Infrared metamaterial by RF magnetron sputtered ZnO/Al:ZnO multilayers

Abstract

Hyperbolic metamaterials create artificial optical anisotropy using metallic wires suspended in a dielectric medium, or alternating layers of a metal and dielectric. Here we fabricated ZnO/Al:ZnO (AZO) multilayers by the RF magnetron sputtering deposition technique. Our fabricated multilayers satisfy the conditions required for a type I hyperbolic metamaterial. The optical response of individual AZO and ZnO films, as well as the multilayered film were investigated via angular transmittance and spectroscopic ellipsometry measurements. The optical response of the multilayered system is predicted using the nonlocal-corrected Effective Medium Approximation (EMA). The spectroscopic ellipsometry data of the multilayered system was modeled using a uniaxial material model and EMA model. Both theoretical and experimental studies validate the multilayers undergo a hyperbolic transition at a wavelength of 2.2 μm.

Optics with hyperbolic materials [Invited]

“…Au/SiO 2 multilayers were fabricated for the observation of highk BPPs excited with the help of a Si prism [34]. Apart from Au as a material for conductive films for visible to near-IR wavelengths [16,34], other materials like silver (Ag) [11,[59][60][61], titanium nitride (TiN) [62], aluminum-doped zinc oxide (AZO) [63], and doped semiconductors [10] have been reported plasmonic constituent layers of HMMs. In case of semiconductors, multilayer HMM can be made of the same semiconductor but with different doping levels: highly doped layers serve as metal and low doped layers serve as dielectric [15].…”