Why is the electric field of a junction in zener diode very high when the depletion region is very thin ??? Pls give a theoretical explanation.
It is NOT the case that the electric field of a junction in zener diode is very high when the depletion region is very thin. The zener breakdown occurs in the heavily doped p-n junction diodes. Heavily doped p-n junction diodes have narrow depletion region.
If reverse voltage is applied on the narrow depletion p-n junction diode, the immobile ions in the depletion region gains energy from the external voltage. Hence, the electric field of the immobile ions increases. As a result, the overall electric field of the narrow depletion region increases.
If the voltage applied on the p-n junction diode is increased to a higher value, a very strong electric field is built in this narrow depletion region. This strong electric field of narrow depletion region applies force on the valence electrons and pulls them from the valence band.
Thus, free electrons and holes are generated as pair. Likewise, a large number of minority carriers are generated in the depletion region. At this point, a small increase in reverse voltage causes sudden rise in reverse current. This sudden rise of reverse current destroys the depletion region or p-n junction.
The strong electric field of the narrow depletion region, which causes the junction breakdown or depletion breakdown, is called avalanche breakdown.
The zener breakdown occurs in the heavily doped p-n junction diodes. Heavily doped p-n junction diodes have narrow depletion region.
If reverse voltage is applied on the narrow depletion p-n junction diode, the immobile ions in the depletion region gains energy from the external voltage. Hence, the electric field of the immobile ions increases. As a result, the overall electric field of the narrow depletion region increases.
If the voltage applied on the p-n junction diode is increased to a higher value, a very strong electric field is built in this narrow depletion region. This strong electric field of narrow depletion region applies force on the valence electrons and pulls them from the valence band.
Thus, free electrons and holes are generated as pair. Likewise, a large number of minority carriers are generated in the depletion region. At this point, a small increase in reverse voltage causes sudden rise in reverse current. This sudden rise of reverse current destroys the depletion region or p-n junction.
The strong electric field of the narrow depletion region, which causes the junction breakdown or depletion breakdown, is called avalanche breakdown.
