Correlation between electrical direct current resistivity and plasmonic properties of CMOS compatible titanium nitride thin films

Damping distances of surface plasmon polariton modes sustained by different. thin titanium nitride (TiN) films are measured at the telecom wavelength of 1.55 mu m. The damping distances are correlated to the electrical direct current resistivity of the films sustaining the surface plasmon modes. It is found that TiN/Air surface plasmon mode damping distances drop non-linearly from 40 to 16 mu m as the resistivity of the layers increases from 28 to 130 mu Omega.cm, respectively. The relevance of the direct current (dc) electrical resistivity for the characterization of TiN plasmonic properties is investigated in the framework of the Drude model, on the basis of parameters extracted from spectroscopic ellipsometry experiments. By probing a parametric space of realistic values for parameters of the Drude model, we obtain a nearly univocal dependence of the surface plasmon damping distance on the dc resistivity demonstrating the relevance of dc resistivity for the evaluation of the plasmonic performances of TiN at telecom frequencies. Finally, we show that better plasmonic performances arc obtained for TiN films featuring a low content of oxygen. For low oxygen content and corresponding low resistivity, we attribute the increase of the surface plasmon damping distances to a lower confinement of the plasmon field into the metal and not to a decrease of the absorption of TiN. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement