Electron emission characteristics of a liquid-gallium single cone on a W〈1 1 1〉 field emitter tip

For a W〈1 1 1〉 field emitter tip deposited with gallium, the tip temperatures suitable for the formation of a liquid-gallium single cone and the electron emission characteristics were investigated by using field emission microscopy. The liquid-gallium single cone was successfully formed on the W(1 1 1) facet for the tip temperatures ranging from 800 to 1000 K, which are much higher than the melting point 303 K of gallium. The typical lifetime of the cone was several minutes owing to the thermal evaporation of gallium atoms. The noise of the emission current passing through a probe hole was less than 0.4% for a work time of 20 ms. The angular intensity reached about 10 mA/sr at the total emission current of 1.2 mA.