Fabrication of self-organized TiO2 nanotubes from columnar titanium thin films sputtered on semiconductor surfaces

Self-organized nanotube arrays of TiO2 have been grown from titanium (Ti) thin films deposited on p-type Si(100) substrates. Structural and morphological characterizations carried out by X-ray diffraction and scanning electron microcopy indicate that the sputtered crystalline Ti thin films used for subsequent anodization are hexagonally closed packed (hcp-Ti) and show a columnar morphology. Electrochemical anodization of the Ti films was carried out by potentiostatic experiments in 1 M H3PO4 + 1 M NaOH + 0.5 wt% HF electrolyte at room temperature. The TiO2 nanotubes on a semiconductor substrate have an average tube length of approximately 560 nut, diameter in the order of 80 nm and wall thickness approximately 20 nm. (c) 2006 Elsevier B.V. All rights reserved.