Optical properties of semiconducting iron disilicide thin films

TLDR

Iron disilicide thin films were fabricated by reacting ion‑beam sputtered iron layers with single‑crystal silicon wafers or LPCVD polycrystalline silicon films in a furnace. X‑ray diffraction confirms single‑phase orthorhombic β‑FeSi₂ with impurity levels below detection limits, a direct band gap of 0.87 eV, and a thermal activation energy roughly half that gap, indicating suitability for silicon‑compatible light‑sensitive and light‑emitting devices.

Abstract

Iron disilicide thin films were prepared by furnace reaction of ion beam sputtered iron layers with single-crystal silicon wafers and with low-pressure chemical vapor deposition (LPCVD) polycrystalline silicon thin films. X-ray diffraction indicates the films are single-phase, orthorhombic, β-FeSi2. Impurity levels are below the detection limit of Auger spectroscopy. Normal incidence spectral transmittance and reflectance data indicate a minimum, direct energy gap of 0.87 eV. The apparent thermal activation energy of the resistivity in the intrinsic regime is about half of this minimum optical gap. With such a direct band gap, the material may be suitable for the development of both light-sensitive and light-emitting thin-film devices within the silicon microelectronics technology.