STM and SEM studies on the character of triangular Si(111)-7 × 7 domains formed in quenched Si(111) surface

STM and SEM observations have been made on the 7 × 7 ordering process of quenched Si(111)-1 × 1 surface and on quenched metastable atom complexes. All the triangular 7 × 7 domains nucleated in the 1 × 1 region have been found to have character 〈112〉. The rate-controlling process for the growth is the nucleation of a faulted half cell at the outermost edge of the triangular domain. Corner holes, instead of dimer rows play a critical role for the nucleation of the faulted half cell. The contrast of STM filled state images have been examined on the quenched complexes; it is dark for the centered adatoms of 9 × 9 and 11 × 11, and for all the adatoms of 2 × 2, c(2 × 4) and a defected half of unfaulted type which was found for the first time in the present work. In contrast with these complexes, the adatoms of √3 × √3 structure appear bright. These features are interpreted in terms of the charge transfer (between the adatoms and rest atoms) mechanism. Extreme stability has been noted for a triangular defect region of 1 × 1 (with side a ) in quenched Si(111) and has been attributed to the domain boundaries running from the apices of the triangular defect. The stability has been analysed quantitatively in terms of the energy versus a curve derived in this paper.