Hybrid Structures of a-C:H Films Covered with Ag Nanoparticles for Application in Photonics
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ANOPHOTONICS
Hybrid Structures of a-C:H Films Covered with Ag Nanoparticles for Application in Photonics1 M. M. Abbouda, b, *, E. A. Konshinaa, c, and D. P. Shcherbinina, c a Faculty
of Photonics and Optoinformatics, ITMO University, St. Petersburg, 197101 Russia Physics Department, Faculty of Science, Mansoura University, Mansoura, 35516 Egypt c Centre of Information and Optical Technologies, ITMO University, St. Petersburg, 197101 Russia * е-mail: [email protected] b
Received January 18, 2020; revised January 18, 2020; accepted April 20, 2020
Abstract—In this paper, the optical density and photoluminescence (PL) spectra of thin-film hybrid structures based on amorphous hydrogenated carbon (a-C:H) with a wide (2.7 eV) and narrow (0.4 eV) optical gap covered with granulated silver films were studied. The main goal was to study the impact of nanostructures morphology and the thickness of granulated silver films on these hybrid structures spectra. Ag films of 2, 4, and 10 nm gravimetric thicknesses were deposited by thermal evaporation on a-C:H film surfaces previously prepared by direct current CVD. With increasing Ag film thickness, the main dipole band intensity was enhanced, and the quadrupole mode band appeared in the optical density spectra of the hybrid structures. The influence of Ag NP sizes on the quenching and enhancement of photoluminescence intensity of a-C:H films with the different optical gap was shown. Exciton–plasmon interactions in the structures with the Ag film of 10 nm thickness led to the PL intensity enhancement of the wide- and narrow-gap a-C:H films to 2 and 19 times at a wavelength of 488 nm. Nevertheless, the PL intensity of the narrow-gap film remained lower as compared to a wide-gap a-C:H film. The impact of a cross-section amplification and the Purcell effect on the PL enhancement of a-C:H in the thin-film structures as a result of localized surface plasmon resonance excitation in Ag nanoparticles are discussed. Keywords: silver nanoparticles, morphology nanostructure, amorphous hydrogenated carbon, optical density spectra, exciton–plasmon interactions, photoluminescence DOI: 10.1134/S0030400X20080020
1. INTRODUCTION Recently, localized surface plasmon resonance (LSPR) of noble metal nanoparticles (NPs), attracts a lot of interest due to widespread application in optoelectronics and sensors devices [1, 2]. The application possibility of plasmon resonance depends on wavelength, intensity and position plasmon peak, halfwidth and the structure of the absorption band in spectra [3–9]. Therefore, plasmon property variation is still a relevant issue for different applications. NP sizes, form, as well as refractive indexes of dielectric surrounding media, can change the LSPR frequency [10, 11]. Thereby, the hybrid structures of noble metals with amorphous carbon may be of practical interest. Amorphous carbon with metal nanoparticles was used as a composite electrode for supercapacitor [12], as antibacterial materials [13], in sensors [14] and UV photodetectors [15]. The application of
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