The synthesis of silica nanowire arrays

Highly oriented silica nanowire arrays have been achieved as byproduct in the synthesis of GaN nanowires by the reaction of gallium with ammonium using In2O3 as catalyst. Resulting materials were characterized by field-emission scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). SEM images show that there are a few spheres and random nanowires distributed on the surface of the Si substrate. The spheres have a core/shell structure with nanowire arrays as shell layer. The nanowire arrays have uniform diameter about 60 nm with length about 15 μm. EDS data show that the nanowire arrays consist of only Si and O with a ratio of ∼1:1.8, whereas the cores of the spheres consist of Si, Ga and small amount of In. The random nanowires have uniform diameter about 50 nm with length up to 20 μm. EDS data indicate that only Ga and N with a ratio of ∼1:1 exists in the random nanowires, corresponding to the chemical composition of standard GaN.