Controlled nanostructuration of catalyst particles for carbon nanotubes growth

We report on a novel method based on a plasma pre-treatment for controlled nanostructuration and patterning of iron catalyst particles from a continuous film in view of carbon nanotube growth. The effects of the hydrogen plasma conditions on the diameter and the density of the catalyst nanoparticles was studied and discussed. We were then able to propose a comprehensive mechanism for the metallic nanostructuration. We showed that as the plasma power density increases, first a reduction of the iron nanoparticle size is observed followed by for the highest plasma powers a phenomenon of alteration in the deposited film. A better control of the nucleation process and the nanostructuration were observed for low hydrogen pressures. The correlation between the plasma parameters and the obtained iron nanoparticles was established. The growth of carbon nanotubes (CNTs) was carried out on the patterned catalyst nanoparticles under CH4/H2 microwave plasma. High quality double-walled and multi-walled CNTs of a diameter of about 5 nm have be obtained.