Electrodeposition of Si Thin Film in a Hydrophobic Room-Temperature Molten Salt

A possible way to electrodeposit Si has been studied in trimethyl--hexylammonium bis(trifluoromethylsulfonyl)imide containing . Cyclic voltammetry suggests that should be reduced to form Si at around . 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.