Electron emission current degradation is often observed from printed single wall carbon nanotube emitters during field emission process. After a highly imposed emission, structural deformation of emitters from thin crystalline nanotube bundle to thick amorphous-type carbon fiber was observed. This deformation seems to relate to the current degradation, deteriorating the efficiency of field emission either by increasing the resistance of emitters or by decreasing the field enhancement factor of emitter tips. Two possible mechanisms of structural deformation are internal structural transformation by Joule heating under excessively imposed emission current and continuous adsorption of carbon particles on actively working emitters.

A screen-printed carbon nanotube ͑CNT͒ paste for applications to field emission emitters was treated with He, He/ Ar, and He/ N 2 atmospheric pressure plasmas. The effect of the different plasma treatments on the field emission characteristics of the screen-printed CNTs was investigated. The atmospheric pressure plasma applied to the screen-printed CNT paste for 10 s resulted in a reduction in the turn-on electric field. In particular, the application of a He/ N 2 plasma treatment decreased the turn-on electric field from 3.13 to 1.29 V / m and increased the field enhancement factor from 737 to 2775 after the treatment. These results suggest that an adequate atmospheric pressure plasma treatment of screen-printed CNTs can be effective in enhancing the field emission properties.