Electron Emission Properties of Liquid-Gallium on a Tungsten Field Emitter Tip

Abstract
For <110> and <111> oriented tungsten tips deposited with liquid-gallium, electron emission patterns and emission current characteristics were investigated by field emission microscopy. When the tip voltage was applied for the first time after deposition of gallium, stable liquid-gallium cones were formed on the remolded facets for thicknesses of 1.5 ~ 5nm and DC electron emission occurred. The total emission current obeyed the Child-Langmuir's law. This means that the stabilization mechanism of liquid-gallium cones is the space-charge effect. These experimental results are very similar to those for the liquid-lithium deposited tungsten tips already reported. When the applied voltage was decreased to zero and again increased, weak distorted pattern appeared on the same facets and became bright gradually. The emission current monotonously increased with the applied voltage. In this case, no liquid-gallium cone seems to be formed and the electron emission probably occurs from the liquid droplet, as mentioned by Rao et al.