Bias polarity effect on the growth of CNTs by a triode DC-PECVD

We report on the growth mechanism of vertically aligned carbon nanotubes (VACNTs) by using a triode-type direct current (dc) plasma enhanced chemical vapor deposition (PECVD) system. The deposition system was designed to impose bias on a mesh located between power and ground electrodes. The CNTs grown with 300 V biased to the mesh grid have a diameter of ∼ 85 nm and a height of ∼ 250 nm. However, the diameter and height of the ONT are ∼ 20 nm and ∼ 5 μm, respectively, when the grid is biased with -300 V. The density and diameter of CNTs can be controlled by the mesh bias, which is due to the ion bombardment.