Environmental stability of carbon nanotube field emitters

Investigation of the current-time (I-t) characteristics of field emission (FE) from single-walled carbon nanotubes (SWNT), does not show any significant dependence on ambient partial pressures to 10e-5 mbar of hydrogen or water. It is however shown that oxygen causes substantial reduction of the FE current and this is believed to be related to reactive etching/oxidation of the nanotubes. By heating the tubes up to 1100 Kelvin an increased instability in the FE current as well as on the field emission microscopy (FEM) screen can be observed. These instabilities become less and less pronounced after repeated annealing steps. FEM during short-time heating reveals dim five-fold as well as six-fold feinstructures. These feinstructure FEM patterns are not stable and have a short lifetime. Resonant tunnelling states as well as FE from nanotube cap states might explain these observations.