To create conductive and wear-durable carbon thin films using metal doping, we deposited Co-doped and Ni-doped carbon thin films onto silicon substrates by RF sputtering. Then we evaluated the dopant concentrations, resistivity, scratch hardness, carbon sp2 and sp3 bonding fractions, and the microscopic structure of the films. The resistivity of the Co-doped film remarkably decreased compared to that of non-doped carbon film when the dopant concentration was 1 at.% and it slightly decreased when the dopant concentration increased. The Ni-doped film resistivity decreased when the dopant concentration increased. The scratch hardness of the Co-doped and Ni-doped films was approximately equal to that of the non-doped film when the metal concentrations of the films were less than 6 and 5 at.%, respectively. The scratch hardness of the Co-doped film was degraded slightly as the dopant concentration became greater than 7 at.%. However, the scratch hardness of the Ni-doped film was significantly degraded when the dopant concentration was greater than 7 at.%. The Co-doped film with dopant concentration less than 12 at.% was most suitable from a practical perspective because of its low resistivity and high scratch hardness.
The combination of ultraviolet (UV) irradiation and hydrogen peroxide (H2O2) treatment is proposed for environmentally benefical oxidation of carbon nanotubes. After 144 hours of treatment, TEM observation reveals that carbon nanotubes show clear structural changes. This treatment produces structural changes of carbon nanotubes at room temperature.