Abstract
A single-walled carbon nanotube (SWNT) is a graphene layer rolled up into a cylinder, with its end cap structure similar to the half of C60. Depending on their (m, n) indices, SWNTs have different electrical properties. SWNTs can be metallic, semiconducting or small-gap semiconducting, depending on their structure and diameters. So control of the diameter of single-walled carbon nanotubes becomes the challenge of developing SWNTs-based nanoelectronic devices. A reliable method of controlling the diameter distribution of single-walled carbon nanotubes is needed. In this thesis, we presented a study of synthesizing high quality SWNTs with narrow diameter distribution by optimizing the Mo/Fe/Al/SiO2 catalytic system in thermal CVD. It was found that thickness of Al layer had significant effects on the quality of SWNTs. A high quality, almost bundle-free, SWNTs with G/D area ratio of 45 was obtained by optimizing the catalytic system with Mo(0.5nm)/Fe(1nm)/Al(5nm)/SiO2(100nm) multi-layer catalyst and the CVD growth process parameters. A narrow diameter distribution of 0.8~1.4 nm (mostly ~1.2 nm) was achieved. Finally, we summarized these results by proposing a SWNTs growth mechanism with multi-layer catalytic system to explain the effects of varying the thickness of each layer.