Development of CNT paste for high-current density field emitters

In this study, we have developed a CNT paste for high-current density field emitters by using a ball-milling process. The ball-milling was used in the CNT paste procedure for effective material dispersion. Material dispersion is one of the most important factors in a paste synthetic process. The ball-milling is a very easy and simple method to produce a printable CNT paste. The CNT paste was made of only a few materials, such as thin multi-walled CNTs (4-6 nm dia.), a nano metal powder (<; 100 nm dia.), an organic powder and a solvent. To form field emitters, the ball-milled CNT paste was printed on the Kovar metal sheet as a cathode plate by using a screen-printing method. The printed CNT paste was fired in the air condition and then the surface treatment was carried out to the printed CNTs. Fig. 1 shows SEM images of the CNT emitter on Kovar metal sheet. The fabricated CNT emitters were vertical-aligned well and had clean surface with little residue.