Growth of single-walled carbon nanotubes from hot-implantation-formed catalytic Fe nanoparticles assisted by microwave plasma

We have investigated a fabrication of carbon nanotubes (CNTs) from Fe nano-size clusters formed near the surface of the thermally grown SiO2 layer on the Si substrates using Fe+ implantation at the substrate temperatures of 600 and 1000 °C. In the present study, we have found that the cluster size formed by the 600 °C-implantation is significantly uniform with the mean diameter and standard deviation of 2.6 and 0.6 nm, respectively. In contrast, the diameter distribution for the 1000 °C-implanted sample was slightly deviated, taking the values of 3–13 nm. The cluster size mainly depends on the substrate temperature during the implantation. We have confirmed single-walled CNTs grown from the Fe nanoparticles formed near the surface region in the SiO2 layer, via clearly observed peaks for the radial-breathing-mode in Raman spectra. We have also investigated the growth mechanism of the CNTs in terms of the plasma and surface interactions during microwave-plasma-enhanced chemical vapor deposition (MPCVD). It should be emphasized that the ion implantation technique combined with the MPCVD method is a powerful tool for in situ growth of SWCNT directly on a SiO2 layer or Si substrate.