Raman spectroscopy and field-emission properties of CVD-grown carbon-nanotube films

M. Sveningsson, R. E. Morjan, O. A. Nerushev, Y. Sato, J. Bäckström, E. E.B. Campbell, F. Rohmund

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196 Scopus citations

Abstract

Carbon-nanotube films are very efficient cathodes for field-emission devices. This study presents a comprehensive comparison between structural, spectroscopic and field-emission properties of films of aligned and non-aligned multi-wall nanotubes (MWNTs) which are grown by thermal chemical vapour deposition. Three types of films are investigated: vertically aligned MWNTs with clean and coated nanotube side walls as well as non-aligned MWNT films. Raman spectra taken on the aligned MWNT films consist of many lines of first-, second- and third-order signals. Several lines are reported here for the first time for MWNTs. The presence of the surface coating leads to a decrease and broadening of the higher-order signals as well as an increase in the disorder-induced contributions in the first-order regime. The aligned MWNT films have excellent field-emission properties with very high emission current densities and low turn-on and threshold fields. The presence of a surface coating has no impact on the efficiency of the field-emission process. Films of non-aligned MWNTs show considerably reduced electron-emission current densities and larger critical fields.

Original languageEnglish
Pages (from-to)409-418
Number of pages10
JournalApplied Physics A: Materials Science and Processing
Volume73
Issue number4
DOIs
StatePublished - Oct 2001

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