Solid-state reaction in Ni/Si multilayered films, characterized by magneto-optical and optical spectroscopies

Abstract

Abstract Solid-state reactions, induced by ion-beam mixing (IBM) and thermal annealing, in Ni/Si multilayered films (MLF) with an overall stoichiometry of Ni2Si, NiSi and NiSi2, and with a constant Ni sublayer thickness (nominally, 3.0 nm), were studied by optical and magneto-optical spectroscopies as well as X-ray diffraction (XRD). The layer mixing was performed with Ar+ ions of an energy of 80 keV and a dose of 1.5 × 1016 Ar+/cm2. It was shown that the IBM leads to structural changes in the Ni/Si MLF, which cannot be easily detected by XRD but are recognized by optical tools. An annealing at 1073 K of the Ni/Si MLF with an overall stoichiometry of NiSi and NiSi2 induces formation of predominantly the η-NiSi and the NiSi2 phases, respectively. IBM of all the investigated Ni/Si MLF leads to the formation of regions with a short-range order of the crystalline NiSi silicide, and of Ni2Si (and/or Ni3Si) additionally for the Ni/Si MLF with an overall stoichiometry of Ni2Si.