Ansys HFSS Evaluation of Periodic ZnO Nanorod Metamaterial Unit Cell for Terahertz Broadband Antireflection Coatings

This paper proposes a theoretical silicon dioxide (SiO2) solar cell based dielectric metamaterial unit surface consisting of zinc oxide (ZnO) periodic nanorods of bandgap energy of 2.2-2.4eV. It evaluates the absorptive efficiency of the film using S-parameter and Z-parameter testing of magnitude, return/insertion loss, and impedance matching with respect to a frequency band of 0.0014-10.5THz. Terahertz applications of the result are considered due to potential scope for infrared (IR) and microwave (MW) spectral selectivity with ZnO. Calculations of input n-impedance and loss tangents are also presented with emphasis on the exhibition of antireflection to gauge the performance of the thin-film meta-surface in tandem solar cells. The data for the reflectance parameters of this structure, primarily the S11 loss and impedance matching (dB/dB10) are compared to those of prior investigations with different metamaterial coatings on SiO2 solar photovoltaic cells, as well as ZnO nanorods used in photovoltaic applications, to ascertain the cylindrical meta-surface structure with the preset thicknesses of the study being an effective anti-reflector. Application can be extended to other broadband domains requiring plasmonic graded refractive surfaces, in further work.