VLS growth of Si nanocones using Ga and Al catalysts

摘要

Vapor-liquid-solid growth of needle-like silicon nanocones via atmospheric pressure chemical vapor deposition from SiCl_4 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 H_2 reduction of SiCl_4 at 950 ℃, 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.