Raman Spectroscopy Characterization of Dissolved Polysilicon Byproduct SiCl4 in Ionic Liquids

Silicon tetrachloride (SiCl 4 ) is the main byproducts of the polysilicon industries. The dissolution behaviors of SiCl 4 in imidazolium ionic liquid, including [Bmim]OTf, [Bmim]NTf 2 , [Hmim]NTf 2 , and [Omim]NTf 2 , were investigated for recycling Si from SiCl 4 . Raman spectroscopy was used to understand the combination between the ionic liquid and SiCl 4 , and the conductivity of ionic liquids in different conditions was determined. The results indicated that [Bmim]NTf 2 exhibited a better SiCl 4 dissolving capacity compared to [Bmim]OTf, longer alkyl chain lengths in the imidazolium cations of the ionic liquids exhibited a better performance in dissolving SiCl 4 , and [Bmim]NTf2 : PC = 1 : 2 exhibited the best conductivity. In addition, molecular bondings between C-Cl, Si-O-Si, and C-Si were formed between the ionic liquids and SiCl 4 .