Modification of the scattering of silver nanoparticles induced by Fabry–Pérot resonances rising from a finite Si layer

In this paper we theoretically give evidence of the enhancement of scattering phenomena related to single metal nanoparticles having different shapes and located on a silicon layer having finite thickness, thus resembling a thin film solar cell. The study has been carried out in order to deeply understand how the presence of corners (nanobrick) or rounded edges (nanosphere) and the contact surfaces between the metal nanoparticle and the semiconductor affect the scattering when a finite Si layer is considered right below the nanoparticles. Arrays of such silver nanoparticles have also been investigated through a proprietary finite-difference time-domain-based code. The comparison with a typical configuration, where the semiconductor layer is semi-infinite, leads us to note that, in dependence on the shape and size of the nanoparticles, the finite layer, which acts as a Fabry-Perot resonant cavity, is able to exceptionally twist the forward and backward scattering. In particular the forward scattering in all cases is enhanced, whereas the backward scattering seems to be more sensitive to the interference induced by resonances rising in the finite dielectric layers, since it exhibits opposite effects depending on the nanoparticle shapes.