Submonolayer (2×1) BaSi (001) and (2×1) SrSi (001) surface phases have been studied with normal Si(004) and off-normal Si(022) x-ray standing wave (XSW) measurements. These results are compared to previous XSW measurements of a (2×3) phase of Sr on Si(001). The (004) and (022) coherent positions indicate that alkaline-earth metal (AEM) atoms occupy the same type of high symmetry site in the (2×1) BaSi (001), (2×1) SrSi (001), and (2×3) SrSi (001) surface phases. The difference between the AEM adatom heights measured for the (2×1) BaSi (001) and (2×1) SrSi (001) phases is consistent with the difference in the ionic radii of Ba and Sr. Consideration of the nearest neighbor AEM-Si bond lengths that would result from AEM atoms sitting on symmetrically dimerized Si(001) at the height specified by the Ba and Sr coherent positions strongly suggests that the AEM atoms occupy valley-bridge sites.
|Original language||English (US)|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - 2005|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics