Scanning tunneling microscopy observations of Ge solid-phase epitaxy on Si(111)

Solid-phase epitaxy (SPE) of Ge on a clean, 7 × 7-reconstructed Si(111) surface is investigated by scanning tunneling microscopy. Although Ge layers of four monolayers (ML) thick crystallize in the registry of the 7 × 7 reconstruction preserved at the amorphous Ge/Si interface, the 7 × 7 reconstruction hardly influences the SPE of 2 ML thick Ge layers. This difference is due to the reduced movement of atoms at the interface with thicker overlayers.