A comprehensive multiphysics, multiphase model of carbon nanotube (CNT) fabrication process by chemical vapor deposition (CVD) is utilized to study the effects of several physical phenomena inside the quartz tube. The investigations include fluid flow properties, temperature profile and heat transfer as well as diffusion and concentration of carbon species along the substrate. These properties are examined in a great detail for a horizontally placed substrate. For each physical property, the effects of substrate dislocation as well as the angle between substrate and reactor chamber longitudinal axis are investigated. It is shown that the temperature in the gas phase reactions region is significantly lower compared to the temperature profile around the substrate. Based on the obtained results, two new CVD system designs are proposed to enhance the temperature in the reactor chamber section where gas phase reactions take place. Moreover, it is shown that substrate dislocation and angle change result in physical property change such as species concentration on upper and lower substrate surfaces. This study is also applicable to other CVD-based fabrication process such as deposition of any layer, since the methodology of the fabrication process remains the same.
Carbon nanotube synthesis via the catalytic chemical vapor deposition of methane in the presence of iron, molybdenum, and iron–molybdenum alloy thin layer catalysts
