Scanning tunneling microscopy observation of the formation of the smallestdimer-adatom-stacking-fault domain on a quenched Si(111) surface

We have observed the formation of the Dimer-Adatom-Stacking-fault (DAS) dom ain in unreconstructed regions on quenched Si(111) surfaces by scanning tun neling microscopy at 370-380 degrees C. It is observed that a single faulte d (F)-half of the unit cell of the DAS structure is coated from a corner ho le of existing odd-sized F-halves at the edge of the DAS domain. It is demo nstrated that the formation of the F-half in the domain growth follows the sequential size-change (SSC) model, which was proposed earlier as the forma tion mechanism of single isolated F-halves, The smallest DAS domain consist s of three F-halves of the same size, arranged as a triangle. We have summa rized the characteristic steps of the formation towards the smallest domain under the SSC model.