Details

Autor(en) / Beteiligte

• Hofmann, S.
• Cantoro, M.
• Kleinsorge, B.
• Casiraghi, C.
• Parvez, A.
• Robertson, J.
• Ducati, C.

Titel

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

Ist Teil von

• Journal of applied physics, 2005-08, Vol.98 (3)

Ort / Verlag

United States

Erscheinungsjahr

2005

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• 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 3nm causes a transition from larger diameter (>40nm), bamboolike carbon nanofibers to small diameter (∼5nm) 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°C, all catalysts showed mainly a tip growth regime and a similar activity on untreated silicon, oxidized silicon, and silicon nitride support.