Colloidal lithography is widely used as a low cost and large-area deposition approach, alternative to the conventional small-area expensive lithographic techniques, for the fabrication of short-range ordered sub-wavelength metallic nanostructures. This paper contributes to the understanding of the impact of the fabrication protocol of a colloidal mask on the optical and sensing properties of short range-ordered nanohole (NH) distributions fabricated by colloidal lithography in optically thin (20 nm thick) gold films. We consider polystyrene nanospheres (PS-NSPs) with a nominal diameter of 80 nm, electrostatically adsorbed from a salt-free colloidal solution onto a polydiallyldimethylammonium (PDDA) countercharged monolayer. By avoiding the conventional polyelectrolyte multilayer and based on the interplay between the deposition times of both PDDA and PS-NSPs, we demonstrate effective simplification of the commonly applied deposition protocol and effective tuning of the NH-to-NH spacing (d NN ) with negligible agglomeration. Comparison with NH samples prepared by salt-containing colloidal solutions points out the negative impact of salt addition on the optical properties. The effective tuning of d NN obtained by our protocol demonstrates highly correlated disorder under unsaturated adsorption and allows a discussion on the analogies of the optical response between long- and short- range ordered NH systems, which is a still debated topic. By Fast Fourier Transform of autocorrelation images of scanning electron microscopy micrographs we demonstrate quantitatively, rather than in principle, the correspondence between an inherent ordering length-scale and d NN . As optical transducers for detecting refractive index changes, our samples exhibit significant bulk sensitivity (∼309 nm RIU -1 ) in the framework of short range ordered NH systems.
Gold nanoholes fabricated by colloidal lithography: Novel insights into nanofabrication, short-range correlation and optical properties / Cesaria M.; Taurino A.; Manera M.G.; Minunni M.; Scarano S.; Rella R.. - In: NANOSCALE. - ISSN 2040-3364. - ELETTRONICO. - 11:(2019), pp. 8416-8432. [10.1039/c8nr09911a]
Gold nanoholes fabricated by colloidal lithography: Novel insights into nanofabrication, short-range correlation and optical properties
CESARIA, MAURA;Manera M. G.;Minunni M.;Scarano S.;Rella R.
2019
Abstract
Colloidal lithography is widely used as a low cost and large-area deposition approach, alternative to the conventional small-area expensive lithographic techniques, for the fabrication of short-range ordered sub-wavelength metallic nanostructures. This paper contributes to the understanding of the impact of the fabrication protocol of a colloidal mask on the optical and sensing properties of short range-ordered nanohole (NH) distributions fabricated by colloidal lithography in optically thin (20 nm thick) gold films. We consider polystyrene nanospheres (PS-NSPs) with a nominal diameter of 80 nm, electrostatically adsorbed from a salt-free colloidal solution onto a polydiallyldimethylammonium (PDDA) countercharged monolayer. By avoiding the conventional polyelectrolyte multilayer and based on the interplay between the deposition times of both PDDA and PS-NSPs, we demonstrate effective simplification of the commonly applied deposition protocol and effective tuning of the NH-to-NH spacing (d NN ) with negligible agglomeration. Comparison with NH samples prepared by salt-containing colloidal solutions points out the negative impact of salt addition on the optical properties. The effective tuning of d NN obtained by our protocol demonstrates highly correlated disorder under unsaturated adsorption and allows a discussion on the analogies of the optical response between long- and short- range ordered NH systems, which is a still debated topic. By Fast Fourier Transform of autocorrelation images of scanning electron microscopy micrographs we demonstrate quantitatively, rather than in principle, the correspondence between an inherent ordering length-scale and d NN . As optical transducers for detecting refractive index changes, our samples exhibit significant bulk sensitivity (∼309 nm RIU -1 ) in the framework of short range ordered NH systems.File | Dimensione | Formato | |
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