What happens when you expose a diode beyond the break-down voltage, does it become conductive in both senses or non-conductive in both senses?


1 Answer 1


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. Zener diodes are devices with specified low breakdown voltages that exploit this effect.

So for example a 10V 1W Zener could take 0.1A in reverse breakdown current continuously. If you exceed this thermal rating then the diode will be damaged in an unpredictable way.

  • \$\begingroup\$ Can you specify also the case when thermal effects do destroy the diode, what possibilities can this outcome have, is there a possibility that it becomes conductive in both senses ? \$\endgroup\$ Oct 12, 2015 at 14:22
  • \$\begingroup\$ I can't specify it. It could become conductive in both directions, or become conductive in neither. Its not predictable - basically you have melted it! \$\endgroup\$
    – Icy
    Oct 12, 2015 at 14:27

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