sup.1 of a Raman spectrum and B represents a peak intensity within a range of wavenumber of 780 to 800 cm.sup.1 in a Raman spectrum.

The present invention provides a polycrystalline SiC formed body having a low resistivity and a small variation in resistivity in a thickness direction thereof, and a method for producing the same. In the polycrystalline SiC formed body, a resistivity is 0.050 cm or less, and an average value of peak intensity ratios (A/B) is 0.040 or less, and a difference between an average of peak intensity ratios on a growth surface side and an average of peak intensity ratios on a substrate surface side is 0.040 or less, wherein A represents a peak intensity within a range of wavenumber of 950 to 970 cm.sup.1 of a Raman spectrum and B represents a peak intensity within a range of wavenumber of 780 to 800 cm.sup.1 in a Raman spectrum.

A method of the vapor-phase deposition of a sulfide layer of a transition metal by ALD according to the following cycle: exposing a substrate to a precursor of the transition metal, whereby an intermediate layer is formed, purging the reactor, exposing the intermediate layer to a precursor of sulfur, purging the reactor, the substrate being at a temperature in the range from 20 C. to 250 C. during the cycle, where the cycle can be repeated several times with the same precursors or with different precursors, the precursor of the transition metal being selected from among molybdenum oxyhalides, tungsten oxyhalides, vanadium halides, niobium halides, and tantalum halides.

A method of the vapor-phase deposition of a sulfide layer of a transition metal by ALD according to the following cycle: exposing a substrate to a precursor of the transition metal, whereby an intermediate layer is formed, purging the reactor, exposing the intermediate layer to a precursor of sulfur, purging the reactor, the substrate being at a temperature in the range from 20 C. to 250 C. during the cycle, where the cycle can be repeated several times with the same precursors or with different precursors, the precursor of the transition metal being selected from among molybdenum oxyhalides, tungsten oxyhalides, vanadium halides, niobium halides, and tantalum halides.

A reaction furnace for producing a polycrystalline silicon rod, the interior of which is hermetically sealed by a bell jar and a bottom plate, wherein the bottom plate is provided with a plurality of electrode pairs for holding a silicon core wire and energizing the silicon core wire, and the bottom plate is further provided with a plurality of gas supply nozzles, each with a tip jet upward, for supplying a starting material gas for silicon deposition into the interior space of the bell jar, characterized in that at least a part of the surface of the gas supply nozzles in contact with the interior space of the bell jar is composed of quartz including a roughened surface area having a ten point average roughness Rz of 1.0-5.0 m.

A reaction furnace for producing a polycrystalline silicon rod, the interior of which is hermetically sealed by a bell jar and a bottom plate, wherein the bottom plate is provided with a plurality of electrode pairs for holding a silicon core wire and energizing the silicon core wire, and the bottom plate is further provided with a plurality of gas supply nozzles, each with a tip jet upward, for supplying a starting material gas for silicon deposition into the interior space of the bell jar, characterized in that at least a part of the surface of the gas supply nozzles in contact with the interior space of the bell jar is composed of quartz including a roughened surface area having a ten point average roughness Rz of 1.0-5.0 m.

A processing method for a boule includes the following steps. The boule is moved to a first processing station of a grinding equipment, and a first grinding wheel located within the first processing station is utilized to perform a sidewall grinding process on a sidewall of the boule. During the sidewall grinding process, the boule rotates along a first rotational axis, and the first grinding wheel rotates along a second rotational axis, wherein the first rotational axis is parallel to the second rotational axis. The boule is moved to a second processing station of the grinding equipment, and a second grinding wheel located within the second processing station is utilized to perform a top surface grinding process on a top surface of the boule.

A silicon carbide crystal boule includes a flat surface, a truncated cone surface, and an annular curved surface. The annular curved surface connects the flat surface and the truncated cone surface. A width of the silicon carbide crystal boule gradually decreases from a first end of the truncated cone surface connecting the annular curved surface to a second end opposite to the first end.

A silicon carbide wafer having a seed end and a dome end opposite to the seed end. In the silicon carbide wafer, a basal plane dislocation (BPD) density detected by potassium hydroxide (KOH) etching is less than 550 pcs/cm.sup.2 at both the seed end and the dome end, and a basal plane dislocation (PL-BPD) density detected by photoluminescence is less than 2000 pcs/cm.sup.2 at both the seed end and the dome end.