Formation of nanoporous titanium oxide films on silicon substrates using an anodization process

The formation of nanoporous TiO2 by anodization of titanium films deposited on silicon substrates was investigated. Films with homogeneously distributed pores having an average pore diameter of 25 nm and interpore distance of 40 nm were obtained by anodization in an aqueous HF electrolyte solution after a comprehensive investigation of the anodization conditions. It was shown that the magnitude of the anodization current and voltage have significant roles in the formation of different surface morphologies with different pore dimensions, ranging from big pits to nanosize porous structures. The study showed that the nanoporous structure is formed only in 0.5-1.0 wt% HF solution while keeping the anodizing potential at 3-5 V. The porous TiO2 films were characterized using scanning electron microscopy and x-ray diffraction techniques, and their formation conditions are discussed. In addition, a growth mechanism model is presented to explain the formation of different Surface structures.