Hybrid nanostructures of plasmonic gold nanoparticles with a-C:H thin films

Abstract

Localized surface plasmon resonance (LSPR) of gold nanoparticles (Au NPs) in a granulated film with thickness 2 nm was investigated at the interface of two amorphous hydrogenated carbon (a-C:H) films with optical gap 0.67 eV and 2.7 eV. In these hybrid structures, a blue shift of the LSPR wavelength was observed in contrast with Au NPs on quartz surface at a room temperature. The annealing of such hybrid structures at 200 °C resulted in forming spheroid Au NPs with the dimensions about 11 nm which promotes increasing blue shift of the LSPR spectra. The intensity of the LSPR peak increased significantly after annealing at 300 °C, but Au NPs film morphology and LSPR peak position have not changed. After annealing at 400 °C the LSPR peak intensity in hybrid structure with a narrow gap a-C:H film decreased dramatically but did not change in the sample with a wide gap a-C:H. The observed changes in the LSPR spectra as a result of hybrid structures annealing are associated with the difference in the electronic and atomic structure of a-C:H thin films, as shown by their studies using Raman spectroscopy.