Patent ID: 7776304

Claim:
A process for preparing an aggregated crystalline silicon powder comprising: subjecting at least one vaporous or gaseous silane, an inert gas, hydrogen and optionally at least one vaporous or gaseous doping material, to heat in a hot wall reactor to form a reaction mixture comprising a product and gaseous substances, cooling the reaction mixture and separating the reaction product from the gaseous substances in the form of the aggregated crystalline silicon powder, wherein a proportion of the at least one silane is from 0.1 to 90 wt. %, with respect to the sum of the at least one silane, the optional at least one doping material, the hydrogen and the inert gases, a proportion of the hydrogen, with respect to the sum of the hydrogen, the at least one silane, the inert gas and the optional at least one doping material is in the range of from 1 mol. % to 96 mol. %, and the aggregated crystalline silicon powder has a BET surface area of 20 to 150 m 2 /g.