Spectroscopic Analysis of Rare-Earth Silicide Structures on the Si(111) Surface

• Published in: Materials Vol. 14; no. 15; p. 4104
• Main Authors: Sanna, Simone, Plaickner, Julian, Holtgrewe, Kris, Wettig, Vincent M., Speiser, Eugen, Chandola, Sandhya, Esser, Norbert
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 23.07.2021; MDPI
• Subjects: Agreements; Anisotropy; Annealing; Contact resistance; Density functional theory; First principles; Intermetallic compounds; Morphology; Phonons; Raman spectroscopy; Rare earth elements; rare earth silicide; RAS; Reflectance anisotropy spectroscopy; Silicides; Silicon substrates; Spectroscopic analysis; Spectrum analysis; Structural models; surface science; terbium silicide
• ISSN: 1996-1944; 1996-1944
• DOI: 10.3390/ma14154104

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.