Coexistence of passive and active oxidation for O2/Si(0 0 1) system observed by SiO mass spectrometry and synchrotron radiation photoemission spectroscopy

The Si18O desorption yield was measured in the Si(0 0 1) surface temperature region from 900 to 1300 K at the 18O2 incident energies of 0.7, 2.2 and 3.3 eV by using supersonic 18O2 molecular beams. The real-time in situ O 1s photoemission spectroscopy was performed during surface chemical reactions of the O2 molecules with the Si(0 0 1) surface. The increase of SiO desorption yield with increasing incident energy shown in a temperature region higher than 1000 K implies that the angular distribution of SiO desorption changes toward the forward direction in addition to the incident energy-induced backbond oxidation. In turn, the desorption yield increased with decreasing incident energy in a temperature region from 900 to 1000 K. Oxygen uptake curves obtained by the real-time in situ O 1s photoemission spectroscopy revealed the coexistence of the passive and the active oxidation. The formation of the oxide-nucleus and their growth due to the enhanced O2 sticking by the action of incident energy suppress the SiO desorption.