Optical and structural modifications of copper nanoparticles in a matrix of fullerene C60 under 220 keV Ag ion irradiation

Abstract

Metal-matrix nanocomposites have a separate variety of objectives under provisions of their enhanced properties. Ion irradiation with low energy is a curious contrivance to achieve the bulk variations of distinct materials. The effect of low energy ion irradiation is explored on Cu-C60 nanocomposite thin films grown by the thermal co-deposition method. The Cu concentration in the as-deposited sample is found to be ∼ 45 at.% by Rutherford Backscattering Spectrometry (RBS). Owing to high metal concentration, a Surface Plasmon Resonance (SPR) peak is found at 616 nm in the as-deposited sample and the average size of Cu nanoparticles is determined to be ∼7.8 nm, with a broad size distribution. The as-deposited samples are irradiated with a beam of 220 keV Ag ions using an ion accelerator, which leads to moderate variations in the structural, electrical, and optical properties of nanocomposite thin film. The SPR peak is effectively red-shifted by ∼16 nm at a highest dose. The outcomes of Raman spectroscopy disclose the gradual transformation of fullerene C60 into amorphous carbon with increasing doses. High-Resolution Transmission Electron Microscopy (HRTEM) images demonstrate the minor growth of copper nanoparticles with ion irradiation. A growth in surface grains with ion dose is confirmed by Field Emission Scanning Electron Microscope (FESEM) and Atomic Force Microscopy (AFM). The X-ray Photoelectron Spectroscopy (XPS) measurements have been used for the chemical state evaluation of the nanocomposite films. The I-V measurements show the conversion of fullerene into amorphous carbon with a loss in the resistivity of the film.

Keywords

• Surface plasmon resonance (SPR)
• Nanocomposite thin film
• Ion irradiation
• Copper-fullerene