A photoelectron spectroscopy and photon stimulated desorption study of H₂O on Si(100) 2×1

We have studied H₂O adsorption on the Si(100) surface using photoelectron spectroscopy to record Si valence bands and Si 2p core level spectra; and photon stimulated desorption to record Si 2p edge total electron yield and H⁺‐ion yield spectra. We assign the valence‐band H₂O induced peaks at E_B=6.3 and 11.2 eV to the Si–OH and to the O–H bonds, respectively. The H₂O dosed Si 2p core level spectrum exhibits two H₂O induced equal intensity surface peaks with surface core level shifts of +0.25 and +1.00 eV that we assign to surface Si atoms in the Si–H and the Si–OH bonds, respectively. We interpret the features in the Si 2p edge H⁺‐ion yield spectrum as ion desorption from SiO₂ at surface defect minority sites. We conclude that H₂O adsorbs dissociatively as H and OH radicals on the Si(100) 2×1 surface dimers and that there are defect minority sites on the surface where H₂O adsorption causes SiO₂ formation.