Ferrocene-activated growth of carbon-reinforced silica nanowires from a planar silica layer by chemical vapour deposition

In this letter, we report a simple procedure to synthesize carbon-reinforced silica fibres on planar silicon substrates covered with a thin silica cap layer. The procedure contains two steps, which are first activating the substrate with ferrocene and then exposing it to methane at ∼ 1100 °C, which transforms the silica cap layer into nanowires of ∼ 200 nm in diameter. The silica nanowires are reinforced by glassy carbon in the core, and have an optical band gap of ∼ 3.1 eV. During growth the nanowires are grown randomly inside circular areas surrounded by circular walls of large fibres, thus forming wreath-like patterns randomly distributed on the substrate surface. The growth of the nanowires and the formation mechanism of the wreath-like patterns are also discussed.