Epitaxial iron silicides: geometry, electronic structure applications

A simultaneous understanding of geometrical and electronic aspects of epitaxial films is crucial whenever a deep knowledge of their fundamental properties is required. A conspicuous example are the epitaxial phases formed by the reaction of Fe and Si. These two elements give rise to a rich variety of bulk binary compounds. In addition to them, metastable phases of different stoichiometries can be epitaxially grown on Si( 111) and Si( 100). These are compounds where the delicate energetic balance giving rise to a particular structure has been altered by epitaxy and phases not formed spontaneously are found. A study on the electronic and geometric structures, covering both stable and metastable phases is presented here. In particular, the properties of metastable FeSi(CsC1) are discussed, when grown both on Si(ll1) and Fe,Si(lOO). The potential applications of this and other iron silicides is discussed in the context of their novel properties