Optical properties of super stoichiometric TiN1 + x thin films

Abstract

Nitrogen-rich titanium nitride (TiN1+x) thin films containing between 70.4at.% and 87.0at.% nitrogen were synthesized and deposited onto single crystal silicon with a (100) crystallographic orientation via the reactive magnetron direct current (DC)-sputtering by systematically varying the process pressure and substrate temperature. The ultraviolet and visible optical properties of these chemically unique TiN1+x thin films have been explored vs. surface roughness and stoichiometry. The specular and diffuse reflectances are linearly coupled to the root mean square surface roughness. The reflectance and absorption were shown to be wavelength dependent. Absorption coefficients for these non-transparent thin films were experimentally determined by monitoring the real-time transient temperature profile of the films and directly correlating the maximum temperature increment to the linear absorption coefficient. The linear absorption coefficient was found to range between 9.11×105 and 3.84×106cm−1 and is strongly coupled to the incident wavelength and nitrogen content. The interaction depths range between 2 and 11nm, indicating interaction only near the film surface.