Controlling the Optical Properties of Plasmonic Disordered Nanohole Silver Films

Abstract

Disordered nanohole arrays were formed in silver films by colloidal lithography techniques and characterized for their surface-plasmon activity. Careful control of the reagent concentration, deposition solution ionic strength, and assembly time allowed generation of a wide variety of nanohole densities. The fractional coverage of the nanospheres across the surface was varied from 0.05-0.36. Electrical sheet resistance measurements as a function of nanohole coverage fit well to percolation theory indicating that the electrical behavior of the films is determined by bulk silver characteristics. The transmission and reflection spectra were measured as a function of coverage and the results indicate that the optical behavior of the films is dominated by surface plasmon phenomena. Angle-resolved transmission and reflection spectra were measured, yielding insight into the nature of the excitations taking place on the metal films. The tunability of the colloidal lithography assembly method holds much promise as a means to generate customized transparent electrodes with high surface plasmon activity throughout the visible and NIR spectrum over large surface areas.

Plasmon-induced photonic and energy-transfer enhancement of solar water splitting by a hematite nanorod array

“…The periodicity of the plasmonic pattern can affect the plasmonic properties of the metal nanostructures 49,50 . As a control sample, a disordered Au hole array pattern was fabricated with the same hole size but without long-range order ( Supplementary Fig.…”

On the dielectric function tuning of random metal-dielectric nanocomposites for metamaterial applications

“…Fabrication of a composite consisting of a metal matrix with isolated dielectric inclusions by thin film deposition techniques used in this and other studies [22,23] might be complex, since the island growth is characteristic for metals and not dielectrics. Alternatively, there are several techniques for fabrication of metal films with isolated dielectric inclusions, specially voids: nanoporous gold from cluster beam deposition [48], disorder nanohole arrays from colloidal lithography [49] or nanoscale casting with electrochemical deposition [50]. Indeed, the effective dielectric function of nanoporous gold determined in reference [48] show absence of localized surface plasmon resonance in the visible range, as suggested from the above theoretical analysis.…”

Polymer blend lithography for metal films: large-area patterning with over 1 billion holes/inch2

“…The photons couple to surface plasmons on the incident side of a nanohole film. These surface plasmons convert back to photons after they propagate through the holes to the opposite side of the film [26]. In recent years, also the colloidal lithography method has been used to study the surface plasmonics of random nano-hole arrays in metal films [26–27].…”