Fig. 1. (Color online) (a) AFM image of ultrathin PLD grown WS₂ 5 ML/Al₂O₃ film. AFM image size 800 nm × 800 nm × 1 nm. The surface roughness (RMS) is estimated as 0.2 nm. Height profile drawn along the horizontal red line is shown below the AFM image. (b) X-ray absorption (fluorescence yield) and X-ray reflectance (at 2° of incidence) spectra measured across W L₃ absorption edge in Ag/WS₂/Al₂O₃ multilayer.

Fig. 2. (Color online) X-ray reflectivity curves measured (black) and modeled (red) at non-resonant photon energy of E = 8051 eV (λ = 1.54 Å) for WS₂/Al₂O₃ epitaxial films with as-designed thickness of 2 (a), (b) and 5 (c), (d) monolayers. The corresponding SLD profiles are shown in panels (b), (d) and are interpreted as transition layer, WS₂ main layer, and W oxide top layer.

Fig. 3. (Color online) Resonant reflectance in Ag/WS₂/Al₂O₃ multilayer. Experimental (a) and modeled (b) maps in the energy range corresponding to the W L₃ absorption edge. Vertical cuts (reflectance curves) of experimental and modeled maps plotted for a few discrete energy values in the vicinity of W L₃ edge (c). The curves are stacked along the y-axis for a clearer visualization.

Fig. 4. (Color online) The real and imaginary parts of SLD across the W L₃ edge obtained by fitting for the Ag/WS₂/Al₂O₃ heterostructure plotted in the form of a depth-energy map (a), as a function of depth at constant photon energy of 10 203 eV (b) and for each layer material (c).