ELECTRON-EMISSION FROM FERROELECTRIC MATERIALS

Ferroelectric materials are a new class of electron emitters. Electron emission occurs due to the appearance of an unscreened charge and an electrostatic field at the polar surfaces of these crystals under pyroelectric, piezoelectric, and anomalous photovoltaic effects as well as during spontaneous polarization reversal. Small external perturbation (for example, a temperature variation of a few degrees or less) is enough for this emission effect to occur. Emission current density up to 10(3)A cm-2 and electron energy up to about 10(5) eV have been reported. It is shown that this phenomenon drastically differs from other kinds of electron emissions. The physical nature of this effect is discussed.