Abstract: A Siemens type CVD reactor device is provided. One or more radiation shields are disposed between a rod filament and a cooled wall in the reactor. The radiation shield absorbs radiant heat emanating from the heated polysilicon rod during the CVD process, gets heated above 400° C., re-radiate the absorbed heat toward both of the polysilicon rod and the cooled wall, so as to provide thermal shielding effect to the cooled wall. The net energy loss of the polysilicon rod is reduced as much as the amount of energy emitted toward the polysilicon rod from the radiation shield, such that considerable amount of electrical energy of the CVD reactor is reduced and saved. The energy reduction rate goes up much higher if using multiple layered radiation shields, low shielding emissivity, and low thermal conductivity together. The purity of the manufactured polysilicon can be maintained by using thermal shielding material that is stable in a high temperature such as graphite, silicon carbide-coated graphite, and silicon.

Abstract: Polysilicon is deposited onto a tube or other hollow body. The hollow body replaces the slim rod of a conventional Siemens-type reactor and may be heated internally with simple resistance elements. The hollow body diameter is selected to provide a surface area much larger than that of a silicon slim rod. The hollow body material may be chosen such that, upon cooling, deposited polysilicon readily separates from the hollow body due to differences in contraction and falls into a collection container.

Abstract: Polysilicon dendrites are grown by depositing silicon on a polysilicon rod or other substrate. Surface temperature is increased to a temperature at which needle-like dendrites develop due to the deposition of silicon from silicon-containing molecules in the surrounding reactor atmosphere. Thereafter, the surface temperature is gradually reduced so that silicon that deposits on the needle-like dendrites causes the dendrites to grow and assume a generally flared shape.

Abstract: Polysilicon dendrites are grown by depositing silicon on a polysilicon rod or other substrate. Surface temperature is increased to a temperature at which needle-like dendrites develop due to the deposition of silicon from silicon-containing molecules in the surrounding reactor atmosphere. Thereafter, the surface temperature is gradually reduced so that silicon that deposits on the needle-like dendrites causes the dendrites to grow and assume a generally flared shape.

Abstract: The present invention is directed to a method for making substantially carbon-free polycrystalline silicon which comprises pyrolyzing a gaseous silicon compound on a heated starter filament mounted on a graphite chuck, said heated starter filament being maintained at a temperature sufficient to effect decomposition of the gaseous silicon compound to form polycrystalline silicon which is deposited thereon and by-product hydrogen, wherein the said graphite chuck is provided with a hydrogen impervious outer coating layer to prevent the by-product hydrogen from reacting with the graphite and form methane which decomposes as carbon on the deposited polycrystalline silicon.