Boosting field electron emission of carbon nanotubes through small-hole-patterning design of the substrate

High field emission of carbon nanotube (CNT) cold cathodes is realized by printing modified CNT paste on small-hole-patterned substrates. The field emission characteristics and stability of samples under DC continuous and pulse driving modes have been investigated. The results show that the maximum emission current of CNT emitters can be up to 45 mA at an electric field of 2100 V (7.0 V mu m-1), corresponding to a high current density of 643 mA cm-2 under continuous mode. The cathodes also demonstrate stable electron emission without obvious attenuation. In pulse (10 mu s and 200 Hz) mode, the peak current can reach 250 mA and the corresponding current density is 3.57 A cm-2 under an electric field of 14.0 V mu m-1. The hole-patterned CNT cathode presents unique advantages in field emission current, stability and especially endurance of high electric field. This work makes it possible to fabricate highly efficient emission CNT cold electron sources, which have broad application prospects in vacuum electronic devices requiring both large current and high current density.