Crystal Structure and Photocatalytic Activity of TiO2Films Deposited by Reactive Sputtering Using Ne, Ar, Kr, or Xe Gases

Titanium dioxide (TiO 2 ) films were deposited by r.f. reactive magnetron sputtering using four different sputtering gases, Ne, Ar, Kr, or Xe at a total gas pressure of 1.0 or 3.0 Pa. In the case of 1.0 Pa, the content of rutile phase markedly decreased and anatase content increased with increasing atomic mass of the sputtering gas where the crystallinity of anatase phase was much higher than that of rutile phase. In the case of 3.0 Pa, all the films were polycrystalline anatase TiO 2 without rutile phase. In any case, TiO 2 films with higher crystallinity exhibited higher photocatalytic activity.