Scanning tunneling microscopy of the7×7to3×1transformation induced on the Si(111) surface by Na adsorption

Absolute coverage determination in the K/Si(111):B-23×23R30∘surface

“…These islands appear brighter than the 7 × 7 domain; this is not due to a second K layer stacked but to a complex Si mass redistribution during the destruction of the 7 × 7 DAS structure. 9 Ultimately, on both 3 × 1 terraces and islands, the K coverage has the same 1/3 ML value. The closest view (60 × 60 nm 2 , same tunneling parameters), shows the boundary between 7 × 7 and 3 × 3 (terrace and islands) domains.…”

“…2). A comprehensive study of growth mechanisms has been carried out by Saranin et al 9 in the case of Na/Si(111)-3 × 1. We report here similar observations concerning K which, to the best of our knowledge, have not been documented in the literature.…”

“…3,4 Upon deposition of monovalent adsorbates (alkali and Ag atoms), for instance, the 7 × 7 reconstruction is destroyed at the benefit of the three-domain, one-dimensional 3 × 1 reconstruction. [5][6][7][8][9] Basically, such a reconstruction is triggered because electrons provided by the adsorbates can, in addition to dangling electrons of the clean surface, lead to completely filled bands, which lower the electronic energy. The widely accepted atomic structure relies on the honeycomb chainchannel (HCC) model, 11 in which each unit cell contains one alkali atom, so that the coverage is 1/3 of a monolayer (ML) with respect to the 1 × 1 undistorded unit cell.…”

Self-assembled lead atomic nanowires on pre-structured Sm/Si(111) interfaces

“…The surfaces are formed by the both (3 · 2) and (7 · 1) structures which appear as adsorbatechains induced by the adsorption of Sm atoms on Si(1 1 1) [18][19][20]. Their structure models are based on an appropriate combination of honeycomb chain channel (HCC) and Seiwatz Si chains [18,[21][22][23][24][25][26][27][28]. In our study, lead (Pb) atoms are evaporated on these pre-structured surfaces.…”

Restructuring of the Ge(100) surface by Na chains

“…[2][3][4][5] Adsorption induced reduction of symmetry, on the other hand, is a general phenomenon seen as formation of various adsorbate induced superstructures. The peculiarity of metal adsorption, e.g., on Si͑111͒ [6][7][8] and for adsorption of sodium on Si͑100͒ 9,10 is the formation of chain structures, which have in part remarkably large periodicities between the chains. The coupling mechanism has been clarified only in some cases.…”