E?ect of Growth Parameters on Morphology of Vertically Aligned Carbon Nanotubes

Vertically aligned carbon nanotubes (CNTs) were synthesized on Fe-deposited silicon substrates using chemical vapor deposition. Scanning electron microscope investigations reveal that the morphology of the CNTs depends on several growth parameters including the reaction temperature, the size of catalyst nanoparticles, and the partial pressure of the reaction gas. When the reaction temperature rises or the concentration of carbon source gas increases, the diameter of CNTs gets larger, but the length becomes shorter. With decreasing thickness of the catalyst film, the diameter of the CNTs shrinks monotonically, but the length of the CNTs increases first, reaches a maximum and then decreases afterwards. These results indicate that the diameter and the length of the vertically aligned CNTs can be manipulated by selecting appropriate growth parameters.