This article covers, the difference between Zener breakdown and Avalanche breakdown.
The major difference between Zener breakdown and Avalanche breakdown is Zener breakdown occurs because of strong electric field. Avalanche breakdown occurs because of the collision of electrons.
A diode is used in electronic circuit to allow the flow of current in only one direction. It blocks the flow of current in reverse direction.
Electrical breakdown in materials, such as semiconductor, conductor and insulator happen due to two phenomena.
- Avalanche breakdown
- Zener breakdown
Avalanche breakdown happens when a very high reverse voltage is applied to terminals of diode. when the applied reverse voltage increases, the electric field across the junction also increases. Due to this electric field, a force acts on electrons at junction and free them from co valent bond.
These free electrons move with high speed across the junction and collide with other atoms. The collision creates more free electrons. A rapid increase in current occurs that destroy the diode physically.
In reverse biased condition, the kinetic energy of electrons in diodes increases. They start moving at very high velocity. These fast moving electrons collide with other atoms and generate free electrons. Further, these free electrons result in high reverse saturation current. This condition in diode is known as Zener breakdown.
Difference between Zener breakdown and Avalanche breakdown
The difference between Zener breakdown and Avalanche breakdown is listed below in tabular form –
Zener breakdown takes place in a very thin junction.
Avalanche breakdown take place in a thicker junction.
Zener breakdown doesn’t result in destruction of diode.
Avalanche breakdown destroys the diode.
The breakdown voltage decreases with increase in temperature.
The breakdown voltage increases with increase in temperature.
VI characteristic of Zener breakdown is very sharp at Vz.
VI characteristic of avalanche breakdown is gradual near Va.
In this, the carrier ( free electrons ) increase is the result of electric field strength.
In this, the carrier ( free electrons ) increase is the result of collision.
This breakdown occurs in diodes that are highly doped.
This breakdown occurs in diodes that are lightly doped.
Zener breakdown depends on the amount of doping.
Avalanche breakdown depends on very high reverse voltage.