Synthesis of silicon thin film by electrodeposition from ionic liquid

Abstract

The synthesis of a silicon thin film by room-temperature electrodeposition was investigated in the ionic liquids 1-ethyl-3-methyl-imidazolium bis(trifluoromethylsulfonyl)imide ([EMIM]Tf2N) and 1-butyl-3-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([BMPy]Tf2N) with SiCl4. Cyclic voltammetry on a gold working electrode showed the possibility of the electrodeposition of elemental silicon. The reduction current of silicon in [EMIM]Tf2N was higher than in [BMPy]Tf2N. The elemental silicon thin film could be synthesized on the gold electrode under potentiostatic conditions, as confirmed by various analytical techniques including X-ray diffraction, X-ray photoelectron spectroscopy, and scanning electron microscopy with energy-dispersive spectroscopy. In the [EMIM]Tf2N electrolyte with dissolved SiCl4, the electrodeposited Si surface was more uniform than in [BMPy]Tf2N and no impurity was detected except trace oxygen caused by contamination during handling for analysis.