Nonlinear O pressure dependence of the initial oxide growth kinetics on Si(111) surfaces; Photoelectron spectroscopy observation and molecular orbital calculation of oxidation states

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

Oxygen pressure dependence of the initial oxide growth kinetics on Si(111)- 77 surfaces has been investigated by real-time photoelectron spectroscopy and molecular orbital (MO) calculations. A nonlinear relationship between initial oxidation rate and oxygen pressure was found, which is quite different from the linear results on Si(001)-2771 surfaces. It was also observed that a larger amount of oxygen adsorption species 3 were formed in the Si(111)-77 subsurface at higher leading to an obstacle for the diffusion of O atoms into Si bulk due to its high potential energy barrier. Further a reaction path of oxygen adsorption states on Si(111)- 77 surfaces at room temperature was proposed based on the experimental and theoretical calculation results.