Electrodeposition of Nanoscale SixGe1-x from an Air- and Water Stable Ionic Liquid

Abstract

We report for the first successful electrodeposition of highly pure SixGe1-x from the air- and water stable ionic liquid 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide ([Py1,4]Tf2N) containing GeCl4 and SiCl4 as precursors. The electrodeposition is investigated by cyclic voltammetry and high resolution scanning electron microscopy. SixGe1-x can be deposited reproducibly and easily in this ionic liquid. Interestingly, the SixGe1-x deposit showed a strong colour change (from red to blue) at room temperature during electrodeposition. The observed colours are strong hints for band gaps between at least 1.5 and 3.2 eV, which are indicative of a quantum size effect. This proves the potential of ionic liquids in the electrodeposition of high quality SixGe1-x.