Detection of molecular oxygen adsorbate during room-temperature oxidation of Si(100)2 ' 1 surface: In situ synchrotron radiation photoemission study

Synchrotron radiation photoelectron spectroscopy during the oxidation of a Si(100)2 ' 1 surface at room temperature revealed the existence of molecularly adsorbed oxygen, which was considered to be absent. The O 1s spectrum of such oxidation was found to be similar to that of Si(111)7 ' 7 surface oxidation. Also, molecular oxygen appeared after the initial surface oxides were formed, indicating that it was not a precursor for dissociation oxygen adsorption on a clean surface. Considering this finding, we have proposed presumable structural models for atomic configurations, where molecular oxygen resided on the oxidized silicon with two oxygen atoms at the backbonds.