Study on Ionized Nitrogen Implantation of Diamondlike Carbon Film

The ionized nitrogen of double-atom molecules were implanted with high-energy ion beam of (25-35) kilovolts into amorphous carbon films which were previously deposited on steel substrate by ion beam sputtering at an graphite target with low-energy between 250-500 eV. Nano-indentation results show that there is an increase in hardness from (20-30) GPa up to (27-42) GPa after ion implantation. As revealed by Raman spectroscopy, the amorphous structure of the films is unchanged after ion implantation, while those Roman parameters sensitive to bonding structure are affected, suggesting the formation of chemical bonding between nitrogen and carbon atoms. Significant chemical shift on both Cls and Nls core level peaks was found by using XPS analysis, which strongly suggests the formation of new phase after ion implantation. It can be concluded that implanting nitrogen leads to nitrogenated diamondlike carbon, changed chemical stucture and enhanced mechanical properties.