Electrodeposition of bismuth, tellurium, and bismuth telluride thin films from choline chlorideaoxalic acid ionic liquid

This article presents a series of preliminary results regarding the electrodeposition of bismuth, tellurium, and bismuth telluride films at 60 degree C from ionic liquids, containing a mixture of choline chloride and oxalic acid (ChClaOxA). Ten millimolar concentration solutions of BiCl3 and TeO2 were used as precursors in this supporting electrolyte. Cyclic voltammetry and electrochemical impedance spectroscopy techniques were used to demonstrate the deposition processes on Pt and Cu electrodes. Long-time electrolyses (30a120 min) performed at 60 degree C with potential control (between ?0.22 and ?0.37 V vs. Ag reference electrode) have resulted in films deposited on copper substrate. Film surfaces were studied by scanning electron microscopy and analyzed by energy dispersive X-ray spectroscopy. The results of this study show that ChClaOxA ionic liquid may be considered as a promising substitute of aqueous baths for Bi, Te or Bi2Te3 film plating.