Berlin 2015 – scientific programme

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DS: Fachverband Dünne Schichten

DS 36: Poster Session I

DS 36.71: Poster

Thursday, March 19, 2015, 09:30–12:00, Poster A

Stable phases of Si(111)-(5×2)-Au surface: Dependence on Au and Si adatom coverages — •Kaori Seino and Friedhelm Bechstedt — Institut für Festkörpertheorie und -optik, Friedrich-Schiller-Universität Jena, Jena, Germany

Over a few decades, the Si(111)-(5×2)-Au surface has been attracted wide interest in experimental and theoretical studies, because it belongs to the family of Si surfaces on which metal-induced atomic nanowires appear. The experimental determination of the Au coverage has been revised to be 0.6 monolayer (ML) instead of 0.4 ML. Correspondingly, several structural models have been proposed and discussed [1]. However, recently a model with seven Au atoms per (5×2) cell was proposed by using density functional theory calculations [2].

Si adatoms are observed on the Si(111)-(5×2)-Au surface by STM. The effect for their stability was discussed using first-principles calculations with contradictory results [1-3]. The adatom stability of the model with 7 Au atoms decreases with the density of Si adatoms [2], although the surface energy is lowest for the Si-adatom coverage of 1/4 ML per (5×1) cell for the model with 0.6 ML [3]. Here we present ab-initio calculations of Si(111)-(5×2)-Au in order to identify stable phases and their variation with Au coverage and Si adatom decoration.

[1] K. Seino and F. Bechstedt, Phys. Rev. B 90, 165407 (2014).

[2] S. G. Kwon and M. H. Kang, Phys. Rev. Lett. 113, 086101 (2014).

[3] S. C. Erwin et al., Phys. Rev. B 80, 155409 (2009).