Fabrication of TiO2 nanotube on silicon substrate by two-step anodic oxidation for wafer level supercapacitors application

In this paper, TiO₂ nanotube arrays were tried to be fabricated on SiO₂/Si substrates by using "ultra weak" anodic oxidation with two-step method. We investigated the influence of key parameters on the structure of the TiO₂ nanotubes including potential, electrolyte and the oxidation time applied in two-step method. It is found that the morphology of the oxidized TiO₂ nanotube arrays was strongly affected by the oxidation conditions. In the experiment, the titanium film with thickness of 400 nm was firstly sputtered on SiO₂/Si substrates, and then low potentials of 10 V for 20 sec and 0.5 V for 25 min were respectively applied in HF solution with the low concentration of 0.05 wt%. The experimental results show that the dense TiO₂ nanotubes with diameters ranged from about 90 to 270 nm with an average value of 150 nm were obtained in the two-step anodic oxidation method. The obtained TiO₂ nanotubes with higher diameters are promising for manufacturing the micro supercapacitor with high specific surface area.