Si(111)-7 × 7 and Ge(111)-c(2 × 8) Surfaces

  • Winfried Mönch
Part of the Springer Series in Surface Sciences book series (SSSUR, volume 26)


In addition to the 2 × 1 reconstruction, which is observed after cleavage, silicon and germanium {111} surfaces possess 7×7 and c(2 × 8) reconstructions, respectively, after annealing treatments at elevated temperatures. The common feature of these large-unit-mesh reconstructions is the reduction of the number of dangling bonds per surface unit area by a factor of 2.6 and 2, respectively. The correlated lowering of the total energy is achieved by adatoms, each of which saturates three dangling bonds while it possesses one only. Such adatoms are naturally introducing surface strain. In c(2 × 8)-reconstructed Ge(111) surfaces, the related elastic energy is obviously overcompensated by the lowering of the band-structure energy due to the reduction of the density of dangling bonds. The 7×7 reconstruction, on the other hand, needs an additional decrease of the density of dangling bonds which is accomplished by the existence of surface dimers. Their formation needs the introduction of a stacking fault in half of the 7 × 7 unit mesh and the generation of a corner hole.


Scanning Tunneling Microscopy Scanning Tunneling Microscopy Image Dangling Bond Scanning Tunneling Spectroscopy Unit Mesh 
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  1. 1.
    Stacking-fault energies may be deduced from electron-microscopic images of dislocations which dissociate into two partial dislocations with a stacking fault in between. Experimental data for silicon have been compiled by Chou et al. [1985].Google Scholar

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© Springer-Verlag Berlin Heidelberg 1995

Authors and Affiliations

  • Winfried Mönch
    • 1
  1. 1.Laboratorium für FestkörperphysikGerhard-Mercator-Universität DuisburgDuisburgGermany

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