Novel geometry of carbon nanotube field emitter to achieve high current densities

The authors report on further improvement of carbon nanotube pillar array (CPA) cathodes for achieving higher current densities. A novel geometry of patterned carbon nanotube (CNT) emitter pillar array with increased edge area, was presented. This new geometry differs from the CNT pillar in that it has an open-center, similar to the structure of a toroid. The toroid CNT pillar with an inner radius of 5 ¿m and an outer radius of 15 ¿m increases the total emitting edge area, while minimizing electric field screening by eliminating the CNTs in the middle of each pillar. This leads to a greater total current from the cathode due to an increased number of sites that emit.