Ion Beam Etching of Anodic Aluminium Oxide Barrier Layer for Au Nanorod-Based Hyperbolic Metamaterialsстатья
Статья опубликована в высокорейтинговом журнале
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Дата последнего поиска статьи во внешних источниках: 10 июля 2024 г.
Аннотация:Porous anodic aluminium oxide (AAO) is widely used as a template for the electrodeposition of ordered arrays of one-dimensional nanostructures. Prior to template filling, the barrier layer, which blocks the pores at their bases, should be removed. However, the increase in AAO porosity during wet-chemical etching of the barrier layer is unavoidable that can limit further application of the templates. In this study, we report the kinetics of ion beam etching of the AAO barrier layer and the application of the technique for preparing AAO templates with the lowest possible porosity: 8% for the AAO films obtained in 0.3 M oxalic acid at 40 V. The fabrication of Au nanorod-based hyperbolic metamaterials (HMMs) with a certain spectral position of epsilon-near-zero point is demonstrated. Transmission spectra measurement and simulation give self-consistent values of gold volume fraction in the range from 7.3% to 8.4% confirming the high reproducibility of the proposed technique for AAO barrier layer etching. Such low volume fraction of metal makes Au nanorod-based HMMs promising candidates for the use in nanophotonic devices with tunable properties that are sensitive to the geometrical parameters of the structural elements. HMMs prepared using templates after chemical etching of the barrier layer possess a higher metal volume fraction and demonstrate a weaker dependence of the ENZ position on the nanorod length.