STRUCTURAL CHARACTERIZATION OF ION-IMPLANTED HOPG AND GLASS-LIKE CARBON BY LASER RAMAN-SPECTROSCOPY

A Raman spectroscopic study has been made of the surface layer structure of ion implanted carbon materials. The substrates used are two types of graphitic materials: highly oriented pyrolytic graphite (HOPG) sheets, and glass-like carbon (GLC) sheets. Argon- or nitrogen-ion implantations into the substrates were performed at an energy of 150 keV. The surface layer structure has been investigated by means of laser Raman spectroscopy. The Raman spectra for HOPG have a single peak corresponding to graphite structure, and those for GLC have two peaks corresponding to graphite and long-range disordered graphite structures. It is found that the spectra for both ion implanted HOPG and GLC consist of four principal peaks. Two well-known peaks belong to graphite and long-range disordered graphite structures. The origin of two other new peaks will be considered to be as follows: One is corresponding to an amorphous-like structure with C=C bonding, and the other is corresponding to a kind of hydrogenated-like carbon with chains of alternate C=C and C-C bonds. The ratio of the amorphous-like structure among four structures increases with the increase in the fluence or with the decrease in the target temperature during ion implantation.