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p ( 1 × 1 ) to c ( 4 × 8 ) periodicity change in ultrathin iron silicide on<mml:math xmlns:mml="http://www.w3.org/1998…

2003; American Physical Society; Volume: 68; Issue: 3 Linguagem: Inglês

10.1103/physrevb.68.033302

1095-3795

S. Hajjar, G. Garreau, S. Pelletier, D. Bolmont, C. Pirri,

Advanced Materials Characterization Techniques

Iron silicide layers grown by solid phase epitaxy on Si(111) are investigated using scanning tunnel microscope (STM), low-energy electron diffraction and low-energy ion spectroscopy. These layers, which are flat and homogeneous for a selected Fe thickness range, exhibit a $p(2\ifmmode\times\else\texttimes\fi{}2)$ surface superstructure whatever the annealing temperature above 600 K. Voltage-dependent STM images reveal a modification of the silicide symmetry, from a $p(1\ifmmode\times\else\texttimes\fi{}1)$ towards a $c(4\ifmmode\times\else\texttimes\fi{}8)$ in-plane periodicity, above 800 K. This transition is associated with an organization of chemical species under two Si atomic planes.