Effects of temperature and catalysts on the synthesis of carbon nanotubes by chemical vapor deposition

Abstract

Carbon nanotubes were produced on a quartz plate and a silicon wafer by chemical vapor deposition using xylene as a carbon resource, iron and cobalt as catalysts, and ammonia as a reactive gas. A series of experiments was carried out to investigate the effects of reaction temperature, substrates, and catalysts on the synthesis of the nanotubes. The TEM analyses revealed that the nanotubes had a typical bamboo-shaped inner layer structure. Ammonia gas was found to have played a very important role in producing such bamboo-shaped CNTs by easing the formation of the graphite layers due to the catalyst activator and amorphous carbon reducer. The growth of CNTs was affected by the thickness of the silicon oxide layer. With iron catalysts, the growth of CNTs increased with an increase in the thickness of the silicon oxide layer. However, an opposite phenomenon occurred with the use of cobalt catalysts.