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

The beta -FeSi2 phase was fabricated using two different techniques: ion-beam synthesis and solid-stare reaction of a thin Fe layer with Si substrate. The crystal structure of the films was investigated by grazing incident asymmetric x-ray diffraction. The generalized matrix method was used to obtain the dispersions of the absorption coefficient alpha (E) and of the refractive 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 effect was considered.