Electron emission tip at extremely low bias voltage

We report the invention of a modification technique of tungsten tip, which results modified tip apex capable of emitting electrons at extremely low bias voltage. Field-ion microscope induces the structural switching of the oxidized apex at room temperature, which is frozen out at low temperature. Thus modified tips exhibit an extraordinary decrease in applied bias needed for electron emission (typically from -300 to -3.8 V). Electron emission shows good angular confinement with an opening angle of less than 2°. Such special tip is repeatedly reproducible and stable for several hours at low temperature.