Electrodeposition of Si thin film in a hydrophobic room-temperature molten salt

A possible way to electrodeposit Si has been studied in trimethyl-n-hexylammonium bis(trifluoromethylsulfonyl)imide containing 0.1 mol L(-1) SiCl(4). Cyclic voltammetry suggests that SiCl(4) should be reduced to form Si at around -2.0 V. Potentiostatic electrolysis at this potential forms a yellowish-brown film on a Ni substrate. X-ray photoelectron spectroscopy and Raman spectroscopy reveal that the electrodeposited film contains amorphous Si. It is also found from scanning electron microscopy observation and energy-dispersive X-ray spectroscopy analysis that a highly uniform and dense thin film can be obtained in the initial stage of electrodeposition and that the electrodeposited Si film becomes rougher and thicker with the progress of electrolysis. (C) 2008 The Electrochemical Society.