Controlling the color and effective refractive index of metal-anodic Aluminum Oxide (AAO)–Al nanostructures: Morphology of AAO

Metal-anodic aluminum oxide (AAO)−Al nanostructures have been deposited by using sputtering for the metal layer deposition and a two-step anodization process in different electrolytes to produce self-ordered anodic aluminum oxide films. The effect of the morphological parameters of AAO films (such as thickness, pore diameter, interpore distance, and porosity) on the optical properties was studied. The UV−vis reflectance properties as a function of the thickness for the different electrolytes of metal-AAO−Al films were analyzed in order to obtain the color diagrams and the effective refractive indexes of the films. The effective refractive index was found to depend on the thickness and porosity of AAO films. The change in color observed in metalAAO−Al nanostructures is due to the thickness and porosity of the AAO films. In order to verify the experimental results, UV−vis reflectance spectra of AAO− Al films were simulated using commercially available finite element simulation softwareThe authors would like to acknowledge financial support from Commission for Technology and Innovation (CTI-16977.2 PFNM-NM) of the Swiss Confederation. C.V.M. would like to acknowledge funding from the Marie Curie Actions cofound program of the EU’s Seventh Research Framework Program (FP7).Peer reviewe