Abstract
Motivated by diffraction experiments on the (2√3 x √3) R30◦ reconstructed Si(111) surface due to deposition of rare earth elements (Dy, Tb) and silicide formation, we analyse the splitting and non-splitting of superstructure diffraction spots. For this purpose, we model diffraction patterns for one-dimensional structures generated by the binary surface technique and use supercell models to keep the analysis simple. Diffraction patterns are calculated in the framework of the kinematical diffraction theory, and they are analyzed as a function of the domains and domain boundaries. Basic properties of the diffraction pattern are analyzed for model systems of a two-fold and a three-fold periodicity. The rules derived from these calculations are applied to the “real-world” system of Si(111)-(2√3 × √3) R30◦-RESix (RE = Dy or Tb). Depending on the combination of domains and domain boundaries of different types, a plethora of different features are observed in the diffraction patterns. These are analyzed to determine the sizes of both domain boundaries and domains from experimentally observed splitting of specific superstructure spots.
Highlights
IntroductionSuperstructures are often formed after deposition of adlayers in the submonolayer regime or even beyond
Many surfaces exhibit superstructures formed to minimize their surface energy
We model diffraction patterns for one-dimensional structures generated by the binary surface technique and use supercell models to keep the analysis simple
Summary
Superstructures are often formed after deposition of adlayers in the submonolayer regime or even beyond These superstructures often show defects as point defects, e.g., vacancies, or line defects, e.g., domain boundaries. It has been demonstrated that the distribution of defects can be obtained from spot profile analysis (SPA-LEED) in order to learn about the morphology of surfaces [4,5,6,7]. This analysis is performed by applying diffraction theory in the kinematic approximation. We apply our results to analyze the complex structure of 2 3 × 3 R30◦ reconstructed Si(111) surface due to rare earth silicide formation where several layers are involved in the formation of the superstructure [11]
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