How does avalanche breakdown occur in pn junction diode?

How does avalanche breakdown occur in pn junction diode?

Avalanche breakdown occurs in a p-n junction diode when it is moderately doped and has a thick junction (i.e. its depletion layer width is high). Avalanche breakdown occurs because of the ionization of electron and hole pairs whereas the Zener breakdown occurs because of heavy doping.

What do you mean by breakdown explain the avalanche breakdown in detail?

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 causes breakdown voltage in pn junction?

This current is due to the movement of minority charge carriers and it is almost independent of the voltage applied. If reverse bias is made too high, the current through PN junction increases abruptly and the voltage at which this phenomenon occurs is called breakdown voltage .

What is avalanche breakdown in a junction?

What is Avalanche Breakdown? The avalanche breakdown occurs when a high reverse voltage is applied across the diode. As we increase the applied reverse voltage, the electric field across the junction increases. This electric field exerts a force on the electrons at the junction and frees them from covalent bonds.

Why does breakdown voltage occur?

Breakdown occurs when the electric field becomes strong enough to pull electrons from the molecules of the material, ionizing them. The released electrons are accelerated by the field and strike other atoms, creating more free electrons and ions in a chain reaction, flooding the material with charged particles.

What is breakdown voltage in a PN junction?

The maximum reverse bias voltage that can be applied to a p-n diode is limited by breakdown. Breakdown is characterized by the rapid increase of the current under reverse bias. The corresponding applied voltage is referred to as the breakdown voltage. The breakdown voltage is a key parameter of power devices.

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

The collisions happening in avalanche breakdown dissippiate thermal energy and may cause damage of normal diodes. Whereas zener doesn’t have much thermal dissippiation. Thus after reaching zener breakdown voltage zener remains undamaged, can be used again.

Why does avalanche breakdown occur in a PN junction?

Avalanche breakdown occurs due to a phenomenon called impact ionization. And impact ionization is a process in which electrons gain very high kinetic energy. And it has such a high energy that it can run into on electrons in the valence band or the bonding electrons and break the bond.

Which is a minority carrier in avalanche breakdown?

An avalanche of current carriers is produced in a very short time due to this breakdown of pn junction diode. Holes in n side and electrons in p side are minority carriers. Current carriers in pn junction diode are holes and electrons.

How is an avalanche of current carriers produced?

Avalanche Breakdown is the process of current carrier multiplication due to collision of thermally generated minority carriers with crystal ions in a lightly doped reverse biased pn junction diode. An avalanche of current carriers is produced in a very short time due to this breakdown of pn junction diode.

What is the relationship between avalanche breakdown and Zener breakdown?

In Zener breakdown, the breakdown voltage depends on the temperature of P-N junction.The breakdown voltage decreases with increase in the junction temperature. The avalanche breakdown is observed in the Zener Diodes having V z having than 8 V. In the reverse biased condition, the conduction will take place only due to the minority carriers.