A semiconductor used on British motorcycles for many years as a voltage regulator. When the voltage across the Zener diode reached a certain point, the element would begin to conduct current, routing it to ground, thus preventing the battery from overcharging.
A diode that, above a certain reverse voltage (the zener value), has a sudden rise in current. The voltage across the diode remains essentially constant for any further increase in reverse current, up to the allowable dissipation rating.
A semiconductor diode with high doping levels on each side of the junction. If the junction is reverse-biased, breakdown occurs at a well-defined potential, giving a sharp increase in current. The effect is called Zener breakdown; it occurs because electrons are excited directly from the valence band into the conduction band. Zener diodes are used as voltage regulators. See also diode. [DC99
A Zener diode is a type of diode that permits current to flow in the forward direction like a normal diode, but also in the reverse direction if the voltage is larger (not equal to, but larger) than the rated breakdown voltage known as "Zener knee voltage" or "Zener voltage".