Optical properties of oxidative controlled titanium nitride thin films
Scientific Achievement:
Pulsed laser deposition (PLD) assisted fabrication of epitaxial titanium nitride (TiN) and titanium oxynitride (TiNO) thin films with noble metal-like reflectivity, large negative dielectric constant, and figure of merit (top figure, middle panel). The optical properties of TiN and TiNxOy films are analyzed using a model of a thin film on a thick substrate involving air–film, film–substrate, and substrate–air interfaces. (J. Phys. Chem. Supplementary Cover, Feb 20, 2025, Vol 129, No. 9, Left panel)
Research Details:
In-situ pulsed laser method was used to make epitaxial TiN and TiNO films
Characterizations were carried out using XRD, XRR, AFM, XPS, Hall, Optical, and E-Chem Measurements
A 30° rotational matching of three 2D unit cells of TiN/TINO with one 2D unit cell of sapphire substrate giving (111) oriented growth of TiN films (bottom figure, middle panel)
Significance and Impact:
The advantages of oxide derivatives of TiN are the continuation of similar free electron density as in TiN and the acquisition of additional features such as oxygen-dependent semiconducting with tunable bandgap
From the experimental and theoretical studies, a multi-layer optical model has been proposed for the TiN/TiNO epitaxial thin films for obtaining individual complex dielectric functions from which many other optical parameters can be calculated.
Due to superior plasmonic properties, TiN/TiNO have the potential to overcome the limitation of noble metal for plasmonic applications