The properties of various CrxNy films grown by direct current (DC) reactive
sputtering process with different values of nitrogen partial pressures (0,
2?10-4, 3.5?10-4 and 5?10-4 mbar) were studied. The structural analysis of
the samples was performed by using X-ray diffraction and transmission
electron microscopy (TEM), while an elemental analysis was realized by means
of Rutherford backscattering spectrometry. By varying nitrogen partial
pressure the pure Cr layer, mixture of Cr, Cr2N and CrN phases, or
single-phase CrN was produced. TEM analysis showed that at pN2 = 2?10-4 mbar
the layer has dense microstructure. On the other hand, the layer deposited at
the highest nitrogen partial pressure exhibits pronounced columnar structure.
The optical properties of CrxNy films were evaluated from spectroscopic
ellipsometry data by the Drude or combined Drude and Tauc-Lorentz model. It
was found that both refractive index and extinction coefficient are strongly
dependent on the dominant phase formation (Cr, Cr2N, CrN) during the
deposition process. Finally, the electrical studies indicated the metallic
character of Cr2N phase and semiconducting behaviour of CrN.