Rapid Acetylene and Water Vapor Cycling for Length-Controlled Layered Growth of Vertically Aligned Single-walled Carbon Nanotubes
C.L. Pint, A.N.G. Parra-Vasquez, N. Alvarez, M. Pasquali, R.H. Hauge
Rice University, US
Keywords: carpets, carbon nanotubes, chemical vapor deposition
Abstract:A technique is developed in which layers of vertically aligned single-walled carbon nanotubes (SWNT) are grown by rapid cycling of reaction gases in a hot filament chemical vapor deposition apparatus. Based on an alternating C2H2 growth and H2/H2O etch cycle in a rapid switching gas valve system, we demonstrate the ability to grow SWNT having well-defined lengths dependent on the duration of a C2H2 pulse to the catalyst surface. Detailed analysis confirms the detachment of subsequent layers, making this a highly efficient and simple technique to achieve length control in the growth of SWNT. In addition, this technique gives us an in-situ measurement of growth, allowing us to study the different factors, such as gas diffusion and dynamic catalyst behavior, which may result in the decrease in growth rate as well as growth termination.