Tantalum-oxide catalysed chemical vapour deposition of single- and multi-walled carbon nanotubes

Abstract

Tantalum-oxide thin films are shown to catalyse single- and multi-walled carbon nanotube growth by chemical vapour deposition. A low film thickness, the nature of the support material (best results with SiO₂) and an atmospheric process gas pressure are of key importance for successful nanotube nucleation. Strong material interactions, such as silicide formation, inhibit nanotube growth. In situ X-ray photoelectron spectroscopy indicates that no catalyst reduction to Ta-metal or Ta-carbide occurs during our nanotube growth conditions and that the catalytically active phase is the Ta-oxide phase. Such a reduction-free oxide catalyst can be technologically advantageous.