Temperature dependence of the initial oxidation kinetics of Ti(0001) surface was investigated by low energy electron diffraction (LEED) and real-time photoelectron spectroscopy using synchrotron radiation of surface- and bulk-sensitive photon energies. LEED observation revealed that oxide layers grow epitaxially with different surface structures depending on temperature: 1×1 at 200oC and √3×√3 at 400oC. From the oxygen uptake curve measured by O 1s photoelectron intensity, it was clarified that oxygen diffusion through the epitaxially grown oxide layer is significantly enhanced with raising temperature, making the oxide layer thicker than 70 Å at 400oC. The chemical shift components observed for Ti 2p showed that TiO2 becomes predominant at the subsurface with O2 dose, while the stoichiometry of oxide near the interface is maintained as TiO and Ti2O3, for both cases at 200oC and 400oC. Thus it is concluded that the epitaxial growth of a very thin oxide on the Ti(0001) surface proceeds not only at the interface but also in the oxide layer by increasing the oxidation number to that of TiO2.
