Oxidation of H-terminated Si(100) surfaces studied by high-resolution electron energy loss spectroscopy

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Abstract
The adsorption of oxygen on H‐terminated Si(100) surfaces has been investigated by high‐resolution electron energy loss spectroscopy (HREELS). Adsorptions of atomic oxygen occur even at room temperature. Si‐OH stretching and Si‐O‐Si (B1) vibrational modes are observed in HREELS spectra, which indicates that atomic oxygen is adsorbed on sites of Si—H bonds and Si—Si back bonds. On the other hand, H‐terminated surfaces are very stable for molecular oxygen, which cannot adsorb until 380 °C on the surface. A dissociative adsorption of molecular oxygen is observed above 380 °C and the activation energy of the adsorption is 2.0 eV at 380–450 °C. This value coincides with the desorption energy of hydrogen atoms from a Si(100) surface with the monohydride phase. These results indicate that the dangling bonds are essential to the adsorption of molecular oxygen on Si(100) surfaces.