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

High-fluence (> 10(16) cm(-2)) ion implantations of 120-keV carbon ions hav e been performed at elevated temperature (greater than or equal to 400 degr ees C) into metals (Ag, Cu) in which carbon is almost immiscible. The diffe rent carbon structures so synthesized have been characterized by transmissi on electron microscopy and atomic force microscopy. It mainly results in th e formation of numerous carbon onions composed of concentric graphitic laye rs. We will show that pure carbon onion layers can even be obtained by carb on ion implantation into a silver thin film deposited onto silica. Furtherm ore, we discuss the potential of the technique in adjusting the size and co ntrolling the microstructure of the carbon onions by varying implantation p arameters such as temperature and fluence. We also briefly discuss the nucl eation and growth mechanisms of the carbon onions during the ion implantati on process. (C) 2000 Elsevier Science S.A. All rights reserved.