Diode Characteristics- Zener Vs Normal Diode

[reachme09]

Can anyone tell me why normal Diode cannot be used as a Zener Diode.
If you look at the reverse characteristics graph.. Both has the same graph with voltage difference.
If i can make the reverse breakdown voltage of normal Diode equal to zener Diode, Then Why can't it can be used as Zener Diode.

Please Dont say the Doping is Different.. Please respond if you have any Valid answer

Thanks

 

[steinar96]

It's all about the doping, there is no escaping that

Doping is required to affect both the reverse-breakdown voltage and the mechanism by which it happens. For conventional diodes once they break down they go through a avalanche breakdown such that even though the voltage goes bellow the reverse voltage again it continues to conduct due to hysterisis effect, normal diodes rarely survive this.

Zener diodes break down with a slightly different but similar mechanism and stop conducting again when the voltage has decreased bellow the reverse breakdown (no hysterisis effect). Instead of avalanching at the rated voltage breakdown electrons instead "tunnel" trough from the valence band into the conduction band. This is achieved trough heavy doping which decreases the barrier and increases the electric field between those bands.

Normal diodes are not made to survive avalanche (and also suffer from a hysterisis effect). Think of it like a avalanche. Once it's begun it doesnt stop very easily. Which is why they can not be used for that application.