Surface Analysis of Nanoscale Aluminium and Silicon Films Made by Electrodeposition in Ionic Liquids

Preparation and Characterization of Crystalline Silicon by Electrochemical Liquid-Liquid-Solid Crystal Growth in Ionic Liquid

The electrodeposition at low temperature for the direct growth of crystalline thin films without any templating agent in ionic liquid (IL) is a relatively new electrochemical synthetic strategy. This work studied the role of the deposition temperature, deposition time, and different working electrodes in the electrodeposition of crystalline Si thin films from the byproduct silicon tetrachloride in IL at low temperature. X-ray diffraction (XRD) revealed that the as-deposited Si films were crystalline at the temperature of 80 °C. Scanning electron microscopy (SEM) and Raman spectroscopy further indicated that the crystalline quality of the as-deposited silicon film was relatively the best when the electrodeposition time reached 1 h at the temperature of 100 °C; excessive electrodeposition would yield amorphous silicon on the surface of the as-deposit crystalline Si, which decreased the crystal quality of the Si film. The SEM and XRD, respectively, revealed that the crystal structure of Si yielded on e-InGa was significantly different from that produced on Ga and more impurities existed in the film. Research on the influence of these parameters on crystallinity and morphological characteristics of Si gives better control over the growth of crystalline Si thin films for specific applications.

Electrodeposition of Si from an Ionic Liquid Bath at Room Temperature in the Presence of Water

The electrochemical deposition of Si has been carried out in an ionic liquid medium in the presence of water in a limited dry nitrogen environment on highly oriented pyrolytic graphite (HOPG) at room temperature. It has been found that the presence of water in ionic liquids does not affect the available effective potential window to a large extent. Silicon has been successfully deposited electrochemically in the overpotential regime in two different ionic liquids, namely, BMImTf₂N and BMImPF₆, in the presence of water. Although a Si thin film has been obtained from BMImTf₂N; only distinguished Si crystals protected in ionic liquid droplets have been observed from BMImPF₆. The most important observation of the present investigation is that the Si precursor, SiCl₄, instead of undergoing hydrolysis, even in the presence of water, coexisted with ionic liquids, and elemental Si has been successfully electrodeposited.

Electrodeposition of crystalline silicon directly from silicon tetrachloride in ionic liquid at low temperature

Crystalline silicon was fabricated directly from silicon tetrachloride in ionic liquid at low temperature of 100 °C. SEM, TEM and SEAD revealed that as-deposited crystalline Si with diamond cubic crystal structure.

Synthesis of Silicon and Germanium Nanowire Assemblies by Template-Assisted Electrodeposition from an Ionic Liquid

We report on the template-assisted synthesis of silicon and germanium nanowires from the air- and water-stable ionic liquid, 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide ([Py1,4] TFSA). The synthesis was done by electrochemical deposition in the pores of a commercial track-etched polycarbonate membrane. After chemical dissolution of the polycarbonate membrane in dichloromethane, nanowire assemblies with a regular arrangement were obtained. Different lengths of nanowires can be obtained by varying the applied potential and the time of deposition. The nanowire assemblies were characterised by scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM/EDX). Our results show that the template-assisted electrochemical deposition approach in ionic liquids has the potential to easily synthesise germanium and silicon nanowire assemblies.