Difference Between Zener Breakdown and Avalanche Breakdown

The anode and cathode of the breakdown diode are two-terminal electrical components. The diode permits just one current flow path, and the other direction is prevented. Zener events and avalanches are two events that might cause an electrical breakdown.

The primary distinction between Zener breakdown and avalanche breakdown is the appearance of their processes as a result of the strong electric field. Understanding the difference between Zener breakdown and Avalanche breakdown will help us know how these processes work.

Zener breakdown

When a strong electric field is put across a PN junction diode, a Zener breakdown takes place. As a result, electrons move over the PN junction.

Avalanche breakdown

Avalanche breakdown occurs when a high reverse bias voltage raises the electric field, further causing the depletion area to grow.

Difference between a Zener breakdown and an avalanche breakdown

Parameters	Zener breakdown	Avalanche breakdown
Definition	It happens in Zener diodes with Vz values ranging from 5 to 8 or less than 5 volts.	When the Vz is higher than 8 volts, the p-n junction experiences avalanche breakdown.
Electric field	Strong electric fields exist.	It has a weak electric field.
Voltage	The voltage is unaffected by the breakdown.	After a breakdown, the voltage often fluctuates.
Region of depletion	The depletion region is narrow.	The depletion region is large.
Effect of tunneling	The tunneling effect occurs.	There is no tunneling effect.
The electric connection	Nothing breaks the connection.	The connection is broken.
Mechanism	Due to the strong electric field, it happens.	Because of the collision of free electrons, it happens.
The effect on the junction	Once the voltage is dropped, the junction returns to its original position.	The junction needs to be fixed.
Temperature coeficient	Negative	Positive
A graph curve	It curves sharply.	There is no sharp curve on it.
Temperature and voltage relationship	The relationship is inversely proportional.	Proportionate in a direct manner
Concentration of doping	The junction has a high doping concentration.	There needs to be more doping near the intersection.
Structure	Diode with PN junction	Extremely advanced p and n region
Holes and electrons	The generation of electrons happens.	The generation of a pair of electrons and holes occurs.

After studying the differences between Zener's breakdown and Avalanche's breakdown, let's get into more depth about each.

Zener breakdown

Due to their limited depletion area, p-n junction diodes experience Zener breakdown. The diode's limited depletion zone produces a strong electric field when reverse-biased voltage is raised.

When the applied voltage approaches the Zener voltage, the electric field is powerful enough to remove electrons from their valence band. The parent atom's connection with the valence electrons is broken, and the electrons become free. These free electrons are responsible for moving electric current.

An electron also creates a hole in the atom as it transforms into a free-charge carrier. A significant current can flow through the diode when the Zener voltage is reached because many free charge carriers are formed.

The electric field is significantly strengthened but remains constrained during Zener breakdown, making it difficult for many charge carriers to accelerate. The result is a quantum mechanical phenomenon known as quantum tunneling.

Avalanche breakdown

When a PN junction diode has a thick depletion layer and is moderately doped, avalanche breakdown occurs. It often happens when a strong reverse voltage is put across the diode.

The electric field likewise keeps growing as we raise the reverse voltage. The electric field forces the electrons to break free from a covalent bond. These free electrons strike other nearby atoms as they move over the junction. More free electrons are created as a result of this. The net current flowing across the junction rises due to these electrons' drifting.

Ea = Va/d, where Va is the reverse voltage and d is the width of the depletion layer, may be used to calculate the electric field.

We already know that Zener breakdown occurs below the voltage below the avalanche breakdown voltage. A narrow depletion layer width is the cause of this.

Zener diode applications

It can act as a voltage regulator since the consistent reverse voltage makes it an excellent source for controlling the output voltage.
When a voltage difference between the input and output is detected, a Zener-controlled output switch is employed to flip between the two voltages. In transition, the current Zener regulator switches the output circuit from one Zener voltage to another.
A single Zener diode may restrict one side of a sinusoidal wave while holding the other side fixed at zero in a Zener limiter.
Zener's role in power supply: Zener diodes are useful voltage regulators because they can maintain a steady voltage across a wide current range.

Avalanche diode applications

It protects the circuit from excessive current or voltage.
This diode produces RF noise and is used to make white noise. As a result, it serves as a noise source in radio equipment.
If the reverse bias voltage exceeds the reverse breakdown voltage, it permits current flow without harming itself.
This diode's high capacity multiplication allows it to be used in applications requiring a high current.
Many applications employ this diode as a single photon detector.
Because it functions similarly to a negative resistance device, this diode is used to detect microwave frequencies.
This diode produces a soothing noise.

Conclusion

The key difference between the two is that the avalanche breakdown happens at a greater reverse voltage and is irreversible. In contrast, the Zener breakdown happens at a relatively low reverse voltage and is reversible. As a result, although an avalanche breakdown may irreversibly harm the diode, a Zener breakdown does not harm the diode.

Avalanche and Zener breakdown frequently asked questions

Question 1: Describe the Zener diode.

Answer: The Zener diode is a unique type of diode in which the direction of current flow is switchable between forward and reverse. The voltage drop at the diode remains constant throughout a broad voltage range. Electronic gadgets employ Zener diodes because they can withstand greater voltages.

Question 1: The Avalanche diode: what is it?

Answer: The diode is intended to function under reverse biassing conditions and has a moderately doped junction. The special category of diodes includes both Zener and avalanche diodes. The symbolic meaning for both of them is the same.

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