Metal surface nucleated supercritical fluid–solid–solid growth of Si and Ge/SiOx core–shell nanowires.

High yields of single-crystalline silicon nanowires and germanium/silicon oxide core-shell nanostructures were synthesized using a supercritical fluid-solid-solid growth mechanism. The formation of the one-dimensional nanostructures was investigated on stainless steel and titanium reactor cell walls. The nanowire growth is diffusion controlled with no catalyst particles being observed at the tip of the nanowires, which is contrary to the characteristic feature of a one-dimensional growth based on the vapor-liquid-solid mechanism.