Self-joule heating assisted field emission following the Child–Langmuir law

In this study, stable and long-term field emission properties that completely follow the Child–Langmuir law were successfully observed. A tungsten tip covered with a liquid gallium metal was used. The current characteristics showed three phases. The electron emission first began below half of the threshold voltage for the emission from a bare W chip, and the current increased by 20 μA. Then, the field emission pattern showed multiple disordered blinking spots, which originated Ga Taylor cones and the emission current value reached several mAs. Then, emission current began to follow the Child–Langmuir law, and a clear field emission pattern from {011}-oriented tungsten was observed. Electrons emitted from the submicrometer sized area that is heated by itself with joule heating of current densities greater than 107 A/cm2.