Difference Between Zener Breakdown and Avalanche Breakdown

The difference between Zener breakdown and Avalanche breakdown is a very important topic to study in semiconductors. When a diode is reverse-biased with an increase in voltage the reverse current also increases. This phenomenon is called breakdown. When the PN diode is reverse biased, a breakdown occurs called PN junction breakdown. Both Zener and avalanche breakdowns are the phenomena for PN junction breakdown. Zener breakdown is the breakdown in which free electrons generate reverse saturation current resulting in breakdown. Avalanche breakdown is breakdown due to increased resultant current produced by a high electric field obtained by applying a high reverse voltage across the diode.

In this article, you will learn about Zener breakdown, Avalanche Breakdown, and the difference between these two.

What is Zener Breakdown?

• Zener breakdown is the phenomenon that takes place due to the large reverse saturation current obtained from free electrons present in the junction.
• The reverse-biased diode grows the kinetic energy of the electrons resulting in an increase in the velocity of the electrons.
• These increased velocity electrons combine with other atoms and release free electrons which in turn is responsible for the reverse saturation current.
• It occurs in heavily doped junctions.
• Its depletion layer is thin.
• The electric field produced is strong.

What is Avalanche Breakdown?

• Avalanche breakdown is the phenomenon in which a high electric field is produced by applying high voltage across the diode which in turn increases the resultant current.
• It occurs in lightly doped junctions.
• Its depletion layer is thick.
• The electric field produced is weak.

What is the Difference between Zener Breakdown and Avalanche Breakdown?

The Zener breakdown and Avalanche breakdown have some similarities and differences. The Zener breakdown is observed because of the reverse saturation current from free electrons generated by the reverse biased junction whereas the Avalanche breakdown is observed because of the current generated by the high electric field produced by applying high reverse voltage across diode. The junction doping is high in Zener breakdown whereas it is light in Avalanche breakdown. The electric field produced by the Zener breakdown is strong but the electric field produced in Avalanche breakdown is weak. Finally, the VI curve is sharp in case of Zener breakdown and the VI curve is less sharp in case of Avalanche breakdown.

Tabular Difference Between Zener Breakdown and Avalanche Breakdown

Here are the points of difference between Zener breakdown and Avalanche Breakdown:

Characterization	Zener Breakdown	Avalanche breakdown
Definition	Zener breakdown is breakdown which occurs due to reverse saturation current obtained from free electrons produced by reverse biased junction.	Avalanche breakdown is breakdown which occurs due to current produced by high electric field caused by applying high reverse voltage across the diode.
Junction Doping	Junction doping is high.	Junction doping is light.
Depletion layer	Its depletion layer is thin.	Its depletion layer is thick.
Electric field	Electric field produced is strong.	Electric field produced is weak.
Zener voltage	It ranges from 5 to 8V.	It is greater than 8V.
VI Curve	It has sharp VI curve.	It has less sharp VI curve.
Temperature	Decreased breakdown voltage increases temperature.	Increased breakdown voltage increases temperature.

Similarities Between Zener Breakdown and Avalanche Breakdown

• Both Zener breakdown and Avalanche breakdown are types of PN junction breakdown.
• Zener breakdown and Avalanche breakdown both produces electric fields.
• In both Zener breakdown and Avalanche breakdown voltages affects temperature

Conclusion – Zener Breakdown vs Avalanche Breakdown

From the above description we conclude that Zener breakdown occurs due to reverse saturation current produced due to free electrons generated by reverse biased junction whereas Avalanche breakdown occurs due to current produced by high electric field caused b applying high reverse voltage across the diode. In Zener breakdown Zener voltage ranges from 5V to 8V whereas in Avalanche breakdown it is greater than 8V. Electric field produced in the Zener breakdown is weak but strong in the Avalanche breakdown. The VI curve of the Zener breakdown is sharper than Avalanche breakdown.

FAQs on Difference Between Zener Breakdown and Avalanche Breakdown

1. What is Avalanche breakdown?

When high electric field is produced by applying high reverse voltage across the diode, it generates free electrons hence, current at the junction. Due to this current breakdown occurs called the avalanche breakdown.

2. What is Zener breakdown?

 The phenomena in which reversed biased diode produces free electrons generated by collision of high velocity electrons and other atoms. The free electrons produce increased reverse saturation current resulting is breakdown called Zener breakdown.

3.  What is PN junction breakdown?

When the PN diode is reversed biased, the increase in voltage increases the reverse saturation current. This phenomenon is called as the PN junction breakdown.

4. State about the depletion layer in Zener breakdown.

The depletion layer in Zener breakdown is thin.

5. What type of electric field is produced in the Avalanche breakdown?

The electric field produced in the Avalanche breakdown is weak in nature.