Hybrid gold nanoantenna array—Dielectric thin film anti-reflection coatings on GaAs

We present broadband reflectivity spectra of a gold nanoantenna array-silicon dioxide thin film on GaAs. We show that the inclusion of the gold nanoantenna array significantly reduces the reflectivity compared with the thin dielectric film only on GaAs when an appropriate nanoantenna geometry is chosen. Our measurements reveal a highly asymmetric line-shape of the reflectivity spectra close to the nanoantenna localised surface plasmon wavelength due to an interference effect between incident and scattered light. Using detailed scattering matrix simulations we also demonstrate that the reflectivity can be further reduced over the considered wavelength range (350–1200 nm) using this approach. Our results are important for the optimised design of nanoplasmonic-dielectric structures for enhancing in-coupling of light into semiconductor (GaAs, silicon etc) solar cells.

► Reflectivity spectra of gold nanoantenna array on SiO2 thin film on GaAs substrate.
► Reflectivity line-shape highly asymmetric and explained by interference effect.
► Reflectivity is reduced compared to SiO2 thin film on a GaAs substrate only.
► Simulation: reflectivity can be further reduced over wavelengths of 350–1200 nm.
► Results important for design of nanoplasmonic-dielectric anti-reflector for PV.