Dresden 2011 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 60: Poster Session IV (Solid/liquid interfaces; Semiconductors; Oxides and insulators; Graphene; Plasmonics and nanooptics; Electronic Structure; Surface chemical reactions; Heterogeneous catalysis)

O 60.10: Poster

Mittwoch, 16. März 2011, 17:30–21:00, P4

Different bandstructures of for- and backward buckled π-bonded chains of the Si(111)-2×1 surface reconstruction revealed by STS-measurements — •Karolin Löser, Martin Wenderoth, Thomas K. A. Spaeth, and Rainer G. Ulbrich — IV. Physikalisches Institut, Georg-August Univ. Göttingen, Germany

According to the Pandey model, the π-bonded chains of the Si(111)-2×1 surface reconstruction might be buckled either for- or backward but it is extremely hard to distinguish the buckling types as the energetic difference is very small [1] and the projection of the atomic positions is exactly the same seen from above the surface. Because of this, STM cannot be used to determine the buckling type directly.

To gain access to information on the buckling type we exploit the boundaries between domains of differently reconstructed π-bonded chains as a tool to reveal displacements of the chains. Thus, with high-resolution STM and STS measurements of π-bonded chains on cleaved Si(111)-2×1 samples in the UHV, we can not only proof the co-existence of for- and backward buckled π-bonded chains but also study the local Density of States (LDOS) of differently buckled π-bonded chains. We find that two different LDOSs for the two buckling types, one of them has a smaller bandgap than the other, which fits well with calculations [2] that predict the backward buckled π-bonded chains to have a slightly smaller bandgap. We acknowledge financial support by the DFG via project WE 1889/3.

[1] A. A. Stekolnikov, et al. Phys. Rev. B 65 (11), 115318 (2002)

[2] S. H. Lee and M. H. Kang. Phys. Rev. B 54 (3), 1482(1996)