Titanium nitride-gold nanoislands: Harnessing electrical and optical properties for enhanced localized surface plasmon resonance sensing

Titanium nitride-gold nanoislands (TANIs) are experimentally investigated to explore their electrical and optical properties induced by the incorporation of Au into TiN. A film is first fabricated on a glass substrate using the radio frequency (RF) magnetron sputtering technique at 300 K, with a thickness of approximately 20 nm (+/- 2.5 nm) and an Au:TiN ratio of 0-0.47. Subsequent thermal annealing provides a nanoisland structure of TiN-Au. Characterization techniques such as X-ray diffraction and X-ray photoelectron spectroscopy confirmed the presence of TiN and Au in the fabricated TiN-Au nanoislands. Spectroscopic ellipsometry measurements show that the TANIs posses excellent optical properties. Furthermore, numerical evaluations of energy dissipation are conducted to assess carrier transport deterioration due to the inelastic scattering effects in the TANIs and the inclusion of Au in the nanostructure significantly have reduced the dielectric loss tangent at energies greater than 4.5 eV, compensating for high losses and enhancing optical performance. The biosensing capability of TANIs is also demonstrated with the sensing of biotin, such that a strong biotin-phase response relationship is formed with a limit of detection of 0.842 ng/ml. This study contributes valuable insights into the electrical, optical and biosensing properties of TANIs, providing direction for sensing applications, where the optimization of the TANIs structure could bring about advancements in optical performance and pave the way for the potential design of novel plasmonic sensors.