Low-energy carbon ion irradiation-induced phase evolution in thermally treated Ni/Si bilayers

In this paper, we report the effect of low-energy carbon ion irradiation on the thermally annealed nickel-silicon bilayer samples. The primary objective is to analyse and interpret the formation of various nickel silicide phases, their evolution, and stability under ion irradiation. The bilayer samples were fabricated using magnetron sputtering at room temperature, with a 100 nm nickel top layer and a 100 nm silicon buffer layer deposited on a silicon substrate. The deposition was carried out under a base pressure of 7.02 × 10^-7 mbar and a gas pressure of 4.14 × 10^-3 mbar. These samples were then annealed at 500 °C for one hour in an argon atmosphere to nucleate various nickel-silicide phases. Ion irradiation was carried out using carbon ions of energy 120 keV for two different fluences 3 × 10¹⁵ and 1 × 10¹⁶ ions per cm². Grazing Incidence X-Ray Diffraction (GIXRD), Transmission Electron Microscopy (TEM), and Rutherford Backscattering Spectroscopy (RBS) techniques were employed to characterize the resulting phases in the thin films. The findings indicate that low-energy irradiation of pre-annealed and unannealed Ni/Si bilayer samples results in significant structural modifications, which are further confirmed by TEM analysis.