Synthesis and characterization of Cu-C60 plasmonic nanocomposite

Plasmonic nanocomposite thin film containing Cu metal nanoparticles in fullerene C60 matrix is developed by thermal co-evaporation method on glass substrate. In order to excite the surface plasmon resonance (SPR), thermal annealing is performed from 100 °C to 400 °C on as-deposited thin film in an inert atmosphere (continuous flow of Ar gas) for 30 min. SPR is successfully generated at ∼694 nm for the film annealed at a temperature of 300 °C which is further blue shifted at ∼684 nm at a temperature of 400 °C. The film thickness and Cu metal atomic concentration is found to be ∼70 nm and ∼27 at.%, respectively using Rutherford Backscattering Spectroscopy. Raman spectroscopy is used to identify the structural changes occurring in fullerene C60 matrix with thermal annealing. The transformation of fullerene C60 into amorphous carbon is observed with increasing temperature. Transmission electron microscopy is used to confirm the growth of Cu nanoparticles with increasing temperature and particle size is found to be 27.9 nm for the film annealed at 400 °C. The modifications in surface morphology of annealed samples are studied by field emission electron microscope (FE-SEM) and atomic force microscope (AFM). The absence of Copper oxide in the annealed samples is confirmed by X-ray photoelectron spectroscopy. Current vs. voltage measurements are performed to quantify the increased conductivity of annealed samples.