STM/STS Studies of Self-Organized Growth of Iron Silicide Nanocrystals on Vicinal Si(111) Surface

The evolution of iron silicide structure grown by solid state epitaxy on Si(111) vicinal surface was investigated by scanning tunnelling microscopy. The reactions, which occur on the surface, are compared for two various Fe coverages: 0.33 and 2 monolayers. The annealing at 250˚C does not enable substantial recovery of the surface ordering, deteriorated by Fe deposition at room temperature. The onset of 2×2 surface reconstruction is observed upon annealing at 400˚C. A three-dimensional growth tendency of iron silicide crystallites on a bare Si(111) 7×7 surface was found at 700˚C. In the case of 2 monolayer coverage crystallites nucleate along the edges of substrate terraces forming a regular array of nanometer size dots. Basing on atomically resolved spectroscopic effects and statistical considerations, structure of iron silicide nanocrystallites as well as Schottky-like character of the barrier at the interface between metallic crystallite and semiconducting substrate is deduced.