In the investigation of thin films of transition metal nitrides, an
essential role is played by the accurate determination of their chemical
composition. Actually the chemical composition depends on the deposition
parameters and influences the optical properties. These relations are
illustrated in thin films of TiNx and (Ti1-yVy)N-x deposited by reactive
magnetron sputtering from composite targets of the elements. By
variation of the nitrogen partial pressure and the target composition,
different samples have been obtained. The chemical composition has been
measured by electron probe microanalysis at low irradiation voltages.
The optical properties are evaluated by ex-situ ellipsometry. Using the
screened Drude model, they are correlated with the differences in
composition. Adding vanadium or nitrogen in Ti-N is shown to have the
same effect on the optical properties.