Enhancement of Photoluminescence and Raman Scattering in Hybrid Thin-Film Structures of a-C:H with Silver Nanoparticles

The changes occurring in the optical density, photoluminescence (PL), and Raman scattering (RS) spectra of thin-film structures based on a-C:H and granulated silver films after annealing of samples at 200°C are studied. A hypsochromic shift of the main plasmon peak, formation of double resonance spectra, and an increase in band intensities were observed after annealing of samples with a 10-nm gravimetric thickness of the Ag film. It is shown that both the Ag film nanostructure morphology and the a-C:H film electronic structure affect the plasmon enhancement of PL and Raman spectra. A more efficient PL enhancement was observed after annealing of samples based on a-C:H with optical band gap Eg = 0.4 eV. At the same time, the initially higher PL intensity of samples with Eg = 2.7 eV almost did not change. The enhancement of resonance RS had a selective character. It was related to scattering by polycyclic aromatic groups, which are dominant in the structure of the a-C:H film with a narrower optical band gap.