COMPOSITIONAL AND MICROSTRUCTURAL ANALYSES OF Fe-Pd NANOSTRUCTURED THIN FILMS

Fe-Pd thin films with various compositions and thicknesses were produced with electrodeposition using the constant potentials from 1.0 to 1.3 V. The FEGSEM and AFM analyses revealed a smooth, nanostructured surface morphology of the films, with more granular features appearing at more negative potentials. The high-resolution FEGSEM images of the film cross-sections and complementary calculations using the data from the EDS thin-film analyses were used to determine the film thicknesses, showing that ultrathin films 50 nm to 120 nm were obtained. The chemical compositions of the films were measured with a quantitative, EDS electron-probe microanalysis using two independent approaches: (i) a low-voltage analysis (LVEDS) and (ii) a variable-voltage analysis with a dedicated thin-film-analysis (TFA) method. Both approaches were properly modified and optimized on the basis of the Monte Carlo simulation data. The results showed that the composition of the Fe-Pd films was close to the preferred equiatomic Fe50Pd50 stoichiometry (which is important for achieving good magnetic properties) and was obtained at 1.3 V and 1.2 V. At the more positive potentials, the Fe-Pd films became Pd rich. The best agreement between the LVEDS and TFA quantitative results was achieved for the Fe-Pd films that were thicker than 80 nm, and a slight discrepancy within the 10 % relative between the LVEDS and TFA values was observed for the films thinner than 70 nm. The faster LVEDS approach is suitable for routine analyses of numerous Fe-Pd samples, to obtain the information about a film composition in a short time. The more demanding TFA approach was found to be very appropriate for accurate compositional analyses of the Fe-Pd ultrathin films and for determining the film thickness.