Effects of NH3 plasma pretreatment on the growth of carbon nanotubes

In CVD, it is believed that the catalyst is a crucial parameter for the diameter and the density of the CNTs. Typical thin catalyst film thickness should be less than 20 nm. While the catalyst film thickness is more than 30 nm, it is very difficult to grow thinner CNTs. Pretreatment further to break the film into desired particles should be taken. In this paper, the pretreatment effect of NH3 plasma on CNT growth was studied. Multi-wall carbon nanotubes have been grown with NH3 plasma pretreatment to the thick catalyst films by CVD. The diameter and density of CNTs changed with the plasma power and pretreatment time. The diameter of grown CNTs decreased from 10 to 4 nm as plasma intensity increased. NH3 plasma power and pretreatment time have to be optimized in order to grow uniform and density controlled nanotubes.