Phase formation sequence and domain structure: A low-energy-electron-microscopy study of the Si(111)-(√3 × √3 )Ag surface

Changes in nucleation and phase formation sequence with temperature may strongly affect the morphology of the final phase. The Si(111)-({}3 ×{} {}3 )Ag structure develops directly from the clean (7×{}7) structure at lower temperatures (500--700 K). Preferred nucleation at step edges and (7×{}7) domain boundaries reduces the effective dimensionality of the substrate and explains anomalies in domain size scaling observed by Zuo and Wendelken. An intermediate three-domain (3×{}1) structure precedes the {}3 structure at higher temperatures, leading to a complete change in {}3 nucleation and growth, as well as final domain size distribution and total Ag coverage.