Electrochemical Processing of Nanoscale Si Thin Film in a Hydrophobic Room-Temperature Molten Salt

Abstract

The electrodeposition of silicon has been studied in trimethyl-n-hexylammonium bis(trifluoromethylsulfonyl)imide containing 0.1 M SiCl4. Cyclic voltammetric studies suggest that SiCl4 should be reduced around −2.0 V. Potentiostatic electrolysis at −2.0 V forms a yellowish-brown film on a Ni substrate. The results of energy dispersive X-ray spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy reveal that the electrodeposited film contains amorphous silicon. Part of the electrodeposited film surface was oxidized in the air during transportation from the glove box to the analysis apparatuses. However, the Si electrodeposited in the present system is much more stable than that in propylene carbonate containing 0.5 M SiCl4 and 0.1 M tetrabutylammonium chloride. Furthermore, highly uniform and dense thin film is obtained in the initial stage of electrolysis in the present system.