Vertically aligned carbon nanotubes synthesis on nanostructured porous silicon template in short time; Raman spectroscospy and morphological study

Vertically aligned bundles of multi-walled and singled-walled carbon nanotubes were grown by modified two-stage catalytic-nanotemplate thermal chemical vapor deposition technique. This work involves nanostructured porous silicon as a template for growth of aligned carbon nanotubes. The synthesis time influences on synthesis vertically aligned carbon nanotubes (VACNT) by interaction of catalytic-nanotemplate were discussed and observed by field emission scanning electron microscope (FESEM) and micro-Raman spectroscopy. FESEM observation shows VACNT were successfully produced in short synthesis time, 15 minutes by this novel technique. Raman spectroscopy revealed the integrated intensity ratio of D- and G-peak (I_D/I_G) was less than 1, which is indicate less amorphous and defect concentration of the sample. When prolonged the synthesis time up to 60 minutes, single walled carbon nanotubes (SWCNT) were present, and the diameter of SWCNT was calculated by peak presence at low frequency radial breathing modes (RBM) and estimated around 0.5-1.3 nm. Both characterizations show carbon yield rate and quality of VACNT depend strongly on synthesis time.