Phase transition of oxide growth on Si(111)77 studied by real-time photoelectron spectroscopy and theoretical calculations

Tang, J.*; Nishimoto, Kiwamu*; Ogawa, Shuichi*; Yoshigoe, Akitaka ; Ishizuka, Shinji*; Watanabe, Daiki*; Teraoka, Yuden; Takakuwa, Yuji*

To clarify the influence of adsorbed oxygen molecules; O in the oxidation of Si(111)77 surface, the initial oxidation kinetics were investigated by real-time photoelectron spectroscopy using He resonance line and synchrotron radiation at SPring-8, and theoretical calculations. The O2p uptakes indicate that Langmuir-type adsorption is in progress. When the supply of O gas was stopped at the oxide coverage of 50%, however, the O2p uptakes has almost no decrease and slightly decreased at 863 K and 883 K, respectively, while it steeply decreased at 913 K and eventually no oxide remained on Si(111) after 5000 s. O2p intensities decrease at slower rate when O supply was stopped at the larger oxide coverage. The observed changes of decomposition rate are ascribed to those of oxygen adsorption states. A surface reaction model is proposed to make clear the phase transition taking into account the role of O.