Diameter Selective Growth of Vertically Aligned Single Walled Carbon Nanotubes and Study on Their Growth Mechanism

Diameter controlled vertically aligned single walled carbon nanotubes (VA-SWNTs) were synthesized by controlling flow rate of carbon source and dimension of catalyst nanoparticles. The large scale structural analysis demonstrating spatial distribution of SWNT diameters was conducted by a newly developed Raman Radial Breathing Mode (RBM) mapping technique. Also we investigated the fundamental mechanism of diameter selective growth of SWNTs during the CVD process through computational modeling. Our experimental and computational studies show that a lower flow rate of carbon source makes a smaller nucleation site for a SWNT resulting in a smaller diameter formation. On the other hand, a higher flow rate of carbon source forms a larger nucleation site growing a SWNT with the larger diameter.