Real time dynamics of Si magic clusters mediating phase transformation: Si(111)-(1 × 1) to (7 × 7) reconstruction revisited

► Si(111)-(1 × 1) to (7 × 7) transformation is mediated by Si magic clusters. ► Clusters are mono-disperse (size ~13.5 ± 0.5 Å) and consists of 3 tetra-clusters. ► Clusters formed by heating Si(111) to 1200oC and quenching to room temperature. ► Real time STM shows clusters popping up from (1 × 1) surface during transformation. ► Atomic density difference leads to excess Si atoms forming magic clusters.