Long, Vertically Aligned Single-Walled Carbon Nanotubes from Plasmas: Morpho-Kinetic and Alignment Controls

Abstract

The enhanced large‐scale model and numerical simulations are used to clarify the growth mechanism and the differences between the plasma‐ and neutral gas‐grown carbon nanotubes, and to reveal the underlying physics and the key growth parameters. The results show that the nanotubes grown by plasma can be longer due to the effects of hydrocarbon ions with velocities aligned with the nanotubes. We show that the low‐temperature growth is possible when the hydrocarbon ion flux dominates over fluxes of other species. We have also analysed the dependencies of the nanotube growth rates on nanotube and process parameters. The results are verified by a direct comparison with the experimental data. The model is generic and can be used for other types of carbon nanostructures such as carbon nanowalls, vertical graphenes, etc.

Theoretical modeling of temperature dependent catalyst-assisted growth of conical carbon nanotube tip by plasma enhanced chemical vapor deposition process

“…More recently, Burmaka et al 15 have shown that the growth rates of SWCNT array and the film between the nanotubes, as well as the length of SWCNTs can be successfully controlled by adjusting neutral and ion fluxes to the nanotubes, SWCNT surface temperature and the penetration depths of the neutral and ionic species.…”

“…Numerous works have been done to highlights the role of temperature on the growth of CNTs. [8][9][10][11][12][13][14][15] Han et al 8 have demonstrated that as the growth temperature increases, the average diameter of CNTs increased from 40 to 110 nm and the growth rate was enhanced from 2 to 15 lm/h. Baratunde et al 9 have shown that as the growth temperature was decreased, the associated decrease in CNT density and average CNT diameter resulted in an increased thermal resistance at the interface.…”

“…[12][13][14][15] Denysenko et al 12 have studied the growth of single walled CNTs (SWCNTs) in a PECVD using the surface deposition model. In this case, it was shown that at low substrate temperatures (1000 K), the atomic hydrogen and ion fluxes from the plasma could strongly affect the nanotube growth.…”

Graphene–CNT hybrids by thermal and plasma‐enhanced chemical vapor deposition process: Numerical modeling of growth and energy kinetics

“…Of the known techniques to grow carbon nanostructures, CVD in a plasma medium is prominent owing to the low‐temperature growth of nanostructures, good control over the morphology, and process parameters . In a plasma‐enhanced CVD (PECVD) process, the energetic electrons in the plasma enhance the ionization, excitation, and dissociation of hydrocarbon precursors at relatively low temperature .…”

“…The nanostructure growth characteristics can be controlled by the proper selection of the plasma parameters. Studies have been carried out to investigate the effect of radiofrequency power, feedstock gas ratio, hydrogen gas, and growth time, and so forth on the structure, growth rate, and dimensions of the CNT and graphene …”