Large-area silica nanotubes with controllable geometry on silicon substrates

The synthesis of a highly uniform, large-scale nanoarrays consisting of silica nanotubes above embedded nanohole arrays in silicon substrates is demonstrated. In situ anodized aluminium oxide (AAO) thin film masks on Si substrates were employed, and the nanotubes were fabricated by Ar ion milling through the masks. The geometries of the nanoarrays, including pore diameter, interpore distance and the length of both nanopores and nanotubes could be controlled by the process parameters, which included that the outer pore diameter of silica tube was tuned from ∼80nm to ∼135nm while the inner tube diameter from ∼40nm to ∼65nm, the interpore distance of the nanotube arrays was from 100nm to 180nm and the length of silica tube changed from ∼90nm to ∼250nm. The presented nanostructure fabrication method has strong potential for application in intensity and frequency adjustable high luminescence efficiency optoelectronic devices.