A lithography-free method for producing freestanding one-dimensional gold nanoparticle arrays encapsulated within
silicon dioxide nanowires is reported. Silicon nanowires grown by the vapor-liquid-solid technique with diameters
ranging from 20 nm to 50 nm were used as the synthesis template. The gold nanoparticle arrays were obtained by coating
the surface of the silicon nanowires with a 10 nm gold film, followed by thermal oxidation in an oxygen ambient. It was
found that the thermal oxidation rate of the silicon nanowires was significantly enhanced by the presence of the gold thin
film, which fully converted the silicon into silicon dioxide. The gold-enhanced oxidation process forced the gold into the
core of the wire, forming a solid gold nanowire core surrounded by a silicon dioxide shell. Subsequent thermal treatment
resulted in the fragmentation of the gold nanowire into a uniformly spaced array of gold nanoparticles encapsulated by a
silicon dioxide shell, which was observed by in situ annealing in transmission electron microscopy. Analysis of many
different silicon nanowire diameters shows that the diameter and spacing of the gold nanopaticles follows the Rayleigh
instability, which confirms this is the mechanism responsible for formation of the nanoparticle array.
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