High resolution X-ray photoelectron spectroscopy study on initial oxidation of 4H-SiC(0001)-()R30 surface

Takahashi, Shin*; Hatta, Shinichiro*; Yoshigoe, Akitaka ; Teraoka, Yuden; Aruga, Tetsuya*

An initial oxidation dynamics at 4H-SiC(0001)-()R30 surface has been studied using high resolution X-ray photoelectron spectroscopy and supersonic molecular beams. The clean surface was exposed to oxygen molecules with translational energy of 0.5 eV at 300 K. In the initial stage, oxygen molecules are immediately dissociated and atomic oxygens are inserted into Si-Si back bonds to form stable oxide species. At this stage, drastic increase in growth rate of stable oxide species was found by heating molecular beam source to 1400 K. We concluded that the increase of growth rate is mainly caused by molecular vibrational excitation. It suggests that the dissociation barrier is located in the exit channel on potential energy hypersurface. A metastable molecular oxygen species was also found to be adsorbed on a Si-adatom. The adsorption of the metastable species, however, is neither enhanced nor suppressed by molecular vibrational excitation.