STRUCTURAL AND ELECTRONIC-PROPERTIES OF METASTABLE EPITAXIAL FESI1+X FILMS ON SI(111)

We have investigated the epitaxial growth and the electronic properties of a metallic metastable FeSi phase crystallizing with the CsCl structure on Si(111). Upon annealing below 500-degrees-C the stoichiometry of thin films (<20 angstrom) evolves towards FeSi2 with no change of symmetry, i.e., the defect CsCl structure with a statistical occupation of metal sites remains epitaxially stable for all FeSi1+x (0 less-than-or-equal-to x less-than-or-equal-to 1). Films thicker than approximately 20 angstrom exhibit a transition to the cubic epsilon-FeSi phase. The electronic band structure of FeSi (CsCl) has been calculated self-consistently using the full-potential linear augmented-plane-wave method.