Si overgrowth on Si(111)root 3x root 3-B surface phase

Si(111)root 3 X root 3-B surface phase has been formed by high-temperature annealing of B-doped Si samples. Low-energy electron diffraction observations have revealed that the Si(111)root 3 X root 3-B surface phase is very stable with respect to heating and that the root 3 X root 3 reconstruction is still detected at temperature as high as 950 degrees C. Scanning tunnelling microscopy has been used to study the growth of Si on Si(111)root 3 x root 3-B surface. At low temperatures (20-300 degrees C) the growth has been found to be affected greatly by surface defects which trap Si atoms and act as sites of preferential island nucleation. At temperatures of Si(111) epitaxy (greater than or equal to 400 degrees C) Si islands grow amorphous up to a certain critical size and then ''crystallize'' to form epitaxial islands with a thickness of two Si(111) bilayers. The structure on top of epitaxial Si islands is always root 3 X root 3 which suggests boron segregation to the surface.