FORMATION OF THE MG-SI(111) INTERFACE STUDIED BY SURFACE EXAFS

Interface formation between Mg and Si(111) was investigated by polarization-dependent Mg{single bond}K surface EXAFS (SEXAFS). At room temperature, a (√3 × √3)R 30° superstructure is formed for a coverage of 1/3 ML. It results from the periodic arrangement of Mg atoms on four-fold atop sites (T4). Further Mg deposition preserves the (√3 × √3)R30° LEED pattern up to1 ML, and the SEXAFS data indicate the adsorption of the additional Mg atoms on off-centered T-sites. A progressive occupation of such T-sites beyond the 1 ML coverage leads then towards bulk-like local ordering. © 1990 Pergamon Press plc.