2, Catedrático CONACyT, Ciudad de Mexico, , Mexico
In nanoscale electronic, photonic and plasmonic devices, feature dimensions shrink towards a critical limit, and new experimental approaches have to be explored in lithographic patterning to create ordered arrays of metallic nanostructures with useful optical properties. In this work, spherical submicrometer-sized colloidal silica particles were prepared by sol-gel and deposited onto silica glass plates by means of a spin coater system. By combining MeV ion implantation (Au, Ag ions) and nanosphere lithography, this silica particle monolayer acts as a mask to create regular arrays of metallic nanoscale features embedded in the silica plate. By this way, after removal of the silica particles and an adequate thermal annealing of the as-implanted samples, the formation of metallic nanostructures was confirmed by the presence of the corresponding surface plasmon resonance (SPR) in the optical absorption spectra. In order to modify the shape of such quasi-spherical nanoparticles embedded in the silica matrix, some of the samples were irradiated at room temperature with 8 MeV Si ions, leading to the formation of elongated metallic nanoparticles, achieving then the tuning of the SPR and the nonlinear optical properties. The size and shape of the arrays of silica particles and the embedded metallic nanoparticles were studied by scanning and transmission electron microscopy, respectively. The long range order of both the self-assembled monolayer of silica particles and the metallic nanoparticle arrays were characterized by a Fast Fourier Transform study. The plasmonic properties of the metallic nanostructures were characterized by optical absorption measurements as a function of the Si ion irradiation experimental parameters.