Fabrication of screen-printed field electron emitter using length-controlled and purification-free carbon nanotubes

The authors fabricated a screen-printed field electron emitter using purification-free and length-controlled carbon nanotubes (CNTs). They used vertically aligned CNTs grown on Si substrates by thermal chemical vapor deposition as the source material for fabricating CNT paste. The length of CNTs was controlled by adjusting the growth time. The amounts of amorphous carbon and catalyst in the source material were less than 1 and 0.5wt%, respectively, which obviated the need to purify the CNTs. The emitter fabricated using source CNTs with a length of over 80μm showed good reproducibility of current density (J)–electric field (E) characteristics. With a low threshold field Eth of 1.5V∕μm, J=1mA∕cm2 was produced. The emitter exhibited good emission stability for 100h. It was found that the length distribution of the standing CNTs was determined in a precise manner when long CNTs were used as the source material, which led to a highly reproducible fabrication of field emitters.