Early stages of the carbon nanotube growth by low pressure CVD and PE-CVD

The early stages of single-walled (SWCNT) and multi-walled carbon nanotube (MWCNT) growth were investigated by chemical vapour deposition (CVD) and plasma enhanced CVD (PE-CVD). SWCNT and MWCNT nuclei were observed using low pressure and short duration synthesis process. Microscopic evidences of the quite long duration, and hence complexity, of the MWCNT nucleation compared to SWCNT growth was provided. Besides, Raman spectroscopy pointed out significant differences in terms of disorder between the CVD and PE-CVD samples at the early stage of the growth process. The CVD process was found to be more selective for carbon nanotube growth, without significant disordered carbon material deposited on the substrate.