Diffusion effect for the catalytic growth of carbon nanotubes on metal alloys substrate

Multiwall carbon nanotube (MWCNT) films were synthesized on a metal-alloy probe using thermal chemical vapor deposition (CVD) at low temperature (550 degrees C). The morphology of the Ni catalyst deposited on Co and Ta barrier layers on the metal-alloy substrate was investigated. In addition, we studied the tuning of the thickness of the Ni catalyst (without Co and Ta barrier layers), pretreatment time in a NH3, and the C2H2/NH3 ratio for growing MWCNTs. We showed that buffer layers were unstable during Ni catalyst nucleation on the metal-alloy probe during CNT growth because it diffused into the surface of probe and recrystallized during pretreatment. The results suggest that only using a thicker Ni catalytic layer (50 nm) could it allow for the growth of MWCNTs on the metal-alloy probe. The length of the MWCNTs was similar to 10 mu m. In this paper, we propose a mechanism for thermal CVD of MWCNTs on a metal-alloy probe without barrier layers under a C2H2/NH3 atmosphere.