Growth of carbon nanotubes on carbon/cobalt films with different sp ²/sp³ ratios

The need of barrier layer such as SiOfor carbon nanotubes (CNTs) growth limits their performance in electronic applications. In this study, conductive carbon/metal (carbon/cobalt - C:Co) composite films with the same metal content, but different sp²/sp³ ratios, were deposited using dual-source filtered cathodic vacuum arc (FCVA) technique. Three different C:Co composite films were deposited at different temperatures; visible Raman spectroscopy indicates that the sp²-rich C:Co composite film forms at high temperature (500°C), and high-resolution transmission electron microscopy (HRTEM) shows the formation of conducting graphitic-like sp ² clusters and with Co nanoclusters embedded within them. Electrical measurement shows a significant decrease in film resistivity as sp ²/sp³ ratio increases. CNTs were successfully grown on the composite films by plasma-enhanced vapor deposition (PECVD) approach. Scanning electron microscopy (SEM) shows minor effect on the density of CNTs by varying the sp²/sp³ ratio. The dependence of defect level of the as-grown CNTs is found to reduce as sp²/sp³ ratio increases.