On the turn-on field of carbon nanotube cathode

摘要

Carbon nanotube (CNT) cathode is considered a hopeful new cathode for various vacuum electronics devices, and the most important specifications are turn-on field and current density. One factor that affects turn-on field most is the Schottky barrier between CNT and the metal electrode in CNT cathode. We manage to reduce this barrier by using metal-CNT hot-bonding process and found the turn-on field improved to 1–2 V/μm. Current density is found related to microscopic shielding effect, and the heating results to shifting of emission sites, thus a lowered average current density and fluctuation in emission current.