Experimental study of microwave assisted CVD growth of carbon nanotubes on silicon wafer using cobalt as a catalyst

Controlled growth of carbon nanotubes is an important step in the realization of practical nanoscale devices for applications in nanoelectronics, sensors, field emission displays, and microelectro mechanical systems (MEMS), among others. Microwave assisted Chemical Vapor Deposition (CVD) technique has been successfully used to synthesize carbon nanotubes on silicon wafer substrates. Since a transition metal catalyst, such as iron, nickel, cobalt is needed for growth of nanotubes, a thin film of cobalt catalyst (2∼5 nm) is deposited on the silicon wafer substrates using Pulsed Laser Deposition (PLD) technique using an excimer laser (248nm). The CVD process conditions, including growth time, plasma pretreatment time, process gases, and flow rate of carbon source gas (methane) are studied towards obtaining controlled growth of nanotubes. Further, patterned catalyst film is formed by the PLD technique and vertically aligned nanotubes are successfully grown on patterned catalyst film. The carbon nanotubes are characterized using SEM, TEM, AFM and mu-Raman Spectroscopy.