Effects of sputtering power of Ti films on morphology of TiO2 nanotubes synthesized via anodization process

In this paper, we aimed to find the sputtering power most suitable for fabricating anodized TiO2 nanotubes (TNTs) with high dimensions (diameter and length). TNTs were synthesized via anodization of Ti films deposited on a glass substrate at varying sputtering power from 50 W to 200 W. The properties of Ti films such as crystallinity, residual stress, and roughness were investigated, which affected the morphology of TNTs. Sputtering power levels of 150 W and 200 W were suitable for TNTs formation via the anodization process in NH4F concentrations from 1.0 wt% to 2.5 wt% due to the increased density and crystallinity of Ti films. Boosting the sputtering power to 200 W increases the roughness of the surface, resulting in a decrease in tube diameter and length. Increasing the sputtering power to 200 W also causes the residual stress of the film to be converted from compression to tensile stress, which allows for more TNTs structures to be formed on the film. Nanotubes fabricated on 150 W sputtered films have been proven to be superior to those fabricated at 200 W in every NH4F concentration in terms of length and diameter. Thus, they are more suitable for applications.