OXIDATION OF A SI(001) SURFACE-MEDIATED BY REPETITIVE ADSORPTION DESORPTION CYCLES OF CS - A METASTABLE DEEXCITATION SPECTROSCOPY STUDY/

We have investigated, by metastable deexcitation spectroscopy (MDS), t he initial stage of SiOx/Si(001) interface formation with repetitive o xidation cycles consisting of promoted oxygen-uptake by preadsorbed ca esium followed by annealine. MDS spectra from Cs-adsorbed SiOx/Si(001) surfaces were similar to that from a Cs/Si(001) surface showing sharp Cs 6 (s) over tilde peaks just below E(F), although oxygen atoms are included at the former substrate surface. The Cs atoms at the former s urfaces played the same role of transferring electrons to oxygen enhan cing the oxygen uptake rate as that observed at the latter surface. We explored an evolution of the valence-band states at topmost atomic la yers in the progress of alkali-assisted oxidation.