Growth Mechanism of Well Aligned Semiconducting Single-walled Carbon Nanotubes on Quartz Substrate

W. Zhou, S. Zhan, L. Ding, J. Liu
Duke University, US

Keywords: CNT, carbon nanotubes


Even though the devices made from individual nanotubes have shown outstanding performances such as high mobility, high current, high thermal conductivity, good chemical and mechanical stability, the high hope for the next generation of carbon nanotube based electronics is hampered by several major problems. Among them are the lack of reliable methods to control the alignment and position of nanotubes as well as and perhaps most problematically, the simultaneous growth of nanotubes with different chiralities, yielding random mixtures of metallic and semiconducting nanotubes. Even though the post-growth separation of metallic from semiconducting SWNTs have made good progress, the alignment and assembly of the separated nanotubes into devices are still challenging and not suitable for large scale fabrication. Consequently, a method that can directly produce well aligned arrays of pure semiconducting nanotubes is thought to be the ideal choice for large scale fabrication of nanotubes FETs. In this talk, we show that such a method is not a dream. Recently we have successfully synthesized high-density, horizontally aligned SWNTs on quartz wafers, and the thin-film transistors (TFTs) based on this SWNT array show high on-driving current density (up to ~220 μA/μm). Additionally, through systematic studies, we proposed and confirmed the high growth selectivity originates from the etching effect and chemical reactivity difference of metallic and semiconducting nanotubes...