Growth and characterisation of carbon nanostructures obtained by MPACVD system using CH4/CO2 gas mixture

In this study. CH4/CO2 gas mixture in Microwave Plasma Assisted Chemical Vapour Deposition (MPACVD) system is used for the growth of different Carbon Nanostructures (CNSs). Fe-SiO deposited on Si(100) in which Fe particles are embedded in a 50 nm SiO film were used as the catalyst. By varying the amount of CH4 to CO2, We have observed that it is possible to obtain a variety of CNSs including Carbon Nanotips (CNTPs) at 45% of CH4, bundle of Multi-wall Carbon Nanotubes (MWCNTs) at 48-50% of CH4, and Carbon Nanowalls (CNWs) at 53% of CH4 at a temperature around 900 degrees C. The diagnostic of the used plasma discharge is carried out by optical emission spectroscopy (OES). It shows the presence of atomic hydrogen H, CH, C-2, CO and OH radicals. Scanning electron microscopy observations show that the obtained CNTPs are not perpendicular to the surface, due to the no applied polarisation to the substrate holder during the growth. The top of the CNTPs size and length are respectively around 10 nm and 3 pm. Raman spectroscopy measurements exhibit a variation in the D and G lines intensity when varying the CH4 amount in the gas mixture. Correlations between OES characterisations and microstructural analyses are established. (c) 2005 Elsevier B.V. All rights reserved.