VLS growth of Si nanocones using Ga and Al catalysts

Vapor–liquid–solid growth of needle-like silicon nanocones via atmospheric pressure chemical vapor deposition from SiCl4 and using Ga and Al catalysts is reported. Scanning electron microscopy and transmission electron microscopy reveal that the nanocones are composed of an oxide shell with a Si core. Energy dispersive spectroscopy along the length of the nanocones indicates that the catalyst is gradually consumed during the growth process, resulting in the needle-like morphology. Growth of the Si nanocones may occur via H2 reduction of SiCl4 at 950 °C, during which HCl(g) is generated as the reaction by-product. In this growth mechanism, the gradual etching of the Al/Ga catalyst by HCl leads to a gradual decrease of the catalyst volume, and hence the tapered Si nanowire morphology.