Photon-stimulated desorption study of a SiO, film surface

Photon-stimulated desorption (PSD) experiments on thermal oxide films on Si have been performed using synchrotron radiation with photon energies in the Si 2p core-level excitation region, to investigate the chemical nature of the film surface. Mass analysis of the PSD ions is performed using a time-of-flight technique. H ⁺ is found to be the dominant ion species that desorbs from the film surface. It is observed that the H ⁺PSD ion yield decreases exponentially with increasing the irradiation time of incident photons. The H ⁺PSD ion yield as a function of photon energy exhibits a close similarity in spectral shape to the photoabsorption spectrum of SiO₂. The present experimental results confirm us that hydrogen atoms exists on the outermost layer of SiO₂ film, and provide direct evidence for Si-OH and Si-H termination of SiO₂ films.