Electrodeposition of Silicon from a Nonaqueous Solvent

Electroplating of silicon from solutions of SiHC13, SiCI4, SiBr4, Si(CHzCH3)~, Si(OCHzCH3)4, Si(OOCCH3)4, and Si[N(CH3)2] ~ in tetrahydrofuran, using LiC10~, TBAP, or TBAB as supporting electrolyte, has been studied. St--C, St--O, and Si--N bonds are not reduced. Cyclic voltammetry shows a reduction peak, followed by passivation, for the halogeno-silanes. Potentiostatic and galvanostatic deposition on Pt, Au, Ni, Cu glassy carbon, or ITO glass yields smooth layers up to 0.25 ~m. Thicker layers have cracks. Auger spectroscopy shows C (-8), O (-8), and C1 (-1.5) as impurities (atomic percent). An electrochemical si icon coating process would find appl ication in the field of corrosion protection and for the fabrication of low cost photovoltaic solar cells pro-vided the necessary material characterist ics could be met. A nonaqueous medium must be used for the electro-deposition of silicon because of its very large negative re-duct ion potential and the high reactivity of most of its