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Ge-substitutional defects and the r3xr3 <--> 3x3 transition in alpha--SnGe(111)

Jose Ortega·Ruben Perez·Leszek Jurczyszyn·Fernando Flores
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Abstract

The structure and energetics of Ge substitutional defects on the alpha-Sn/Ge(111) surface are analyzed using Density Functional Theory (DFT) molecular dynamics (MD) simulations. An isolated Ge defect induces a very local distortion of the 3x3 reconstruction, confined to a significant downwards displacement (-0.31 A) at the defect site and a modest upward displacement (0.05 A) of the three Sn nearest neighbours with partially occupied dangling bonds. Dynamical fluctuations between the two degenerate ground states yield the six-fold symmetry observed around a defect in the experiments at room temperature. Defect-defect interactions are controlled by the energetics of the deformation of the 3x3 structure: They are negligible for defects on the honeycomb lattice and quite large for a third defect on the hexagonal lattice, explaining the low temperature defect ordering.

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Jose Ortega, Ruben Perez, Leszek Jurczyszyn, Fernando Flores. 2001-07-05. Ge-substitutional defects and the r3xr3 <--> 3x3 transition in alpha--SnGe(111). https://doi.org/10.1088/0953-8984%2F14%2F30%2F305

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