Abstract
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.
Highlights
Revisiting the Optical Dispersion of Aluminum-Doped Zinc Oxide New Perspectives for Plasmonics and Metamaterials Shabani, Alireza; Khazaei Nezhad, Mehdi; Rahmani, Neda; Mishra, Yogendra Kumar; Sanyal, Biplab; Adam, Jost
We investigated the structural properties of aluminum-doped zinc oxide (AZO)
AZOU2 indicates 2.08% Al-doped in zinc oxide (ZnO) with included Hubbard potential while AZO2 shows the same level of doping but without U parameter
Summary
We calculate the electronic and optical properties of Al-doped ZnO compounds using first-principles calculations. To this end, we used the SIESTA package[19] within LDA, to simulate 2 ⨯ 2 ⨯ 2 and 6 ⨯ 2 ⨯ 2 supercells of zinc oxide (ZnO), having 16 and 48 zinc (oxygen) atoms (shown in Figure 1), respectively. The DFT þ U approach looks to compensate for the relevant shortcoming by adding an orbitaldependent term to the DFT potential This model is used for highly correlated materials, in which the on-site Coulomb interactions are strong for localized d and f electrons that cause the large Coulomb repulsion between localized electrons not properly treated by a functional such as the LDA or generalized gradient approximation. It turned out that U values of 14 and 7 eV for Ud and Up, respectively, best agree with the experimental results for the bandgap, DOS, and optical dielectric function
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