Field emission from short and stubby vertically aligned carbon nanotubes

Electron emission from vertically aligned carbon nanotubes grown by plasma enhanced chemical vapor deposition has been measured using a parallel plate anode and a 1 mum tungsten probe. The field emission characteristics were measured as a function of the nanotube diameter, length, and areal density. It was found that less densely populated short and stubby nanotubes with diameters of 200 nm and heights of 0.7 mum showed the best emission characteristics with a threshold voltage of 2 V/mum and saturation emission current density of 10 mA/cm2. A triple junction between nanotube, substrate, and vacuum is proposed to explain our results. (C) 2001 American Institute of Physics.