Morphology and Surface Plasmon Resonances of Silver Nanocomposite Layer-by-Layer Films

Fabrication of large-area nanocomposite thin films containing single or multiple layers of metal-nanoparticle arrays is described. The method is based on successive deposition of oxide and metal layers of which the latter is ion beam mixed. This technique is shown to be well suited for synthesizing silver-nanoparticle arrays embedded in dielectric layers of Al₂O₃ and TiO₂. The fabricated nanoparticles are of ellipsoidal shape and have diameters of several tens of nanometres. In the bilayer structures, where two nanoparticle arrays are separated by a layer of dielectric, the particles are observed to align themselves in accordance with the positions of the nanoparticles in the adjacent layer. Surface plasmon resonances of the produced mono- and bilayer nanocomposites are examined experimentally, in the spectral range from 250 to 850 nm, by measuring the extinction and diffusive reflection spectra of the samples. These experiments reveal strong dependence of the plasmon resonant scattering on the nanoparticle arrangement and material characteristics of the interlayer chosen.