Regensburg 2002 – wissenschaftliches Programm

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O: Oberflächenphysik

O 29: Adsorption an Oberfl
ächen (III)

O 29.3: Vortrag

Donnerstag, 14. März 2002, 11:45–12:00, H43

The structure of step-edge sites for chlorine adsorption on Si(111) — •J. I. Flege1, Th. Schmidt2, J. Falta2, G. Materlik1,3, M. Çakmak4, and G. P. Srivastava51HASYLAB at DESY, Notkestr. 85, D-22603 Hamburg — 2Inst. f. Festkörperphysik, Universität Bremen, Postfach 330440, D-28334 Bremen — 3Rutherford Appleton Laboratory, Chilton, Oxfordshire OX11 0QX, UK — 4G. U. Fen-Edb. Fak. Fizik Bölümü, 06500 Teknikokullar, Ankara, Turkey — 5School of Physics, University of Exeter, Stocker Road, Exeter EX4 4QL, UK

The investigation of dry and assisted chemical etching for the halogen-silicon system has attracted much interest in the last decade. In this study it is shown for the adsorbate system Cl/Si(111)-(1×1) that the combination of the x-ray standing waves (XSW) method with x-ray photon stimulated desorption (XPSD) and x-ray photoelectron spectroscopy (XPS) allows the quantitative determination of defect sites. On one hand, the on-top majority adsorption site could be determined with Cl 1s photoelectrons as the secondary signal, while on the other hand, minority sites could be selectively investigated due to their much more favorable desorption cross section in XPSD. These desorption-active defect sites could be identified as chlorine atoms chemisorbed at {1 1 2}-like step edges. Furthermore, results of scanning tunneling microscopy (STM) measurements which provide insight into the etching process are presented. Additionally, structural models for the relaxed step-edge geometry obtained by ab initio density functional theory (DFT) calculations are discussed and compared to the experimental results.

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