Carbon onions formation by high-dose carbon ion implantation into copper and silver

High-fluence (>1016 cm−2) ion implantations of 120-keV carbon ions have been performed at elevated temperature (≥400°C) into metals (Ag, Cu) in which carbon is almost immiscible. The different carbon structures so synthesized have been characterized by transmission electron microscopy and atomic force microscopy. It mainly results in the formation of numerous carbon onions composed of concentric graphitic layers. We will show that pure carbon onion layers can even be obtained by carbon ion implantation into a silver thin film deposited onto silica. Furthermore, we discuss the potential of the technique in adjusting the size and controlling the microstructure of the carbon onions by varying implantation parameters such as temperature and fluence. We also briefly discuss the nucleation and growth mechanisms of the carbon onions during the ion implantation process.