Solid-phase epitaxy of thin silicon film on Si(111) surface studied by scanning tunneling microscopy

Solid-phase epitaxy (SPE) of thin silicon film with a thickness of 0.2-2 bilayers (BL) on Si(111)-(7 × 7) surface was studied by scanning tunneling microscopy. At small coverage, the SPE growth proceeds via coarsening of islands. As the coverage exceeds the percolation threshold, a 'mirror' process consisting of coarsening of voids in the continuous layer takes place. The SPE growth of a thicker continuous layer results in a partly disordered flat surface, displaying a mixture of different reconstructions. Quantitative characterization of this surface by the formalism of pair distribution functions reveals an anisotropy in the orientational order that may indicate that SPE occurs preferably in the step direction. A possibility to use an SPE-grown layer as a two-dimensional model for bulk processes in solids is discussed.