2D photonic gratings from thermal imprinting of ITO-based films

Abstract

A nanocomposite system based on titania-bound indium tin oxide (ITO) nanoparticles has been developed as directly patternable material for the realization of two dimensional (2D) plasmonic gratings through nanoimprint lithography. An optical and electrical characterization of the ITO-based films has been performed. The imprinting process has been optimized in order to obtain a faithful negative replication of an array of nanopyramids on a hard master, in terms of period and depth of the structures. The morphology of the fabricated 2D gratings has been characterized with Atomic Force and Scanning Electron Microscopy. Experimental measurements and theoretical simulations of the far-field properties of the ''naked'' photonic grating, before coupling with an emitter or depositing a thin metal film on top, have been carried out for incident light in the 300-1500nm wavelength range. A good qualitative agreement for transmittance data has been obtained. Simulated data for reflectance properly reproduce the experimental result only at long wavelengths, in the near-infrared region. Suggestions for further model implementations are proposed. The plasmonic architecture will be eventually designed and realized by applying the suitable metal coating.