O pressure dependence of Si(111) surface oxidation states

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

Lifetime of metastable oxygen molecule (O) is so long on a Si(111)-77 surface that the reaction kinetics is significantly affected with respect to the saturated oxide thickness. In this study, dependence of oxygen adsorption states on the Si(111)-77 surface was investigated by photoelectron spectroscopy with changing surface sensitivity: work function, O 1s level, and O 2p bands to clarify the initial oxide growth kinetics. This is because the DAS structural model of Si(111)-77 is composed of three Si layers (about 1 nm) in depth, so that adsorbed oxygen is likely distributed down to 1 nm. Based on the dependence of oxygen adsorption states obtained from the curve fitting analysis of O 1s, we propose a reaction model of O adsorption on Si(111) by taking account of O.