An atomic-scale analysis of catalytically-assisted chemical vapor deposition of carbon nanotubes

Growth of carbon nanotubes during transition-metal particles catalytically-assisted thermal decomposition (also referred to as chemical vapor deposition or CVD) of methane in hydrogen as a carrier gas has been analyzed at the atomic scale using a kinetic Monte Carlo method. The method is parameterized by the rates of various nanotube surface and edge reactions (e.g. adsorption of hydrocarbons and hydrogen onto the surface of the transition-metal particles and onto the surface of carbon nanotubes, carbon atom attachment to the growing end of nanotubes, nucleation and growth of the outer nanotubes walls, etc.). Simulations of the carbon nanotubes growth are found to yield predictions regarding the effect of nominal and local processing conditions on the nanotubes morphology and growth rates in very good (qualitative and quantitative) agreement with their experimental counterparts. In addition, formation of new walls during growth is found to take place quite readily suggesting that the fabrication of single walled carbon nanotubes by CVD may be a formidable task.