Effect of deposition time on surface plasmon resonance and Maxwell-Garnett absorption in RF-magnetron sputtered carbon-nickel films

In this work, carbon-nickel films were grown during four deposition times (50 s, 90 s, 180 s and 600 s) at room temperature on glass substrates by radio frequency magnetron sputtering. The optical absorption spectra of the films were investigated with a special emphasis on the surface plasmon resonance (SPR) of Ni nanoparticles. The optical absorption peaks caused by the surface plasmon resonance of Ni nanoparticles were observed in the wavelength range of 300 nm to 330 nm. It has been shown that the surface plasmon resonance peaks exhibit a red shift and a blue shift depending on the deposition time. The red and blue shifts of the surface plasmon resonance in the absorption spectra of the films were observed with the increase and decrease of Ni nanoparticle size, respectively. The Ni nanoparticle size, dielectric function of carbon matrix ε_m and plasma frequency of free electrons ωp for the films deposited at deposition time of 180 s have maximum values of 80 nm, 0.401 and 7.25 × 10¹⁵ s^–1, respectively. These observations are in a good agreement with the electrical resistivity measurements and Maxwell-Garnett (M-G) effective medium theory (EMT).