Synthesis of TiO 2 –Al 2 O 3 and TiO 2 –Ta 2 O 5 composite nanotubes on planar Si substrates

Abstract

Morphological studies of TiO2–Al2O3 and TiO2–Ta2O5 nanocomposite nanotubes synthesised on silicon substrates are presented here. Nanocomposite Ti–Al and Ti–Ta thin films were deposited on silicon substrates via simultaneous multi-target sputtering of Ti and Al targets or Ti and Ta targets, followed by anodisation in a fluorinated electrolyte. By increasing the Al or Ta concentration in the sputtered films, the morphology of the anodised films is changed from tubular oxides (with ripples on the outer walls) to well-aligned porous oxides (smooth walls, near zero gap between walls). By increasing the concentrations of Ta, formation of random Y-branched porous oxides in the anodised films is demonstrated. These nanotubes were synthesised on a planar substrates making them suitable for integrated circuits.