Influence of Ni Catalyst Layer and TiN Diffusion Barrier on Carbon Nanotube Growth Rate

• Published in: Nanoscale research letters 2010-03, Vol.5 (3), p.539-544
• Main Authors: Kpetsu, Jean-Baptiste A, Jedrzejowski, Pawel, Côté, Claude, Sarkissian, Andranik, Mérel, Philippe, Laou, Philips, Paradis, Suzanne, Désilets, Sylvain, Liu, Hao, Sun, Xueliang
• Format: Article
• Language: English
• Subjects: Chemistry and Materials Science; Materials Science; Molecular Medicine; Nanochemistry; Nanoscale Science and Technology; Nanoscale science and technology for electronics; Nanotechnology; Nanotechnology and Microengineering; photonics and renewable energy applications: Selected papers from NGC2009 & CSTC2009 conference; Special Issue; Special Issue Article
• ISSN: 1931-7573; 1556-276X
• DOI: 10.1007/s11671-010-9544-y

Dense, vertically aligned multiwall carbon nanotubes were synthesized on TiN electrode layers for infrared sensing applications. Microwave plasma-enhanced chemical vapor deposition and Ni catalyst were used for the nanotubes synthesis. The resultant nanotubes were characterized by SEM, AFM, and TEM. Since the length of the nanotubes influences sensor characteristics, we study in details the effects of changing Ni and TiN thickness on the physical properties of the nanotubes. In this paper, we report the observation of a threshold Ni thickness of about 4 nm, when the average CNT growth rate switches from an increasing to a decreasing function of increasing Ni thickness, for a process temperature of 700°C. This behavior is likely related to a transition in the growth mode from a predominantly “base growth” to that of a “tip growth.” For Ni layer greater than 9 nm the growth rate, as well as the CNT diameter, variations become insignificant. We have also observed that a TiN barrier layer appears to favor the growth of thinner CNTs compared to a SiO 2 layer.