Fabrication and characterization of a 3D-structured field emitter using carbon nanotube.

Carbon nanotube has good electrical properties and a high aspect ratio, which enable it to obtain a high current at a low voltage due to its high field. Due to the life and uniformity of their emission tips, carbon nanotube field emitters are hard to commercialize. A field emitter with a three-dimensional (3D) structure was fabricated in this study to overcome such problems. In the 3D-structured field emitter, the field emission tips are located only at the vertical plane, where an enlarged field emission area can be attained. To fabricate the tip of the 3D-structured field emitter, carbon nanotube/silver nanocomposite powders were fabricated via molecular-level mixing and were sprayed at a substrate with good attachment and homogeneous dispersion between the CNT tips and the silver. The field emission properties of the 3D-structured field emitter were then determined and compared with those of a flat field emitter. The field emission area of the 3D-structured field emitter was found to be 4.5 times larger than that of the flat field emitter, with six times higher current density. Moreover, the 3D-structured field emitter had better stability than the flat field emitter. At a high gate field, the emission images of the 3D-structured field emitter showed light spots expanded towards the gate direction.