Band structure and electronic properties of FeSi and α-FeSi2

Abstract

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 α-FeSi2 (x=1) with a tetragonal structure, predict semimetallic behavior for FeSi and metallic behavior and higher stability for α-FeSi2. The valence band density of state features of the α-FeSi2 differ slightly from those of the cubic fluorite (γ-FeSi2). The analysis of the valence band photoemission spectra taken on silicide thin films epitaxially grown on Si(111) substrates estimates the composition of the mono- and disilicide phases present in the annealed films but does not determine the proposed formation of the distorted fluorite structure (α-FeSi2) well below its bulk stabilization temperature of 950 °C.