What happens to diode when avalance breakdown?

Question

Is the diode damaged if reverse voltage is greater than the avalance breakdown voltage of the diode

Answer 1

Internally, when the reverse voltage is so high, free roaming electrons in the semiconductor will smash into atoms causing electrons from those atoms to knock loose and smash into other atoms. This phenomenon can quickly expand at an exponential rate and cause very large amounts of current to flow in otherwise well-insulated materials.

Yes, the diode will be damaged if not corrected quickly, but applications exist (especially in power transmission) that use this phenomenon to kill power if unexpected surges occur.

Answer 2

It heats up per Power = E*I or I^2*R. When it gets to about 175C junction temperature, the silicon starts to become damaged. If the heat continues for any length of time, the diode is smoked.

If you put a resistor outside that limits the current so the diode doesn't overheat, it will not be affected in any way. Isn't that cool?