title: Nearly exclusive growth of small diameter semiconducting single-wall carbon nanotubes from organic chemistry synthetic end-cap molecules.
abstract: The inability to synthesize single-wall carbon nanotubes (SWCNTs) possessing uniform electronic properties and chirality represents the major impediment to their widespread applications. Recently, there is growing interest to explore and synthesize well-defined carbon nanostructures, including fullerenes, short nanotubes, and sidewalls of nanotubes, aiming for controlled synthesis of SWCNTs. One noticeable advantage of such processes is that no metal catalysts are used, and the produced nanotubes will be free of metal contamination. Many of these methods, however, suffer shortcomings of either low yield or poor controllability of nanotube uniformity. Here, we report a brand new approach to achieve high-efficiency metal-free growth of nearly pure SWCNT semiconductors, as supported by extensive spectroscopic characterization, electrical transport measurements, and density functional theory calculations. Our strategy combines bottom-up organic chemistry synthesis with vapor phase epitaxy elongation. We identify a strong correlation between the electronic properties of SWCNTs and their diameters in nanotube growth. This study not only provides material platforms for electronic applications of semiconducting SWCNTs but also contributes to fundamental understanding of the growth mechanism and controlled synthesis of SWCNTs.
authors.affiliation: Department of Electrical Engineering and Department of Chemistry, University of Southern California , Los Angeles, California 90089, United States.
authors.forename: Bilu
authors.initials: B
authors.lastname: Liu
authors.forename: Jia
authors.initials: J
authors.lastname: Liu
authors.forename: Hai-Bei
authors.initials: HB
authors.lastname: Li
authors.forename: Radha
authors.initials: R
authors.lastname: Bhola
authors.forename: Edward A
authors.initials: EA
authors.lastname: Jackson
authors.forename: Lawrence T
authors.initials: LT
authors.lastname: Scott
authors.forename: Alister
authors.initials: A
authors.lastname: Page
authors.forename: Stephan
authors.initials: S
authors.lastname: Irle
authors.forename: Keiji
authors.initials: K
authors.lastname: Morokuma
authors.forename: Chongwu
authors.initials: C
authors.lastname: Zhou
keywords: Carbon nanotubes; chirality; controlled growth; end-cap molecules; metal-free; semiconducting