Abstract: An improved fluidized bed reactor and a method for utilizing the fluidized bed reactor in the production of, for example, high purity polycrystalline silicon, by the pyrolysis of silane containing gas. The reactor being characterized by an entrainment zone located above a lower reaction zone. The entrainment zone having a cross-sectional area less than or equal to the cross-sectional area of the reaction zone and being capable of maintaining a fluidization gas velocity sufficient to entrain silicon powder particles, yet not sufficient to entrain silicon particles.

Abstract: Polycrystalline silicon rod capable of providing within no more than two floating zoning passes, unicrystalline silicon exhibiting a resistivity of at least 10,000 ohm-cm (donor) and a lifetime of at least about 10,000 milliseconds, exhibits a copper X-ray diffraction pattern having a peak at 26.85.degree..+-.0.25.degree. (2 theta) and has less than 15 ppta boron and less than 20 ppta phosphorus.

Abstract: An improved fluidized bed reactor and a method for its use characterized by a variable thickness inert liner surrounding the fluidized bed reaction zone. Such liner generates heat that is transferred to the reaction zone. The heat is generated in the inert liner by passing an electrical current through the inert liner. The inert liner is thicker at the top than at the bottom and therefore more heat is generated at the bottom of the reaction zone than the top of the reaction zone due to the increased resistance of the thinner portions of the inert liner.

Abstract: The present invention is directed to an improved process for producing ultra high purity polycrystalline silicon which process provides for increased production capacity and electrical power efficiency. The process comprises recycling the exhaust gases of the silane pyrolysis reactor after the gases have been preferably first cooled and filtered utilizing a pocket-type reaction zone enclosure having a particular effective radius thereby effectively decreasing the amount of silicon powder formation. Preferably, the rate of recycle flow is sufficient to entrain silicon powder in the reactor and remove the powder from the reactor with the exiting exhaust gases.