Field emission characteristics of multiwalled carbon nanotubes grown at low temperatures using electron cyclotron resonance chemical vapor deposition

Vertically aligned multiwalled carbon nanotubes were synthesized by electron cyclotron resonance chemical vapor deposition on Ni-coated glass substrates at temperatures as low as 400 °C. Negative self-biases were induced to the substrates by radio frequency plasma to give ion bombardment to the growing surface. An increase of self-bias voltages from 250 to 2200 V resulted in an evolution of the microstructures from amorphous carbon to nanorods, subsequently to nanotubes. Nanotubes grown above 2150 V were more straight in morphology and better in crystallinity than nanorods grown at 2100 V. In the field emission ~FE! measurements, the electric fields to obtain 1 mA/cm were 4.6 and 11.1 V/mm for the nanorods and nanotubes grown at 2100 and 2200 V, respectively. The emission areas, calculated from the Fowler–Nordheim plots, were much larger in the nanorods than the nanotubes. It is considered that a larger amount of crystalline defects in nanorods plays a major role in improving their FE characteristics. © 2003 American Vacuum Society. @DOI: 10.1116/1.1580116#