CNT electron source with uniform emission distribution

The carbon nanotube (CNT) has been well known as a good field emission material by its superior structure, such as small radius and high aspect ratio. It has also been said that a large sized cathode plate can be easily fabricated at low cost by a CNT paste printing technique. However, the CNT has a cohesive characteristic in its nature and the printed layer becomes a rugged surface if an ordinal dispersant is used. The surface roughness impedes field uniformity on the CNT layer and leads to degradation of the emission uniformity. In the following, we describe the techniques used to fabricate a smooth CNT layer and to activate the layer for good emission uniformity. To suppress the cohesion of CNT in the paste, we applied newly developed dispersive materials. After printing the paste, a surface roughness (Ra) of less than 0.2 μm was achieved.