Patterned growth of carbon nanotubes synthesized by Fe-catalyzed chemical vapour deposition

A key requirement in the carbon nanotubes (CNTs) technology is to develop a method able to produce well positioned structures of nanotubes with uniform and reproducible properties, simple to integrate within the manufacturing process of electronic devices. The catalytic chemical vapor deposition (CCVD) of carbon nanotubes is a fully compatible technique with the ultra large scale integration process of the microelectronic industry. For this reason we have developed site-selective CCVD synthesis on substrates where patterned islands of catalyst are formed. This type of deposition process has been proved to grow nanotubes at controllable locations. Several types of substrates used in the microelectronic industry, such as silicon, silicon oxide and porous silicon have been considered. On these substrates metallic iron in the form nanoparticles was used as a catalyst and the nanoparticles have been investigated as seeds to nucleate the growth of the nanotubes. Various CVD process parameters, such as the carbon gas precursor type and the percentage in the gas mixture, use of carrier gases in the gas mixture and deposition temperature, have been investigated to obtain patterned arrays of nanotubes. In this paper we present the relevant findings we obtained for the patterned growth of CNTs on different substrates by using evaporated iron as a catalyst.