The field emission properties of films of aligned multiwalled nanotubes produced by plasma-enhanced chemical vapor deposition are studied as a function of their length. The measured turn-on and threshold electric fields decrease strongly with increasing nanotube length, reaching values of below 1 V/μm for the longest nanotubes investigated (170 μm). The field enhancement factors are discussed and the remarkable performance of the longest nanotube films is attributed to secondary thornlike growth at the tips.
Bibliographical noteFunding Information:
This work was financially supported by the Swedish Foundation for Strategic Research (SSF) and the EU through Contract No. HPRN-CT-2000-00026.