Analysis of silicon nanowires grown by combining SiO evaporation with the VLS mechanism

Silicon nanowires have received increasing attention as potential building blocks for nanoscale devices. We report the growth and analysis of silicon nanowires consisting of a crystalline silicon core and a thick oxide shell, which were grown by evaporation of silicon monoxide (SiO) in an inert gas atmosphere using a gold-coated silicon wafer as a substrate. This method combines SiO evaporation with the vapor-liquid-solid (VLS) nanowire growth mechanism. The resulting nanowires were analyzed using scanning electron microscopy, transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDXS). The thick oxide shell was determined to be the product of the SiO evaporation and subsequent phase separation into Si and SiO2. The EDXS measurements confirmed the silicon core/oxide shell structure of the nanowires and the existence of a gold dot on the nanowire tip as required by the VLS mechanism. An explanation is proposed for growth of the nanowires by combination of the VLS mechanism and SiO disproportionation. High-resolution TEM micrographs show the crystalline structure of the nanowire silicon core. Some of the nanowires were found to show an oscillation in diameter. (C) 2004 The Electrochemical Society.