Synthesis of silicon nanowires by metal-catalyst-free 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 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. Si nanowires were synthesized by the sulfur-assisted thermal chemical vapor transport process without the using of any metal catalyst.