Synthesis of well-aligned carbon nanotubes on the NH3 pretreatment Ni catalyst films

Well aligned multi-walled carbon nanotubes (CNTs) have been synthesized on large area Nideposited SiO2/Si substrates via the pyrolysis of C2H2 using thermal chemical vapor deposition technique at 900°C. We concluded that NH3 pretreatment was very crucial to control the surface morphology of catalytic metals and thus to achieve the vertical alignment of CNTs. With higher density of the Ni particles, better alignment of the CNTs can be obtained due to steric hindrance effect between neighboring CNTs. The degree of crystallization of the CNTs enhanced with the increase of the NH3 pretreatment time was investigated by X-ray diffraction and transmission electron microscope studies. Energy dispersive X-ray spectrum analysis revealed that CNTs grew by a tip growth mechanism.