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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on SiBr4 by Materials Project

SiBr4 is Silicon tetrafluoride-like structured and crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four tetrabromosilane molecules. Si4+ is bonded in a tetrahedral geometry to four Br1- atoms. All Si–Br bond lengths are 2.21 Å. There are four inequivalent Br1- sites. In the first Br1- site, Br1- is bonded in a single-bond geometry to one Si4+ atom. In the second Br1- site, Br1- is bonded in a single-bond geometry to one Si4+ atom. In the third Br1- site, Br1- is bonded in a single-bond geometry to one Si4+ atom. In the fourth Br1- site, Br1- is bonded in a single-bond geometry to one Si4+ atom.

36 MATERIALS SCIENCE↗
NASA NTRS1979

The Production of Solar Cell Grade Silicon from Bromosilanes

A continuous Flow Reactor (CFR) process based on the hydrogen reduction of the bromosilanes SiBr4 and SiHBr3 was proposed. Initial experiments carried and directed at obtaining overall yield data for bromosilane reduction in the CFR, indicated the need for increased reactor residence time and deposition substrate particle packing density to fully characterize the kinetics (rate) and thermodynamics (yield) of observed silicon production. Fluidized bed experiments were therefore initiated to overcome these experimental difficulties, which showed both thermal decomposition and hydrogen reduction of SiHBr3 in a fluid bed reactor to present attractive closed-loop processes for producing solar cell grade polycrystalline silicon. No process selection could be made however due to the fact that preliminary optimization of 2 of 3 process stages in each case during the course of the experimental program showed comparable attainment of cost element objectives.

Schumacher, J. C.↗