Size-dependent plasmon effects in periodic W-Si- based mirrors, investigated by X-ray photoelectron spectroscopy

Thickness-dependent shift of energy position and fine structure of the collective oscillation of electron gas (plasmons) in the upper layer of silicon (Si) and tungsten (W) in the W/Si and Si/W multilayer mirrors was studied by X-ray photoelectron spectroscopy, respectively. In the spectra, doublet energy components of plasmon excitation were observed, which belong from the Si/vacuum or W/vacuum, and W/Si or Si/W interfaces. The plasmon excitation energy depended on the thickness of the Si and W layers in the multilayers. The intensity of the plasmon component along with the Si/vacuum or W/vacuum interfaces was increased with increasing the thicknesses of Si (or W). However, the intensity was declined along with the W/Si (or Si/W) interfaces. The fine structure of the plasmon was explained by proposing the framework of the electron scattering model in a thin film with the consideration of a semi-infinite solid. The contribution of surface and volume plasmons excitation to the reflectivity of the multilayer mirrors was described. The reflectivity of mirrors was higher for the lower value of plasmons excitation intensity.

Automated summary

The study investigated the thickness-dependent shift of energy position and fine structure of plasmons in the upper layer of silicon and tungsten in W/Si and Si/W multilayer mirrors using X-ray photoelectron spectroscopy. The results showed that plasmon excitation energy and intensity varied with the thickness of Si and W layers, with different behaviors along different interfaces. The reflection intensity of the mirrors was found to be higher for lower values of plasmons excitation intensity.