Investigation of dielectric functions of a layer of Ag nanoparticles on silicon using spectro-ellipsometry and spectrophotometry

An investigation of the optical characteristics of a layer of Ag nanoparticles deposited from an AgNO$_3$ solution on the surface of single-crystal Si is presented. The measurements were carried out using spectroscopic ellipsometry and spectrophotometry at the same tilt angle and sample probe location in a wide spectral range from 200 to 1700 nm. From the obtained experimental data, the parameters of the Drude–Lorentz model and the complex dielectric function were determined, which was compared with the pseudo-dielectric function. Both dependences revealed resonances of a bulk plasmon near the energy $E$ = 3.8 eV, while a localized plasmon was detected in the pseudo-dielectric function at $E$ = 1.65 eV, and in the dielectric function at $E$ = 1.84 eV.