Eur. Phys. J. B 44, 431-438 (2005)
https://doi.org/10.1140/epjb/e2005-00142-3

Spectroscopic ellipsometric evidence of the solid-state reactions in Ni/Si multilayered films, induced by ion-beam mixing and thermal annealing

¹ Quantum Photonic Science Research Center and Department of Physics, Hanyang University, Seoul, 133-791 Korea
² Institute of Metal Physics, National Academy of Sciences of Ukraine, 36 Vernadsky str, 03142, Kiev-142, Ukraine
³ NTU “Kiev Polytechnical Institute”, 37 Pobedy ave., Kiev, Ukraine
⁴ Department of Physics, Hoseo University, Asan, Choongnam 336-795, Korea

Corresponding author: ^a yplee@hanyang.ac.kr

Received: 27 March 2004
Published online: 30 May 2005

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, while keeping the nominal thickness of Ni sublayer constant (3.0 nm), were studied by using spectroscopic ellipsometry as well as X-ray diffraction (XRD). The mixing was performed with Ar⁺ ions of an energy of 80 keV and a dose of  Ar⁺/cm². Unlike the results of our previous study on Fe/Si MLF [Y.V. Kudryavtsev et al., Phys. Rev. B 65, 104417 (2002)], it was shown that an amorphous phase of NiSi in the B20 phase was formed during deposition independent of the overall stoichiometry of MLF, i.e., the nominal thickness of Si sublayer. IBM leads to some structural changes in the Ni/Si MLF, which cannot be detected by XRD but are confidently recognized by optical tools. A thermal annealing at 673 K of the Ni/Si MLF with an overall stoichiometry of NiSi and NiSi₂ causes formation of the -NiSi phase. The first trace of NiSi₂ phase on the background of the -NiSi phase was detected by XRD after an annealing at 1073 K, while, according to the optical results, NiSi₂ turned out to be the dominant phase for the annealed Ni/Si MLF with an overall stoichiometry of NiSi₂.