What happens when a diode breaks down?
1 Answer. At reverse breakdown voltage on a PN junction diode, you get a large increase in reverse current (normally close to zero) for a small further increase in voltage. Breakdown is non destructive – provided thermal effects do not destroy the diode.
What happens to PN and Zener diode during breakdown?
When we increase the reverse voltage across the pn junction diode, what really happens is that the electric field across the diode junction increases (both internal & external). Zener breakdown phenomena occurs in a pn junction diode with heavy doping & thin junction (means depletion layer width is very small).
Why does a Zener breakdown occur in a PN junction?
The Zener breakdown mainly occurs because of a high electric field. When the high electric-field is applied across the PN junction diode, then the electrons start flowing across the PN-junction. Consequently, expands the little current in the reverse bias.
How does temperature affect the breakdown voltage of a Zener?
The valence electrons are pushed to conduction due to the energy imparted by accelerated electrons, which gain their velocity due to their collision with other atoms. The increase in temperature decreases the breakdown voltage. The increase in temperature increases the breakdown voltage.
Where does the Zener breakdown and avalanche breakdown occur?
The Zener and Avalanche breakdown both occur in diode under reverse bias. The avalanche breakdown occurs because of the ionisation of electrons and hole pairs whereas the Zener diode occurs because of heavy doping. These are explained below in details.
Why does an ordinary diode suffer an avalanche breakdown rather than a Zener?
Avalanche break down occurs due to thermal collision caused by the increased reverse bias voltage, while the Zener breakdown occurs due to the strong electric field caused by the high doping (narrow depletion region). Therefore, an ordinary diode can withstand large reverse bias voltage before the avalanche breakdown happens.