Sci. Rep. 6, 30605 (2016)

Silver is typically the metal of choice for many plasmonics applications thanks to its relatively low dissipation at optical wavelengths, in particular the He–Ne laser wavelength of 632.8 nm. In much of the visible regime, the ratio of the imaginary to real part of silver's permittivity is considered to be small, leading to low-loss plasmonics. Now, Yajie Jiang, Supriya Pillai and Martin Green at the University of New South Wales, Sydney, Australia report that existing literature on the optical constants of silver are inconsistent leading to inappropriate assumptions sometimes being made for the optical loss in plasmonics experiments as a result. While the optical constants of silver films depend on deposition parameters, such as deposition rate and annealing conditions, the team have shown a way to fabricate silver films with consistent optical constants by exploiting silver nitride membranes. Most importantly, they have carefully characterized the optical constants of the films using multiple-angle, spectrometric ellipsometry and shared the fabrication recipe to enable researchers to replicate the films. The team hopes that the improved data set of silver's optical constants will reduce underestimation of loss when practical applications of plasmonic structures are evaluated.