Regensburg 1998 – wissenschaftliches Programm
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O: Oberflächenphysik
O 14: Adsorption an Oberfl
ächen (II)
O 14.4: Vortrag
Dienstag, 24. März 1998, 12:00–12:15, H36
Surface structure analisis of O/alkali-metal/Si(111) with XSW — •C. Sánchez-Hanke1, A. Hille1, V. Eteläniemi2, E.G. Michel3, and G. Materlik1 — 1HASYLAB (Hamburger Synchrotronstrahlungs Labor) at (Deutsches Elektronen-Synchrotron), Notkestraße 85, Hamburg,Germany — 2Univ.Helsinki, Finland — 3Univ. Autónoma de Madrid, Spain
Oxygen/alkali-metal/semiconductor interfaces are interesting due to both their fundamental properties and their applications. There is a lot of information on their electronic properties, but only few studies have analyzed the geometric structure of these systems. We report a systematic investigation on the oxygen, alkali-metal (AM), and O/AM location on Si(111). To this end, we have combined the XSW (X-ray standing waves) technique using the XPS (X-ray Photoelectron spectroscopy) signal in order to detect simultaneously oxygen and AM signals. The measurements were performed at the BW1 beamline of HASYLAB. The Si(111)7×7 samples were covered with AM (Na,K) and subsequently exposed to oxygen (0.1 up to 2 L). Both the (111) and (220) substrate Bragg reflections were used to excite an XSW field. The Fourier components of the O and AM distribution function were used to determine the oxygen and AM adsorption sites. Two different components present in the oxygen 1s core level spectrum were independently analyzed and gave valence specific positions. A detailed geometrical model for the interface has been developed on the basis of these experimental data.