Effects of catalyst film thickness on plasma-enhanced carbon nanotube growth

Journal Article · Mon Aug 01 04:00:00 EDT 2005 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.1989432· OSTI ID:20714029

Hofmann, S; Cantoro, M; Kleinsorge, B; Casiraghi, C; Parvez, A; Robertson, J; Ducati, C ^[1]

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1. Department of Engineering, University of Cambridge, Cambridge CB2 1PZ (United Kingdom)

A systematic study is presented of the influence of catalyst film thickness on carbon nanostructures grown by plasma-enhanced chemical-vapor deposition from acetylene and ammonia mixtures. We show that reducing the Fe/Co catalyst film thickness below 3 nm causes a transition from larger diameter (>40 nm), bamboolike carbon nanofibers to small diameter ({approx}5 nm) multiwalled nanotubes with two to five walls. This is accompanied by a more than 50 times faster growth rate and a faster catalyst poisoning. Thin Ni catalyst films only trigger such a growth transition when pretreated with an ammonia plasma. We observe a limited correlation between this growth transition and the coarsening of the catalyst film before deposition. For a growth temperature of {<=}550 deg. C, all catalysts showed mainly a tip growth regime and a similar activity on untreated silicon, oxidized silicon, and silicon nitride support.

• OSTI ID: 20714029
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 3 Vol. 98; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ACETYLENE
AMMONIA
CARBON
CATALYSTS
CHEMICAL VAPOR DEPOSITION
COBALT
CRYSTAL GROWTH
IRON
MIXTURES
NANOTUBES
NICKEL
PLASMA
POISONING
SILICON
SILICON NITRIDES
THICKNESS
THIN FILMS