Barium adsorption on hydrogenated surfaces

This is the authors' abstract. We don't add key points for this paper.

An experimental study of Ba and H adsorption on by Auger electron spectroscopy, thermal desorption spectroscopy, low-energy electron diffraction, electron energy loss spectroscopy, and work function measurements has been made. Measurements of hydrogen adsorption on a clean silicon surface have been made mainly for reference purposes. H on Si forms two different states, known as monohydride state and dihydride state . Preadsorption of H made the surface order more stable without changing the sticking coefficient of Ba on the Si surface. The results supported the double-layer (DL) model for the first Ba layer on the monohydrided Si surface. Ba adatoms up to ML on the dihydride phase were relaxed at symmetric and equivalent sites following the symmetry of the restored Si surface. TDS measurements showed that during Ba adsorption on the monohydride phase some of the H atoms were removed from their initial adsorption sites, and a new H energy state was formed at which was attributed to the weakening of the Si - H bond in the presence of Ba adatoms. When Ba deposition took place on the dihydride phase, two new H states were successively developed. The first state at was attributed to formation, and the subsequent one to a complex Ba - H - Si compound near . The presence of hydrogen caused a considerable delay of barium overlayer metallization, in contrast to the early metallization of alkali on hydrogenated surfaces.