TEM characterization of super-hydrophilic Ni–Ti thin film

A super-hydrophilic Ni–Ti thin film is evaluated using cross-sectional transmission electron microscopy (TEM). Following sputter deposition and annealing, the Ni–Ti thin films are chemically treated with buffered oxide etchant, nitric acid and 30% hydrogen peroxide solution to produce a 100-nm-thick surface oxide layer. The fabricated Ni–Ti thin films show a 10- to 15-nm TiO2 thick layer on its surface with a ~ 67° wetting angle. For the surface treated sample, a porous oxide 100 nm TiO layer is found with a < 5°. It is believed that TiOOH(H2O)n complex forms on the surface to produce the observed super-hydrophilic behavior.