Mechanisms of concurrent SiO desorption with oxide layer formation at Si(001) surface

Teraoka, Yuden; Yoshigoe, Akitaka ; Moritani, Kosuke*

Oxidation reactions at Si(001) surfaces have been studied via real-time in-situ photoemission spectroscopy with synchrotron radiation for chemical bonding states of Si and O atoms and mass spectrometry for desorption of SiO molecules with supersonic O molecular beams in a temperature region from 900 K to 1300 K. In this study, simultaneous measurements of Si 2p photoemission spectra and SiO desorption yield revealed that the decrease of SiO correlated with the increase of Si component, and the SiO desorption was terminated at the oxide thickness of 0.22 nm. These facts suggest that the SiO desorption takes place at the topmost Si dimers and a precursor for SiO desorption is so called a T site, in which O atoms are bonding with the dangling bonds of the dimers. Consequently, M1 and M2 in the Dual-Oxide-Species (DOS) model has been clarified to be a T site and an Si state, respectively.