Synchrotron X-ray photoemission study of NiTi surface oxidation with hyperthermal oxygen molecular beam

Yamazaki, Daichi*; Sowa, Makoto*; Okada, Michio*; Teraoka, Yuden; Kasai, Toshio*

Dtailed studies on the initial oxidation process of NiTi with a 2 eV hyperthermal oxygen molecular beam (HOMB) and thermal O in the backfilling have been conducted. The oxidation processes are monitored by X-ray photoemission spectroscopic measurements in conjunction with synchrotron radiation. In the oxide formation process at higher oxygen coverage, HOMB has the advantage in the dissociation process of O molecule and can grow TiO layers with the underlying TiO-rich and/or Ni-rich layers even at room temperature. Surface annealing enhances the diffusion atoms and as a result, the efficiency of Ti oxide formation. We succeeded in fabricating thick Ni-free TiO layer, possibly blue colored rutile TiO, combining HOMB and surface annealing.