Structure of the silver containing diamond like carbon films: Study by multiwavelength Raman spectroscopy and XRD

Abstract

In the present study structure of silver containing diamond like carbon (DLC:Ag) films deposited by reactive magnetron sputtering was investigated by X-ray diffractometry (XRD) and multiwavelength Raman spectroscopy. In the case of the DLC:Ag films containing low amount of silver, crystalline silver oxide prevails over silver. While at higher Ag atomic concentrations formation of the silver crystallites of the different orientations was observed. Surface enhanced Raman scattering (SERS) effect was detected for high Ag content in the films. For UV excited Raman spectra sp3 bonded carbon related Raman scattering T peak at ~1060cm−1 was detected only for the films with the highest amount of silver (34.3at.%). The dependence of the Raman scattering spectra parameters such as position of the G peak, G peak full width at half maximum (FWHM(G)), D/G peak area ratio on Ag atomic concentration in DLC:Ag film as well as Raman scattering spectra excitation wavelength were studied. The dependence on Ag amount in film was more pronounced in the case of the Raman scattering spectra excited by higher wavelength laser beam, while in the case of the spectra excited by 325nm and 442nm laser beams only weak dependence (or no dependence) was observed. Overall tendency of the decrease of the dispersion of the G peak with the increase of Ag atomic concentration was found. Thus sp3/sp2 bond ratio in DLC:Ag film decreased with the increase of Ag atomic concentration in the films.