  An oxygen assisted hydrocarbon chemical vapor deposition (CVD) method is
developed to afford large-scale highly reproducible ultra high-yield growth of
vertical single-walled carbon nanotubes (SWNT). It is revealed that reactive
hydrogen (H)-species, inevitable in hydrocarbon-based growth, are damaging to
the formation of sp2-like SWNTs. The addition of oxygen scavenges H-species and
provides a powerful control over the C/H ratio to favor SWNT growth. The
revelation of the roles played by hydrogen and oxygen leads to a unified and
universal optimum growth condition for SWNTs. Further, a versatile method is
developed to form vertical SWNT films on any substrate, lifting a major
substrate-type limitation for aligned SWNTs.
