Optical properties of single-phase β-FeSi2 films fabricated by electron beam evaporation

Single-phase semiconducting iron disilicide (β-FeSi2) films on silicon substrate were fabricated by electron beam evaporation (EBE) technique. For preventing the oxidation of Fe film, silicon/iron/silicon sandwich structure films with different thickness of silicon and iron were deposited and then annealed at different temperatures. X-ray diffraction (XRD), Raman and Fourier transform infrared spectroscopy (FTIR) measurements were carried out to study the phase distribution and crystal quality of the films. Single-phase β-FeSi2 with high crystal quality was achieved after annealing at 800 °C for 5 h. An apparent direct bandgap Eg of approximately 0.85-0.88 eV was observed in the β-FeSi2 films. It is considered that the silicon/iron/silicon sandwich structure is suited for formation of single-phase β-FeSi2 with high crystal quality.