Amorphous carbon (a-C) thin films are synthesized using a nonequilibrium method of ion-plasma sputtering of a graphite target under argon atmosphere at a constant plasma current. The local...

As nanotechnology continues to advance, the study of nanocomposites and their unique properties is at the forefront of research. There are still various blank spots in understanding the behavior of such composite materials, especially regarding plasmonic effects like localized surface plasmon resonance (LSPR) which is essential for developing advanced nanotechnologies. In this work, we explore the structural properties of composite thin films consisting of oxide matrices and gold nanoparticles (Au NPs), which were prepared by radio-frequency magnetron sputtering. Titanium dioxide (TiO₂) and tungsten trioxide (WO₃) were chosen as the host matrices of the composites. Such composite thin films owing to the presence of Au NPs demonstrate the LSPR phenomenon in the visible region. It is shown, that spectroscopic study, in particular, Raman spectroscopy can reveal peculiar features of structures of such composite systems due to LSPR and photoluminescence (PL) of Au NPs in the visible spectrum. In particular, defect peaks of TiO₂ (700–720 cm⁻¹) or WO₃ (935 cm⁻¹) in Raman spectra can be clearly observed when the samples are illuminated with a 633 nm excitation laser. Excitation with 532 nm leads to a decrease in the intensity of the defect peak, which totally disappears at 473 nm excitation. Such dependences of the defect peaks on excitation laser wavelength are probably related to the polarization of the matrix’s defective regions close to the interface with gold NPs.

The structure and phase composition of thin a-C:H and a-C:H〈M〉 films (M = Ag, Ti, or Ag + Ti) have been studied by Raman and X-ray photoelectron spectroscopy. The a-C:H〈M〉 films were prepared by ion-plasma magnetron sputtering of a combined target of graphite and metal in an Ar–CH₄ gas mixture. The Raman spectra of these films indicate that their structure is amorphous. The a-C:H〈Ag + Ti〉 films have a more graphitized structure in comparison with pure a-C:H films and films containing only one metal. It is established that carbon in the a-C:H〈Ag + Ti〉 films is in the sp², sp³, and C=O states, which are characteristic of the a-C:H, a-C:H〈Ag〉, and a-C:H〈Ti〉 films. In addition, there are also ether (–C–O–C–) or epoxy (‒C‒O–) carbon groups in the a-C:H〈Ag + Ti〉 films. It has been revealed that silver atoms in the a-C:H〈Ag〉 and a-C:H〈Ag + Ti〉 films form no chemical bonds with carbon, oxygen, and titanium. Titanium in the a-C:H〈Ti〉 and a-C:H〈Ag + Ti〉 films exists in the form of titanium IV oxide (TiO₂).

Ion plasma sputtering, carbon diamond-like films, modification, metal nanoclusters, optical properties, plasmon resonance.