Temperature-dependent growth of germanium oxide and silicon oxide based nanostructures, aligned silicon oxide nanowire assemblies, and silicon oxide microtubes

We demonstrate the temperature-dependent growth of germanium oxide and silicon oxide based composite nanostructures (multiple nanojunctions of Ge nanowires and SiOx nanowires, Ge-filled SiO2 nanotubes, Gel SiO2 coaxial nanocables, and a variety of interesting rnicrometer-sizcd structures), aligned SiOx nanowire assemblies, and SiOx microtubes. The structures were characterized by SEM, TEM, energy-dispersive X-ray spectroscopy, and electron diffraction. The combination of laser ablation of a germanium target and thermal evaoporation of silicon monoxide powders resulted in the formation of Ge and SiOx species in a carrier gas; the nano/micro-sized structures grow by either a Ge-catalyzed vapor liquid-solid or a Ge-nanowire-templated vapor-solid process.