Tailoring of UV/violet plasmonic properties in Ag, and Cu coated Al concaves arrays

UV plasmonics is of particular interest because of large variety of applications, where the higher energy plasmon resonances would advance scientific achievements, including surface-enhanced Raman scattering (SERS) with UV excitation, ultrasensitive label-free detection of important biomolecules absorbing light in the UV, or the possibility for exerting control over photochemical reactions. Despite its potential, UV plasmonics is still in its infancy, mostly due to difficulties in fabrication of reproducible nano-structured materials operating in this high energy range. Here, we present a simple electrochemical method to fabricate regular arrays of aluminum concaves demonstrating plasmonic properties in UV/violet region. The method enables the preparation of concaves with well-controlled geometrical parameters such as interpore distance (D-c), and therefore, well controllable plasmon resonances. Moreover, the patterning is suitable for large scale production. The UV/violet properties of Al concaves can be further fine-tuned by Ag and Cu metals. The refractive index sensitivity (RIS) increases after the metals deposition as compared to RIS of pure Al nanohole arrays. The highest RIS of 404 nm/RIU was obtained for Cu coated Al nanoconcaves with the D-c =460.8 nm, which is similar or better than the RIS values previously reported for other nanohole arrays, operating in visible/near IR range. (C) 2014 Published by Elsevier B.V.