Effect of Nucleation Layer of Photocatalytic TiO2 Thin Film Prepared by Two-Step Deposition Using Radical-Assisted Sputtering

A nucleation layer forms in the nucleation step (the first step) of a two-step deposition method that we have developed for forming TiO 2 thin films. We found that the nucleation layer affects the crystallinity of TiO 2 thin films during the growth step (the second step). The crystallinity of the growth layer can be controlled by varying the kinetic energy of the sputter particles when they arrive at the substrate in the nucleation step. Since the nucleation density varies with the kinetic energy, the crystallinity is thought to improve, owing to the improvement in the nucleation density.