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Various techniques have been developed for computing electronic surface band structures of three-dimensional semiconductors. They use either the local-density functional approximation and first-principle pseudopotentials or an (s, p, s*) set of tight-binding parameters1. Such theoretical calculations, as detailed and realistic they may be, are nevertheless individual case studies. Here, more conceptual approaches shall be considered. A linear, one-dimensional lattice will be treated by using both the nearly free electron and a tight-binding approximation. First, however, the complex band structure of semiconductors will be considered. Adatoms on semiconductor surfaces are forming chemical bonds with substrate atoms. Sparsely distributed adatoms will predominantly interact only with their nearest neighbors. Then adatom-substrate bonds may be treated in analogy to isolated, heteropolar molecules. The energy levels of such surface-molecules will be obtained by using a simple tight-binding approach. Covalent bonds are partly ionic. Therefore, adatoms will induce surface dipoles in addition to surface states. As with small molecules, the chemical trends of the adatom-induced surface dipoles may be predicted from the difference of the adatom and substrate electronegativities.
KeywordsSemiconductor Surface Dangling Bond Surface Dipole Free Electron Model Occupied Surface State
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- 1.The theoretical methods used in calculating electronic properties of semiconductor surfaces are described in reviews by Forstmann  and Pollmann  and in a monograph by Lannoo and Friedel .Google Scholar
- 2.See textbooks on solid state physics, for example, the one by Ibach and Lüth .Google Scholar
- 3.See Table 3.1 and a compilation by Jaros .Google Scholar
- 4.See, for example, Burns .Google Scholar
- 5.See Table 3.1 and a compilation by Jaros .Google Scholar
- 6.See textbooks on solid state physics as, for example, the one by Ibach and Lüth .Google Scholar
- 7.See, for example, the monograph by Harrison .Google Scholar
- 8.Parr et al.  have established a connection between electronegativity and quantum mechanics. The present state of the art in this field has been reviewed by Sen and Jorgenson . It was concluded that ‘electronegativity, perhaps the most popular intuitive concept in chemistry, can now be treated as a quantum chemical parameter’.Google Scholar