  The electron field emission of patterned films of nitrogenated carbon
nanotubes is shown to be decisively influenced by the deposition conditions.
The growth was carried out by decomposing methane in a nitrogen/ammonia
atmosphere using hot filament chemical vapor deposition (CVD). The diameter of
the produced tubes depended critically on the distance between substrate and
filament, and the field emission properties applied fields needed for electron
emission, field amplification factor) could be directly correlated to the film
morphology. This demonstrates the possibility of tuning the field emission
properties of such film emitters. For arrays of nanotubes thinner than 50 nm,
the onset of field emission was observed at about 4 V/um, and a current density
of 10 mA/cm2 was obtained for an applied field of 7.2 V/um.
