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In electronics, the Zener effect (employed most notably in the appropriately named Zener diode) is a type of electrical breakdown, discovered by Clarence Melvin Zener. It occurs in a reverse biased p-n diode when the electric field enables tunneling of electrons from the valence to the conduction band of a semiconductor , leading to numerous ...
Zener and avalanche diodes, regardless of breakdown voltage, are usually marketed under the umbrella term of "Zener diode". Under 5.6 V, where the Zener effect dominates, the IV curve near breakdown is much more rounded, which calls for more care in choosing its biasing conditions.
These diodes can indefinitely sustain a moderate level of current during breakdown. The voltage at which the breakdown occurs is called the breakdown voltage . There is a hysteresis effect; once avalanche breakdown has occurred, the material will continue to conduct even if the voltage across it drops below the breakdown voltage.
Breakdown voltage is a characteristic of an insulator that defines the maximum voltage difference that can be applied across the material before the insulator conducts. In solid insulating materials, this usually [citation needed] creates a weakened path within the material by creating permanent molecular or physical changes by the sudden current.
The symbol as shown here is acceptable but could be confused with a Schottky Barrier Diode, which is a different kind of diode, and not a Zener diode. The bends on the cathode bar are different. See the Schottky diode page . To be technically correct we should also show the ISO standard symbol which has only one bend, at 90-degrees.
Both of these breakdown processes are non-destructive and are reversible, as long as the amount of current flowing does not reach levels that cause the semiconductor material to overheat and cause thermal damage. This effect is used to advantage in Zener diode regulator circuits. Zener diodes have a low breakdown voltage. A standard value for ...
Various semiconductor diodes. Left: A four-diode bridge rectifier. Next to it is a 1N4148 signal diode. On the far right is a Zener diode. In most diodes, a white or black painted band identifies the cathode into which electrons will flow when the diode is conducting. Electron flow is the reverse of conventional current flow. [2] [3] [4]
In an avalanche, one carrier collides with other atoms and knocks free new carriers. The result is that for each carrier that starts across a barrier, several carriers synchronously arrive. The result is a wide-bandwidth high-power source. Conventional diodes can be used in breakdown. The avalanche breakdown also has multistate noise.