Influence of nanoparticle height on plasmonic resonance wavelength and electromagnetic field enhancement in two-dimensional arrays

A detailed experimental and theoretical study of the plasmonic properties of silver nanoparticle arrays as a function of nanoparticle height is presented. Specifically, several square periodic arrays have been fabricated by electron beam lithography and characterized via transmission spectroscopy measurements The same arrays have also been numerically investigated via finite-difference time-domain calculations of their scattering and absorption cross sections and steady-state field intensity distributions. The results of this Study show that the collective plasmonic resonances of these these arrays can be effectively blueshifted by increasing the nanoparticle height, while at the same time maximizing the average field enhancement in the substrate and maintaining small absorption losses. This approach can therefore be used to extend the spectral reach of lithographically defined metallic nanoparticle arrays for practical applications such as light-emission efficiency enhancement. (D 2009 American Institute of Physics. [doi-10.1063/1.3255979]