Ring-shaped field emission patterns from carbon nanotube films

Bojan Zajec, Vincenc Nemanič, Marko Žumer, Eugene N. Bryan, Robert Nemanich

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


Highly symmetric ring-shaped field emission patterns were observed from broad-area flat cathodes prepared by growing a film of vertically aligned carbon nanotubes (CNTs) on TiN coated Si substrates. The images were obtained utilizing a luminescent screen of a specially designed triode cell composed of parallel electrodes. The emission rings sporadically appeared during voltage scans in which the emission patterns and cathode currents were recorded. The fine structure and stability of the rings suggests that their formation is due to an emission state of an individual CNT. The observed patterns are consistent with models that predict the formation of emission rings produced by the inhomogeneous electron emission from CNTs. The macroscopic value of the electric field when the rings were observed was between 0.7 and 2.5 V/μm, and the emission current corresponding to individual rings was estimated to be in the range of 2-4 μA. Numerical simulation of electron trajectories for sidewall emission from similar shaped metallic structures is in qualitative and quantitative agreement with the experimentally observed ring-shaped field emission patterns. The results also appear consistent with a recent model [Marchand M, Journet C, Adessi C, Purcell ST. Phys Rev B 2009;80:245425] based on thermal-field emission due to Joule heating.

Original languageEnglish (US)
Pages (from-to)3332-3339
Number of pages8
Issue number10
StatePublished - Aug 2011

ASJC Scopus subject areas

  • Chemistry(all)
  • Materials Science(all)


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