Electronic properties of Si(111)-7×7 and related reconstructions: Density functional theory calculations

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DOIResolve DOI: http://doi.org/10.1103/PhysRevB.85.195315
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TypeArticle
Journal titlePhysical Review B - Condensed Matter and Materials Physics
ISSN1098-0121
Volume85
Issue19
Article number195315
AbstractThe 7×7 reconstruction of Si(111) has the interesting property of being metallic despite bulk Si being a semiconductor. This surface has a complex reconstruction that takes on a dimer-adatom stacking fault (DAS) structure composed of adatoms, rest atoms, and several other key features. It is believed that the dangling bonds of the adatoms play a crucial role in the high conductivity and that this is predominantly a surface-state band effect. To elucidate the details of this mechanism, we investigate a set of related Si(111) reconstructions of increasing complexity in order to resolve the effect of the different DAS features on the electronic and transport properties of the Si(111)-7×7 surface. Density functional theory calculations are carried out on the √3×√3-R30 -, 2×2, 5×5, and 7×7 reconstructions of Si(111). Since these surfaces are modeled as two-dimensional slabs, a careful investigation is carried out to determine the slab thickness needed to capture the structural and electronic properties of these systems. The densities of states (DOSs) projected on different atoms in these surfaces are then compared, revealing that the √3×√3, 5×5, and 7×7 surfaces are metallic, while the 2×2 surface is semiconducting. Finally, the DOSs for Si(111)-7×7 are related to scanning tunneling microscope data to offer an explanation for different adatom prominence trends depending on Si sample doping. © 2012 American Physical Society.
Publication date
LanguageEnglish
AffiliationNational Research Council Canada (NRC-CNRC); National Institute for Nanotechnology (NINT-INNT)
Peer reviewedYes
NPARC number21269255
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Record identifierea758e3f-822c-4d65-91f8-7bd9b5cd360f
Record created2013-12-12
Record modified2016-05-09
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