Growth Kinetics in a Large-Bore Vertically Aligned Carbon Nanotube Film Deposition Process

Abstract

Vertically aligned films of multiwalled carbon nanotubes (VACNT) are synthesized in a large-bore chemical vapor deposition reactor by employing a Cr−Ni−Fe thin film catalyst stack predeposited on substrates. The kinetics of the growth process is studied by measuring the VACNT film thickness, the resistivity (indicative of the density), and the distribution of carbon nanotube (CNT) diameters as a function of pregrowth catalyst treatment time, growth time, and growth temperature. It is found that pregrowth treatment times of about 210 min are needed before reaching steady-state catalyst conditions. Shorter pregrowth treatment times produce a thicker but less dense film. The CNT diameters are only weakly affected by the pregrowth treatment time (for at least greater than 30 min.). A model is proposed to explain these results. The kinetics of the film growth are studied as a function of growth time and temperature under steady-state catalyst conditions. The CNT film thickness is well fit by the kinetic model ...