Effect of Mie resonances in coatings consisting of dielectric particles on the light propagation in substrate surface layers

Abstract

The principal advantage of antireflection coatings consisting of subwavelength dielectric particle arrays is their ability to change the propagation direction of incident electromagnetic radiation and direct it along substrate surface layers. We have studied coatings consisting of Ge disk lattices on a glass substrate coated with an ITO film. The addition of Ge disks reduces the reflection in the wavelength region of the dipole and quadrupole resonances excited in the disks, compared to the ITO film reflection alone. Ge disk lattices also provide a much stronger absorption, compared to a Ge coating of the same thickness as the height of the disks. The presence of a peak in the absorption spectra and its dependence on the lattice period indicates that scattered radiation participates in the collective lattice resonance and is directed along the substrate surface. Such property of dielectric particle coatings can increase the efficiency of photoelectric devices, such as solar cells and photodetectors.