Template-assisted electrodeposition of SixGe1−xnanowires with varying length and composition from two different ionic liquids

Abstract

We have recently reported that “luminescent” Si_xGe_1−x can be electrodeposited from 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide ([Py_1,4]Tf₂N) at room temperature. Interestingly, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([EMIm]Tf₂N) ionic liquid delivers a germanium-rich Si_xGe_1−x showing also a quantum-size effect, as revealed in the present study. These results led us to evaluate the possibility of obtaining high quality Si_xGe_1−xnanowires from two different ionic liquids by the simple and inexpensive template-assisted electrochemical pathway. Herein, we report for the first time on the room temperature template synthesis of Si_xGe_1−xnanowires by potentiostatic electrochemical deposition from the air- and water-stable ionic liquids [Py_1,4]Tf₂N and [EMIm]Tf₂N containing (each) GeCl₄ and SiCl₄ as precursors. As a first step, a commercially available track-etched polycarbonate membrane (PC) with an average nominal pore diameter of 90 nm was used as template. Si_xGe_1−xnanowires with an average diameter corresponding to the nanopores' diameter and lengths of 1 to 2.5 µm were reproducibly obtained. [EMIm]Tf₂N delivers longer Si_xGe_1−xnanowires than [Py_1,4]Tf₂N under the same parameters and reaction conditions. Characterization of the nanowires was performed by EDX and HR-SEM.