Regensburg 2019 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 18: Poster Monday: Nanostructures

O 18.3: Poster

Montag, 1. April 2019, 17:45–20:00, Poster F

First-principles investigation of the vibrational properties of rare-earth silicides on the Si(111) surface — •Vincent Maximilian Wettig, Kris Holtgrewe, Christof Dues, and Simone Sanna — Justus-Liebig-Universität Gießen, Gießen, Hessen

The investigation of the vibrational properties has recently become one of the most appealing tools for surface analysis. As Raman frequencies and selection rules are strongly related to the surface structure, they represent reliable criteria to identify, validate or rule out competing structural models [1].

In this work, we model from first principles the vibrational properties of rare-earth silicide monolayer structures deposited on Si(111) surfaces. As the resulting metal/semiconductor interface is characterized by an extraordinarily low Schottky-barrier height (0.3*0.4 eV on n-type substrates), the silicide nanostructures are both of technological and academic interest.

Employing previously proposed structural models based on the hexagonal DySi2 lattice [2], we demonstrate the existence of surface localized phonon modes of different symmetry in the frequency range between 25 and 500 cm-1 for the investigated dysprosium and terbium silicides. The rare earth atom has a minor influence on the calculated frequencies, which is attributed to the atomic mass difference.

[1] B. Halbig et al., Phys. Rev. B 97, 035412 (2018)

[2] S. Sanna et al., Phys. Rev. B 93, 195407 (2016)