Revisiting the Optical Dispersion of Aluminum-Doped Zinc Oxide: New Perspectives for Plasmonics and Metamaterials

Due to the high rate of optical losses and the extensive usage of noble metals, alternative plasmonic materials with maximum tunability and low loss are desired for future plasmonic and metamaterial devices and applications. Herein, the potential of aluminum-doped zinc oxide (AZO), one of the most prominent members of the transparent conducting oxide family, is demonstrated, for its applicability in plasmonic metamaterials. Using first-principles density functional theory, combined with optical calculations, AZO-based, plasmonic split-ring resonators (SRRs) as model examples are showcased. The results match with experimental reports for the optical dielectric functions of pure and 2.08% Al-doped zinc oxide (ZnO), if the Hubbard model to the local density approximation is applied. The broadband optical dispersion data for varying dopant concentrations (0%, 2.08%, and 6.25%) are extracted and provided. The subsequent optical response analyses show the existence of pronounced plasmons and inductor-capacitor modes in Al-doped ZnO SRRs and an enhancement in metallic characteristics and plasmonic performance of AZO upon increasing Al concentration. The findings predict AZO as a low-loss plasmonic material with promising capability for enhancing future optoelectronics applications. The method introduces a new, versatile approach to design future optical materials of arbitrary geometry.