Field-electron emission (FE) refers to the emission of electrons from a solid cathode (generally in the shape of a sharp tip) into a vacuum under the influence of a strong electric field of the order of 10⁶–10⁷ V cm⁻¹, otherwise known as cold cathode electron emission. The pointed or conical shape of the cathode strongly enhances the electric field at the tip, originating from biasing the cathode negatively with respect to a nearby anode. FE is a form of quantum mechanical tunneling which occurs when electrons pass through the potential energy barrier at the interface between the cathode and the vacuum. Field emitting cathodes can be integrated into small, lightweight devices and can be operated at high repetition rates due to their rapid on/off switching speed. Potential applications include vacuum microelectronic devices, such as electron guns and microwave power amplifiers, electron microscopy and FE electronic devices, such as flat panel FE displays (FEDs).