Amplification of photoluminescence and raman scattering in hybrid thin film structures of $a$-C:H with silver nanoparticles

In this work, we studied changes in the spectra of optical density, photoluminescence (PL) and Raman spectra of hybrid thin-film structures based on $a$-C:H and granular silver films before and after annealing of samples at 200$^{\circ}$C. The hypsochromic shift of the main plasmon peak, the formation of double resonance spectra, and an increase in the band intensity were observed after annealing of samples with the gravimetric Ag film thickness of 10 nm. The influence of both the morphology of the nanostructure of Ag films and the features of the electronic structure of $a$-C:H films were observed on the plasmon enhancement of the PL and Raman spectra. For samples based on $a$-C:H with an optical gap $E_g$ = 0.4 eV, a more effective PL enhancement was observed after annealing of the samples. At the same time, in the samples with $E_g$ = 2.7 eV, the PL intensity practically did not change, remaining higher. The amplification of resonant Raman scattering was selective. It was associated with scattering by polycyclic aromatic groups predominant in the structure of the $a$-C:H film with a narrower optical gap.