Question

Distinguish between Avalanche breakdown and Zener breakdown.

Answer 1

Hint: In this question use the concept that although both the zener as well as avalanche breakdown occurs in the reverse biased region of a diode but avalanche breakdown occurs at more negative reverse biasing potential that is more towards left side of negative x-axis as compared to the zener breakdown. This will help approach the solution.

Complete step-by-step answer:

The difference between the Avalanche breakdown and Zener breakdown are as follows:

S.No	Avalanche breakdown	Zener breakdown
1	It will occur in the diodes that are lightly doped.	It will occur in the diodes that are highly doped.
2	The VI characteristics of an Avalanche breakdown has not a very sharp curve.	The VI characteristics of a Zener breakdown has a very sharp curve.
3	The increase in temperature increases the breakdown voltage.	The increase in temperature decreases the breakdown voltage.
4	The process of applying the high voltage and increasing the free electrons or electric current in the semiconductor and insulating materials are called avalanche breakdown.	The process in which the electrons move through the barrier from the valence band of the p type material into the conduction band of the n type material is known as Zener breakdown.
5	Avalanche breakdown occurs because of the collision of free electrons with the atoms.	Zener breakdown occurs only because of the high electric field in reverse bias condition.
6	This is observed in Zener diodes having Zener breakdown voltage ${V_z}$ greater than -8 volts.	This is observed in Zener diodes having Zener breakdown voltage ${V_z}$ between -5 to -8 volts.

So this is the required difference between the avalanche breakdown and Zener breakdown.

Note – Avalanche breakdown is a non-destructive and a reversible process, that means if we decrease the voltage down the current eventually decreases and crossing a certain point may cause a breakdown but however if we increase the potential again then increase in the current can be seen.