X-ray standing wave investigation of submonolayer barium and strontium surface phases on Si(001)

Journal Article · Mon Jul 19 04:00:00 EDT 2010 · Phys. Rev. B

OSTI ID:1008537

Goodner, D M; Marasco, D L; Escuadro, A A; Cao, L; Bedzyk, M J ^[1]

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1. NWU

Submonolayer (2 x 1) Ba/Si(001) and (2 x 1) Sr/Si(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 x 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 x 1) Ba/Si(001), (2 x 1) Sr/Si(001), and (2 x 3) Sr/Si(001) surface phases. The difference between the AEM adatom heights measured for the (2 x 1) Ba/Si(001) and (2 x 1) Sr/Si(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.

• Research Organization: Advanced Photon Source (APS), Argonne National Laboratory (ANL), Argonne, IL (US)
• Sponsoring Organization: USDOE
• OSTI ID: 1008537
• Journal Information: Phys. Rev. B, Journal Name: Phys. Rev. B Journal Issue: (16) ; 2005 Vol. 71; ISSN 1098-0121
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALKALINE EARTH METALS
ATOMS
BARIUM
BOND LENGTHS
STANDING WAVES
STRONTIUM
SYMMETRY