Metastable phases of cobalt-ironsilicide formed by sequential implantationof Co and Fe in Si (111)

By implanting Co and Fe in sequence into Si (111), metastable ternary Co1-x FexSi2 phases were formed. Mossbauer effect measurements showed three reson ance line components in the spectrum. Comparison of the central shift (CS) values of the components with those appearing in the stable ternary phases indicated that iron atoms are positioned in the substitutional Co site, in the empty cube of the fluorite-type lattice and in CsCl-like B2 structures. It was found that the CS values of two components are in the velocity rang e of the values obtained for the metastable gamma-FeSi2 synthesized using v arious methods. This result suggests the existence of a similar structure. (C) 2000 American Institute of Physics. [S0003-6951(00)01414-5].