Towards type-selective carbon nanotube growth at low substrate temperature via photo-thermal chemical vapour deposition

• Published in: Carbon (New York) 2015-04, Vol.84, p.409-418
• Main Authors: Chen, Jeng-Shiung, Stolojan, Vlad, Silva, S. Ravi P.
• Format: Article
• Language: English
• Subjects: Alpha iron; Carbon; Carbon nanotubes; Catalysts; Chemical vapor deposition; Deposition; Electronics; Nanotubes; Phase diagrams
• ISSN: 0008-6223; 1873-3891
• DOI: 10.1016/j.carbon.2014.12.023

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