Engineering the structural, plasmonic, and optical properties of multilayered aluminum-doped zinc oxide metamaterial grown by pulsed laser deposition.

We engineer a tunable multilayered aluminum-doped zinc oxide metamaterial with low-loss and high-carrier concentration using the pulsed laser deposition. The results of the scanning probe microscopy study show excellent surface quality with a root mean square roughness value of 1.88±0.07  nm. The transmission electron microscopy measurements indicate a clear layer-by-layer structure of the multilayered samples. The optical permittivity results, obtained using the ellipsometry approach, show that the hyperbolic dispersion of the dielectric constant [Re (ε)>0, Re (ε)<0] is achieved in the near-IR spectral range. The low imaginary part of the optical permittivity Im (ε)=0.003 and Im (ε)=0.011 is achieved for the optimized sample at the epsilon-near-zero spectral point [Re (ε)=0 at 1885 nm]. The results of the ellipsometry analysis show that the systematic variation of different fabrication conditions, such as the AZO/ZnO ratio, the thickness of an individual layer, the film's total thickness, and the deposition temperatures, allows for tuning the plasma frequency ω and damping frequency γ of the investigated samples, which is a promising approach for the future precise engineering of linear and nonlinear optical properties of multilayered aluminum-doped zinc oxide metamaterial.