Characteristics of carbonaceous materials with nanotubes grown by hot-filament plasma-enhanced chemical vapor deposition method

We have grown carbonaceous materials with nanotubes (CNTs) using a HFPECVD (hot-filament plasma-enhanced chemical vapor deposition) method for the purpose of finding their growth characteristics according to the growth conditions and angles between substrate and cathode. C2H2 gas was used as the carbon precursor and NH3 gas used as the dilution gas. SEM images of Ni-catalyst layers pretreated with NH3 plasma show that nano-size grains were formed, and the diameter as well as the density of CNTs depended on the pretreatment of the catalytic layer. The characteristics of CNTs were supposed to have some relationship with the angle (theta) between substrate and cathode. Raman spectra showed both D-band and G-band peaks around 1360 cm(-1) and 1598 cm(-1) respectively, and the position of these two peaks was not changed with both plasma bias and temperature. However, I-G/I-D, relative intensity ratio decreased with the substrate angle (theta), which indicates that the amounts of amorphous carbon and defective structure in CNTs increased. TEM image showed that CNTs synthesized in this work had multiwall structure and hollow in their body. (c) 2005 Elsevier B.V. All rights reserved.