Tailoring the plasmonic properties of complex transition metal nitrides: A theoretical and experimental approach

Transition metal nitrides (TMNs) are promising materials for developing next-generation photonic devices. A practical way toward high-performance TMNs is to tune their plasmonic properties through different compositions. Here, we investigate the electronic structures and optical properties of TMNs (Ti_1-xZr_xN and Ti_1-xHf_xN, x = 0, 0.25, 0.50, 0.75, and 1) computationally and experimentally. Our calculated dielectric permittivities and quality factors suggest that the overall performance of TMNs is well-tuned by their compositions, supported by our measured data obtained from the 50-nm thick TMN films deposited on sapphire (0001). Particularly, at the dielectric-metallic interface, Ti_0.25Hf_0.75N (ENZ of 401 nm) and Ti_0.50Zr_0.50N (ENZ of 406 nm) show a better dielectric response than the binary TMNs. Ti_0.50Hf_0.50N (ENZ of 457 nm) holds promise for applications requiring efficient energy absorption and enhanced wave manipulation in the near-infrared range. Using mixed ternary TMNs to tune plasmonic properties in the visible and near-infrared regions can thus achieve frequency-targeting photonics applications.