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

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.

Surface Atomic Arrangement of Aluminum Ultra-Thin Layers Grown on Si(111)

“…Figure 2 a shows the RHEED pattern of the Al films grown on the Si(111)-7 × 7 surface. The image was captured in the [ 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 ] azimuth direction after 2 h of annealing. The specular beam intensity indicated by spots A and B identifies the Si(111)-1 × 1 lattice originating from the bulk.…”

“…Knowing the details of the surface structure and its crystalline arrangement is critical for the deposition of ultrathin metallic films, especially if protection against atmospheric oxidation is required. The metallic surface is harmed by atmospheric exposure, which causes partial amorphization and severely limits its functionality [ 6 , 7 , 8 , 9 , 10 , 11 , 12 ]. This affects surface electrical conductivity and controls the current efficiency in many applications [ 12 , 13 , 14 ].…”

Interplay between magnetic order and electronic band structure in ultrathin GdGe2 metalloxene films

“…1(a)) corresponds to the one reported previously in the literature. 23,26,43 It consists of a single layer of Gd atoms sandwiched between the Ge(111) substrate and the buckled Ge surface bilayer (BL). This BL displays a reversed buckling with respect to the substrate.…”

Unveiling the stacking-dependent electronic properties of the 2D ultrathin rare-earth metalloxenes family LnX2 (Ln = Eu, Gd, Dy; X = Ge, Si)

“…14 The electronic band structures of some LnX 2 films were investigated through angle resolved photoemission spectroscopy (ARPES) [15][16][17][18][19][20] and density functional theory (DFT) studies. 10,20,21 However, a systematic study treating the electronic properties of these films as a function of thickness, Ln and host X element is still missing. The electronic and magnetic properties of LnX 2 films are furthermore expected to be sensitive to external perturbations, such as strain, charge doping and electric field.…”

“…Indeed, these systems demonstrated fingerprints of strong 2D ferromagnetic (FM) ordering in the monolayer (ML) limit, 11 together with high carrier mobility, 12 non-trivial topology 13 and remarkable transport phenomena. 14 The electronic band structures of some LnX 2 films were investigated through angle resolved photoemission spectroscopy (ARPES) [15][16][17][18][19][20] and density functional theory (DFT) studies. 10,20,21 However, a systematic study treating the electronic properties of these films as a function of thickness, Ln and host X element is still missing.…”