Characterization of carbon nanotubes grown by chemical vapour deposition

Abstract

Carbon nanotubes (CNTs), discovered by Ijima in 1991, are one of the allotropes of carbon, and can be described as cylinders of graphene sheet capped by hemifullerenes. CNTs have excellent electrical, mechanical, thermal and optical properties and very small size. Due to their unique properties and small size, CNTs have a great potential for use in electronics, medical applications, field emission devices (displays,scanning and electronprobes/microscopes) and reinforced composites. CNTs can be grown by different methods from a number of carbon sources such as graphite, CO,C2H4, CH4 and camphor. Under certain conditions, a metallic catalyst is used to initiate the growth. The three main methods used to grow CNTs are: Arc-discharge, laser ablation (LA) and chemical vapour deposition (CVD). In the present work CNTs were grown from a mixture of camphor (C10H16O) and ferrocene (C10H10Fe) using Chemical Vapour Deposition (CVD) and argon was used as a carrier gas. The iron particles from ferrocene acted as catalysts for growth. The substrates used for the growth of CNTs were crystalline Si and SiO2 (Quartz) placed in a quartz tube in a horizontal furnace. Several parameters have been found to affect the CNT growth process. The effects of three parameters: growth temperature, carrier gas (Ar) flow rate and catalyst concentration were investigated in the present work in order to optimize the growth conditions with a simple and economical CVD setup. The samples were characterized using electron microscopy (EM), thermogravimetirc analysis (TGA), Raman and FTIR spectroscopy techniques. It was found that the quality and yield of the CNTs were best at 800°C growth temperature, 80sccm flow rate and 4% catalyst concentration.