UHV transmission electron microscopy structure determination of the Si(111)-(√3 × √3)R30°Au surface

Richard Plass*, Laurence D. Marks

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

26 Scopus citations

Abstract

Details of the average atomic structure and the possible nature of the surface domain walls of the Si(111)-√3 × √3)R30°Au surfaces are presented. Transmission electron diffraction data supports the missing top layer twisted trimer [Surf. Sci. 256 (1991) 135] model in which gold and silicon atoms in the top two layers form sets of like-atom trimers rotated in the same direction about p3 symmetry centers. However, the average degree of trimer rotation and the interatomic spacings within the structure vary significantly with the sharpness of the structure's diffraction spots. These variations in structure parameters among data sets as well as large values of the fitted Debye-Waller terms indicate substantial static disorder in the structure and hence any parameters determined can only be averages of locally varying parameters. Silicon displacements from the bulk positions continue through the second silicon double layer. Charge transfer in the structure is evident from a better fit obtained using Au+ scattering factors than with those for neutral gold, confirming a total energy cluster calculation [Surf. Rev. Lett. 1 (1994) 273]. The presence of gold trimers is confirmed by the local symmetry seen in high resolution micrographs which also show surface domain morphology differences between diffuse and sharp diffraction spot regions. These images additionally indicate that the surface domain walls must be either vacancy type, or the gold-to-gold spacing in and near the walls must be close to 3.84 Å. From these observations, models for the Si(111)-(√3 × √3)R30°Au domain walls and the Si(111)-(6 × 6) Au structure are proposed.

Original languageEnglish (US)
Pages (from-to)233-249
Number of pages17
JournalSurface Science
Volume342
Issue number1-3
DOIs
StatePublished - Nov 20 1995

Keywords

  • Computer simulations
  • Gold
  • Low index single crystal surfaces
  • Semiconducting surfaces
  • Si(111)-(√3 × √3) R30°Au
  • Silicon
  • Surface defects
  • Surface structure
  • Transmission electron microscopy
  • Transmission high-energy electron diffraction

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Materials Chemistry

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