Absorption of light by ultra-thin silicon films covered with a monolayer of elliptical metal nanoparticles

•Optical properties of system of metalic nanoparticles on ultra-thin Si film are studied theoretically.•The effective susceptibility concept is applied to study effects in such hybrid systems.•By changing the configuration of system the formation of a collective plasmon-waveguide is shown. The absorption of Si films covered with an array of elliptical metal nanoparticles (NPs) of identical orientation and shape is investigated theoretically. We consider silicon films with thickness in the range of 80–200 nm. The symmetry axis of the NPs is taken perpendicular to the surface of silicon surface and their short axis has a radius of 10 nm in the plane of the Si film. A 10-nm-thick SiO2 layer separates the submonolayer NP coverage from the silicon film. The spectral properties of the considered hybrid system are studied in terms of its effective susceptibility. Specifically, the dependence of light absorption by the NPs covering the ultrathin Si film on their morphology and material composition is established. For chromium and silver NPs, the appearance of collective absorption modes in the hybrid structures is predicted.