ZnO-Au<i>_x</i>Cu_1−<i>x</i> Alloy and ZnO-Au<i>_x</i>Al_1−<i>x</i> Alloy Vertically Aligned Nanocomposites for Low-Loss Plasmonic Metamaterials

Abstract

Hyperbolic metamaterials are a class of materials exhibiting anisotropic dielectric function owing to the morphology of the nanostructures. In these structures, one direction behaves as a metal, and the orthogonal direction behaves as a dielectric material. Applications include subdiffraction imaging and hyperlenses. However, key limiting factors include energy losses of noble metals and challenging fabrication methods. In this work, self-assembled plasmonic metamaterials consisting of anisotropic nanoalloy pillars embedded into the ZnO matrix are developed using a seed-layer approach. Alloys of AuxAl1−x or AuxCu1−x are explored due to their lower losses and higher stability. Optical and microstructural properties were explored. The ZnO-AuxCu1−x system demonstrated excellent epitaxial quality and optical properties compared with the ZnO-AuxAl1−x system. Both nanocomposite systems demonstrate plasmonic resonance, hyperbolic dispersion, low losses, and epsilon-near-zero permittivity, making them promising candidates towards direct photonic integration.

Keywords

• ZnO
• Au
• vertically aligned nanocomposite
• low loss
• metamaterials
• Cu