Study of the Optical and Plasmon Features in the Reflectance Spectra of the Silver Nanoparticle Layers Deposited from the AgNO3 onto the Silicon Surface

Abstract

The reflectance spectra of Ag layers on a silicon substrate are interpreted using the approach based on the calculation of the reflectance Rcalc spectra of a thin film with variable thickness, which makes it possible to follow the effect of c-Si substrate critical points in the Brillouin zone and the formation of characteristics of bulk Ag at the edge of interband transitions. The calculated Rcalc spectra were compared with the experimental Rexp spectra of the Ag nanoparticle layers with different morphologies measured at the normal and oblique (45°) angle of incidence of light. For a layer consisting of coarser nanoparticles, one can observe a steep dip in the Rexp spectrum, which almost coincides with the edge of the interband transitions in bulk Ag in the UV range, and a broad dip in the Rexp spectrum with a minimum at λ = 382 nm, which demonstrates the maximum absorption of the localized plasmon resonance of Ag nanoparticles. For the samples consisting of finer particles, the dip of the interband transitions in the Rexp spectra is not observed at both angles of incidence, since the deposited Ag nanoparticles did not form a structure with the optical properties of bulk Ag, but the bulk plasmon resonance appeared at λ ~ 335 nm in the longitudinal mode at the oblique angle of incidence.