Difference Between Avalanche Breakdown and Zener Breakdown

The main difference between Zener breakdown and avalanche breakdown is their mechanism of occurrence. Zener breakdown occurs because of the high electric field whereas, the avalanche breakdown occurs because of the collision of free electrons with atoms. Both these breakdowns can occur simultaneously.

1. What is meant by avalanche breakdown?
2. What is meant by Zener avalanche breakdown?
3. What causes avalanche breakdown?
4. What is Zener effect and Avalanche effect?
5. What is the importance of Zener breakdown over avalanche breakdown?
6. What is the zener breakdown voltage?
7. What is the main cause of Zener breakdown?
8. What is reverse breakdown?
9. Why zener diode is heavily doped?
10. Why avalanche breakdown is considered to be a destructive one while zener breakdown is not?
11. Is avalanche breakdown reversible?
12. Why does avalanche breakdown increase with temperature?

What is meant by avalanche breakdown?

Avalanche breakdown (or “the avalanche effect”) is a phenomenon that can occur in both insulating and semiconducting materials. It is a form of electric current multiplication that can allow very large currents within materials which are otherwise good insulators. It is a type of electron avalanche.

What is meant by Zener avalanche breakdown?

Valence electrons which break free under the influence of the applied electric field can be accelerated enough that they can knock loose other electrons and the subsequent collisions quickly become an avalanche. This process of sudden release of electrons is known as zener breakdown.

What causes avalanche breakdown?

Avalanche breakdown is caused by impact ionization of electron-hole pairs. A very little current flows under reverse bias conditions and depletion region increases. The electric field in the depletion region of a diode can be very high. Electron/holes that enter the depletion region undergo a tremendous acceleration.

What is Zener effect and Avalanche effect?

The Zener and the avalanche effect may occur simultaneously or independently of one another. In general, diode junction breakdowns occurring below 5 volts are caused by the Zener effect, whereas breakdowns occurring above 5 volts are caused by the avalanche effect.

What is the importance of Zener breakdown over avalanche breakdown?

The main difference between Zener breakdown and avalanche breakdown is their mechanism of occurrence. Zener breakdown occurs because of the high electric field whereas, the avalanche breakdown occurs because of the collision of free electrons with atoms. Both these breakdowns can occur simultaneously.

What is the zener breakdown voltage?

The Zener Breakdown is observed in the Zener diodes having Vz less than 5V or between 5 to 8 volts. When a reverse voltage is applied to a Zener diode, it causes a very intense electric field to appear across a narrow depletion region.

What is the main cause of Zener breakdown?

The main cause of zener breakdown is high doping concentrations. The breakdown is a condition when upon increasing the voltage in small amounts; we experience a massive current flow in the device. Zener breakdown occurs when we apply reverse bias to a heavily doped diode.

What is reverse breakdown?

When reverse bias is increased, the electric field at the junction also increases. ... High electric field causes covalent bonds to break resulting in generation of large number of charge carriers. This causes a large current to flow. This mechanism of breakdown is called zener breakdown .

Why zener diode is heavily doped?

The Zener diode, however, is heavily doped, as a result, they have a thin depletion region. Zener diode, under forward bias condition, conducts like a normal diode and if the applied voltage is higher than the reverse voltage then it conducts in the reverse bias condition too.

Why avalanche breakdown is considered to be a destructive one while zener breakdown is not?

It does not involve collision of carriers with the lattice atoms(drift current). The collisions happening in avalanche breakdown dissippiate thermal energy and may cause damage of normal diodes. Whereas zener doesn't have much thermal dissippiation.

Is avalanche breakdown reversible?

Is Avalanche Breakdown Reversible? Avalanche breakdown is not reversible while Zener breakdown is reversible. Avalanche Breakdown occurs due to the collision of accelerated charge carriers with the adjacent atoms and due to carrier multiplication.

Why does avalanche breakdown increase with temperature?

In avalanche breakdown , a bunch of electrons knocks out other electron to conduction band creating electron hole pair. Due to increase in temperature ,vibrations of atoms increases and thus reduces the mean free path for electrons. Hence in avalanche breakdown, breakdown voltage increases with increase in temperature.