Transformations of faulted halves of the DAS structure on quenched Si(111)

We have observed peculiar faulted (F) halves of the dimer-adatom-stacking fault (DAS) structure by scanning tunneling microscopy on quenched Si(111) surfaces at 380 °C, and denoted them irregular F-halves (F′). In the F′-halves, the arrangement of adatoms is partially different from that of corresponding regular F-halves and one adatom is missing. We observed single 5×5-F′, 7×7-F′, 9×9-F′, 11×11-F′ and 13×13-F′ in unreconstructed regions, and proposed their structures. Fluctuations in the size and structure of the faulted halves have been observed in real time by rapid imaging at 380 °C. It is found that single odd-sized faulted-halves appearing in the size changes are always the irregular ones.