  A current approach to depositing highly plasmonic titanium nitride films
using the magnetron sputtering technique assumes that the process is performed
at temperatures high enough to ensure the atoms have sufficient diffusivities
to form dense and highly crystalline films. In this work, we demonstrate that
the plasmonic properties of TiN films can be efficiently tuned even without
intentional substrate heating by influencing the details of the deposition
process and entailed films' stoichiometry and microstructure. We also discuss
the dependence of the deposition time/films' thickness on the optical
properties, which is another degree of freedom in controlling the optical
response of the refractory metal nitride films. The proposed strategy allows
for robust and cost-effective production of large-scale substrates with good
plasmonic properties in a CMOS technology-compatible process that can be
further processed, e.g., structurized. All reported films are characterized by
the maximal values of the plasmonic Figure of Merit (FoM = -e1/e2) ranging from
0.8 to 2.6, and the sample with the best plasmonic properties is characterized
by FoM at 700 nm and 1550 nm that is equal 2.1 in both cases. These are
outstanding results, considering the films' polycrystallinity and deposition at
room temperature onto a non-matched substrate.
