COMPOSITION ANALYSIS OF CO DOPED FESIX FILMS BY COMBINING STANDARD AND HEAVY-ION RBS

In a UHV deposition system, thin films of Co doped FeSix were grown on Si (111) substrates by coevaporation of Co, Fe and Si from three sepa rately controlled sources. Heavy-ion RES (15 MeV N-14(4+)) providing a sufficiently high mass resolution was applied to determine the Co/Fe ratio. For a Co content of up to [Co]/([Co] + [Fe]) approximate to 0.3 a linear correlation was found between the relative Co evaporation ra te and the concentration of Co in the films. The composition analysis was completed by standard RES (1.4 MeV He-4(+)) for more reliable valu es of the mean Si/metal ratio due to the smaller influence of multiple scattering processes in the spectrum region relevant to Si. IR phonon spectra of the FeSix:Co films show characteristic changes which corre late with the Co concentration measured by RES. (C) 1998 Elsevier Scie nce B.V.