Abstract
Using a new technique, highly organized TiO
2 nanotubular surfaces can be grown by the anodization of titanium on silicon substrates. The tubes are open at the top and their dimensions are given by the applied potential. The key to grow them is using temperatures close to 0
°C during anodization.
In this work, we present the self-organized formation of anodic TiO
2 nanotubular layers on flat and thin sputter-deposited layers of titanium on silicon. The TiO
2 nanotubes were grown by anodization of these substrates in HF/H
2SO
4 electrolytes at different potentials between 5
V and 20
V resulting in tubes with diameter ranging from 30 to 100
nm. The key to achieve an ordered layer from the thin film samples is to operate at low temperatures. This results in a conversion efficiency of Ti to TiO
2 nanotubes close to 100% and prevents loss of large amounts of the tubes due to chemical dissolution.