BAND-STRUCTURE AND ELECTRONIC-PROPERTIES OF FESI AND ALPHA-FESI(2)

The results of self-consistent linear muffin-tin orbital calculations for the ordered end members of the FeSi1+x series, i.e., FeSi (x = 0) with a CsCl structure and alpha-FeSi, (x = 1) with a tetragonal struct ure, predict semimetallic behavior for FeSi and metallic behavior and higher stability for alpha-FeSi2. The valence band density of state fe atures of the alpha-FeSi2 differ slightly from those of the cubic fluo rite (gamma-FeSi2). The analysis of the valence band photoemission spe ctra taken on silicide thin films epitaxially grown on Si(111) substra tes estimates the composition of the mono- and disilicide phases prese nt in the annealed films but does not determine the proposed formation of the distorted fluorite structure (alpha-FeSi2) well below its bulk stabilization temperature of 950-degrees-C.