CHARACTERIZATION OF MAGNETRON-SPUTTERED EPSILON-IRON-NITRIDE FILMS

Iron nitride films of 250-450 nn thickness were produced over a wide r ange of compositions by reactive magnetron sputtering. These films wer e analyzed by a combination of conversion electron Mossbauer spectrosc opy (GEMS). Rutherford backscattering spectrometry (RES), resonant nuc lear reaction analysis (RNRA) and X-ray diffraction. The iron and nitr ogen concentration profiles and thus the compositions of the samples w ere determined by RES and RNRA. With the known dependence of the latti ce constant on the nitrogen content for the epsilon-Fe2N1-z nitride it was also possible to determine the composition via the analysis of th e X-ray diffraction pattern. For epsilon-Fe2N1-z (0 less than or equal to z less than or equal to 0.33) the GEMS spectra could be well resol ved in terms of different iron sites (environments), enabling an accur ate determination of the nitrogen content in the 150 nm sampling range near the surface. It has been confirmed experimentally that the param agnetic epsilon-Fe2N1-z phase with z less than or equal to 0.13 also h as two different iron sites. Thus it was possible to compare the compo sitions obtained by the four different methods. For the hexagonal epsi lon iron-nitride phase, Mossbauer spectroscopy proves that it experien ces an ordering of the nitrogen atoms on the interstitial sites.