ZnO-AuxCu1-x Alloy and ZnO-AuxAl1-x Alloy Vertically Aligned Nanocomposites for Low-Loss Plasmonic Metamaterials.

Robynne L Paldi,Anter El-Azab,Haiyan Wang,Nirali A Bhatt,Juanjuan Lu,Yash Pachaury,Aleem Siddiqui,Zihao He,Xinghang Zhang

doi:10.3390/molecules27061785

Robynne L Paldi, Anter El-Azab + Show 7 more

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https://doi.org/10.3390/molecules27061785

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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.

Highlights

Hybrid plasmonic metamaterials are materials artificially constructed with more than one material, with plasmonic properties as well as other exotic properties, resulting from the constructed hybrid structures
Some of the exotic optical functionalities include hyperbolic dispersion, epsilon-near-zero (ENZ) permittivity and nanoscale light manipulation. These properties are created in anisotropic nanostructures in which in one direction it behaves as a dielectric material and in the perpendicular direction it behaves as a metal [1]
ZnO-AuxAl1−x nanocomposite thin films were grown through a a two-step pulsed laser deposition

Summary

Introduction

Hybrid plasmonic metamaterials are materials artificially constructed with more than one material, with plasmonic properties as well as other exotic properties, resulting from the constructed hybrid structures. Some of the exotic optical functionalities include hyperbolic dispersion, epsilon-near-zero (ENZ) permittivity and nanoscale light manipulation These properties are created in anisotropic nanostructures in which in one direction it behaves as a dielectric material and in the perpendicular direction it behaves as a metal [1]. The periodic nature of the material enables a photonic band gap, whereby certain wavelengths of light are inhibited from propagation Such a nanostructure can be achieved by directly embedding metallic nanowire into a dielectric medium [2–4]. Direct integration of hyperbolic metamaterials to optical devices has been predicted to allow for subdiffraction imaging [5]

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