Abstract
Two-dimensional rare-earth silicide layers deposited on silicon substrates have been intensively investigated in the last decade, as they can be exploited both as Ohmic contacts or as photodetectors, depending on the substrate doping. In this study, we characterize rare-earth silicide layers on the Si(111) surface by a spectroscopic analysis. In detail, we combine Raman and reflectance anisotropy spectroscopy (RAS) with first-principles calculations in the framework of the density functional theory. RAS suggests a weakly isotropic surface, and Raman spectroscopy reveals the presence of surface localized phonons. Atomistic calculations allow to assign the detected Raman peaks to phonon modes localized at the silicide layer. The good agreement between the calculations and the measurements provides a strong argument for the employed structural model.
Highlights
The spectra are fitted with Voigt profiles with a fixed Gauss width equal to the spectral resolution of 3.5 cm−1
The Raman signatures measured for terbium silicide layers grown on 4◦ -offcut Si(111)
Surfaces can be understood on the basis of the phonon modes calculated for the stoichiometric silicide monolayer of (1 × 1) periodicity grown on the Si(111) substrate
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Rare earth (RE) deposition on Si substrates followed by thermal annealing leads to the formation of various structures consisting of rare-earth silicides of different composition. The amount of deposited rare earths, the substrate orientation, and the annealing process can be exploited to obtain structures of different dimensionality (from one dimensional (1D) to three-dimensional (3D)), periodicity, and morphology
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