Temperature dependence of morphologies of aligned silicon oxide nanowire assemblies catalyzed by molten gallium

Silicon oxide nanowire assemblies with fishbonelike, gourdlike, spindlelike, badmintonlike, and octopuslike morphologies were synthesized by the chemical vapor deposition of silane at 1150°C with molten gallium as the catalyst via a vapor-liquid-solid process. The morphologies of the nanowire assemblies were temperature-dependent so that within a specific temperature range nanowire assemblies with a specific morphology were formed. Although the nanowire assemblies formed in different temperature ranges have different morphologies, they all are composed of a spherical liquid-gallium ball (3 to 5 μm in diameter) and a silicon oxide nanowire bunch that grows out from the lower-hemisphere surface of the gallium ball. Branching-growth and batch-growth phenomena were observed in the samples and were believed to be responsible for the formation of the unique morphologies described here. The growth mechanism of the nanowire assemblies is discussed.