Strain-Driven In-plane Ordering in Vertically Aligned ZnO-Au Nanocomposites with Highly Correlated Metamaterial Properties.

Hyperbolic metamaterials demonstrate exotic optical properties that are poised to find applications in subdiffraction imaging and hyperlenses. Key challenges remain for practical applications, such as high energy losses and lack of hyperbolic properties in shorter wavelengths. In this work, a new oxide-metal (ZnO-Au) hybrid-material system in the vertically aligned nanocomposite thin-film form has been demonstrated with very promising in-plane two-phase ordering using a one-step growth method. Au nanopillars grow epitaxially in the ZnO matrix, and the pillar morphology, orientation, and quasi-hexagonal in-plane ordering are found to be effectively tuned by the growth parameters. Strong surface plasmon resonance has been observed in the hybrid system in the UV-vis range, and highly anisotropic dielectric properties have resulted with much broader and tunable hyperbolic wavelength regimes. The observed strain-driven two-phase in-plane ordering and its novel tunable hyperbolic metamaterial properties all demonstrate strong potential for future oxide-metal hybrid-material design toward future integrated hybrid photonics.