Towards Type-Selective Carbon Nanotube

7 Carbon nanotubes have been intensively researched for electronic applications, driven 8 by their excellent electronic properties, with the goals being control and 9 reproducibility of growth, semiconducting/metallic type selectivity and maintaining 10 high quality of carbon nanotubes, in a process that is temperature-compatible with the 11 electronics. Photo-thermal chemical vapour deposition can achieve these goals and, 12 through a thorough investigation of the parameter space, we achieve very high 13 nanotube-quality and growth rates, and produce a phase-diagram that reveals distinct 14 regions for growing semiconducting and metallic single-walled nanotubes, as well as 15 multi-walled ones. Correlation with the carbon-catalyst phase diagram allows for the 16 development of a novel growth model. We propose that the temperature-gradient 17 induces carbon diffusivity-gradient across the catalyst to yield the high growth rate. 18 This is attributed to the increase of α-iron of catalyst. The growth control 19 demonstrated here allows for integration of the nanotube growth process by 20 photo-thermal deposition into mainstream electronics manufacture. 21 ____________________________________________________________________ 22