Toward self-ordered silica nanotubes by electrochemical anodization of Si(100)

In the present work, we produce self-ordered silica nanostructures by anodization of p-type Si(100) wafers in dilute fluoride-containing organic electrolytes. The effects of water content, fluoride concentrations, and potential are investigated. In electrolytes containing sufficiently low water and fluoride concentrations, nanoporous and nanotubular structures can be formed. X-ray photoelectron spectroscopy and X-ray diffraction results confirm that the structures consist of SiO₂. Under optimized conditions, self-ordered nanotubular silica structures can be formed with individual tube diameters of ∼30 nm.