Silicon Nanowires Grown by Metal-Catalyst-Free VLS Process

The synthesis of single-crystal silicon (Si) nanowires by a metal-catalyst-free vapor-liquid-solid (VLS) process was studied. Silicon nanowires have been successfully synthesized by simple thermal treatment without any metal catalyst. For cases without metal catalysts, Si nanowires are grown by VLS processes assisted by sulfur. It is thought that sulfur instead of metals plays important role in this synthesis technique which is distinct from the conventional metal-catalytic VLS process. For the case without metal catalysts, single-crystal Si nanowires are grown by a VLS process in which the silicon sulfides produced by a reaction between Si and sulfur act as both molten eutectic alloy droplets and the source gases for nanowire growth.