High Growth Yield of Single Multiwall Carbon Nanotube With Different Length Effect

Vertically aligned single multiwalled carbon nanotube (MWCNT) is quite an interesting nanostructure due to its high probability of nanodevice realization with an ultrahigh integration density. Although ~200 nm catalyst diameter size and plasma-enhanced chemical vapor deposition (PECVD) method have been known as key parameters to grow a single MWCNT, the details and the phenomenon of below 200 nm catalyst size have not been studied or published well. Here, we report the details of catalyst size effect below 200 nm. One-hundred-nanometer diameter Ni catalyst on SiO₂ layer shows 95% yield of single MWCNT growth. Surface roughness of substrate makes a large deviation in the yield and the critical catalyst size for single MWCNT. The various catalyst sizes result in the different growth rate of carbon nanotube (CNT) at the same growth condition. The change of diffusion surface area induces such a difference. From the results, single MWCNTs with various lengths are successfully grown on the same substrate by a one-step growth process.