Structural and optical analysis of beta-FeSi2 thin layers prepared by ion-beam synthesis and solid-state reaction

The beta -FeSi2 phase was fabricated using two different techniques: ion-be am synthesis and solid-stare reaction of a thin Fe layer with Si substrate. The crystal structure of the films was investigated by grazing incident as ymmetric x-ray diffraction. The generalized matrix method was used to obtai n the dispersions of the absorption coefficient alpha (E) and of the refrac tive index n(E) from the experimental transmittance and reflectance spectra , accounting for the surface and interface roughness. From alpha (E) and n( E) dependences a direct band-gap enegy, E-g = 0.80 eV was determined. When interpreting quantitatively the alpha (E) dependences, the Burstein-Moss ef fect was considered.