Electrode assemblies useful, inter alia, for mounting thin rods in Siemens reactors for manufacture of polysilicon, have a base segment which receives a holder segment, and an insert, interfacial surface(s) of which have depressions and/or elevations which reduce contact surface area, allowing the holder, base segment, insert, and optional intermediate segments to be constructed of materials having different thermal conductivities.

Electrode assemblies useful, inter alia, for mounting thin rods in Siemens reactors for manufacture of polysilicon, have a base segment which receives a holder segment, and an insert, interfacial surface(s) of which have depressions and/or elevations which reduce contact surface area, allowing the holder, base segment, insert, and optional intermediate segments to be constructed of materials having different thermal conductivities.

Chlorosilanes of the general formula H.sub.nSiCl.sub.4-n and/or H.sub.mCl.sub.6-mSi.sub.2, where n=1-4 and m=0-4, are produced in a fluidized bed reactor by reaction of a hydrogen chloride-containing reaction gas with a silicon contact mass granulation mixture composed of a coarse grain fraction and a fine grain fraction, wherein the average particle size of the fine grain fraction d.sub.50,fine is smaller than the average particle size of the coarse grain fraction d.sub.50,coarse.

Chlorosilanes of the general formula H.sub.nSiCl.sub.4-n and/or H.sub.mCl.sub.6-mSi.sub.2, where n=1-4 and m=0-4, are produced in a fluidized bed reactor by reaction of a hydrogen chloride-containing reaction gas with a silicon contact mass granulation mixture composed of a coarse grain fraction and a fine grain fraction, wherein the average particle size of the fine grain fraction d.sub.50,fine is smaller than the average particle size of the coarse grain fraction d.sub.50,coarse.

A support substrate 2 is a polycrystalline SiC substrate formed of polycrystalline SiC. Assuming that one of the two sides of the polycrystalline SiC substrate is a first side and that the other side is a second side, a substrate grain size change rate of the polycrystalline SiC substrate, which is a value obtained by dividing a difference between the average value of crystal grain sizes of the polycrystalline SiC on the first side and the average value of crystal grain sizes of the polycrystalline SiC on the second side by a thickness of the polycrystalline SiC substrate, is 0.43% or less. A radius of curvature of the polycrystalline SiC substrate is 142 m or more.

A support substrate 2 is a polycrystalline SiC substrate formed of polycrystalline SiC. Assuming that one of the two sides of the polycrystalline SiC substrate is a first side and that the other side is a second side, a substrate grain size change rate of the polycrystalline SiC substrate, which is a value obtained by dividing a difference between the average value of crystal grain sizes of the polycrystalline SiC on the first side and the average value of crystal grain sizes of the polycrystalline SiC on the second side by a thickness of the polycrystalline SiC substrate, is 0.43% or less. A radius of curvature of the polycrystalline SiC substrate is 142 m or more.

An intermediate structure for forming a semiconductor device and method of making is provided. The intermediate device includes (i) a substrate comprising a Ga-based layer, and (ii) optionally, a metal layer on the substrate; wherein at least one of the Ga-based layer and, if present, the metal layer comprises at least a surface region having an isoelectric point of less than 7, usually at most 6.

An intermediate structure for forming a semiconductor device and method of making is provided. The intermediate device includes (i) a substrate comprising a Ga-based layer, and (ii) optionally, a metal layer on the substrate; wherein at least one of the Ga-based layer and, if present, the metal layer comprises at least a surface region having an isoelectric point of less than 7, usually at most 6.

A component includes a film containing polycrystalline yttrium oxide. In an X-ray diffraction pattern of the film, a ratio I.sub.m/I.sub.c of a maximum intensity I.sub.m of a peak attributed to monoclinic yttrium oxide to a maximum intensity I.sub.c of a peak attributed to cubic yttrium oxide satisfies an expression: 0I.sub.m/I.sub.c0.002.

A novel CVD method for preparing a layer including refractory carbide crystals, silicon carbide crystals, wherein at least part of the layer is formed from a gas mixture containing a silicon source and an aromatic carbon source, wherein the molar C/Si ratio in said gas mixture is from about 0.85 to about 1.45. Also, layers obtainable by the method and their various uses and applications.