Surface morphology and reconstructions of ultra thin Si films grown by solid-phase epitaxy

Solid-phase epitaxy has been performed on Si(100) and Si(111) surfaces at substrate temperatures in the range of 350-650 degrees C and for film thickness up to a few monolayers. The features of the epitaxial films were acquired by scanning tunnelling microscopy. Each surface displays a complete epitaxial layer consisting of characteristic domains and islands on top of the epitaxial layer. On the Si(100) surface all the domain boundaries in the direction of dimer rows manifest themselves as surface depressions while those ones perpendicular to the dimer rows are decorated by islands. At an epitaxial temperature of about 600 degrees C a metastable Si(100)c(4 x 4) reconstruction can form. On the Si(111) surface the complete epitaxial layer consists of [110]-shaped net-like domains and have islands at the net knots. At epitaxial temperatures between 400 degrees C and 600 degrees C 5 x 5, 9 x 9, 11 x 11, c(4 x 2) and root 3 x root 3 structures can be prepared. If the film thickness exceeds two bilayers, degeneration of the dimer-adatom-scacking-fault (DAS) structure to related 2 x 2 and c(4 x 2) can be observed at temperatures between 400 degrees C and 500 degrees C. (C) 1997 Elsevier Science S.A.