SCANNING-TUNNELING-MICROSCOPY STUDY OF SI GROWTH ON A SI(111)ROOT-3X-ROOT-3-B SURFACE

Scanning tunneling microscopy is used to study the growth of Si on a S i(111) root 3x root 3-B surface at Si coverages from submonolayer rang e up to a few monolayers and in an temperature range from 20 to 600 de grees C. Already at room temperature the deposited Si atoms are very m obile on the Si(111) root 3x root 3-B surface. As a result, the amorph ous Si islands are formed, leaving the root 3x root 3 reconstruction b etween islands intact. The dangling bond ''bright'' adatoms of the Si( 111) root 3x root 3-B surface were found to be preferential sites for island nucleation. At temperatures of Si(111) epitaxy (greater than or equal to 400 degrees C) Si islands grow amorphously up to a certain c ritical size and then ''crystallize'' to form epitaxial islands. The s tructure on top of epitaxial Si islands is always root 3x root 3, whic h suggests B segregation to the surface. The island shape (random belo w 600 degrees C) is considered to be governed by the structure and pro perties of the Si(111) root 3x root 3-B surface.