What does the term “reverse breakdown” in diodes refer to?

The term "reverse breakdown" in diodes specifically refers to the phenomenon that occurs when a diode is subjected to a reverse voltage that exceeds its specified breakdown voltage, leading to a significant increase in current flow in the reverse direction. This condition allows the diode to conduct reverse current, often resulting in potential thermal damage if not managed properly.

In normal operations, diodes are designed to block current flow in the reverse direction until the reverse voltage approaches this breakdown threshold. Once this threshold is surpassed, the reverse current can dramatically increase, which is a critical aspect for applications such as Zener diodes where controlled breakdown is utilized for voltage regulation. Under reverse breakdown conditions, the diode effectively changes from its blocking state to a conductive state in the opposite direction, which is why the definition focuses on the excessive reverse voltage causing current to flow.

This behavior contrasts with the other options, where normal operation, stopping conduction, or increasing input voltage do not accurately describe the phenomenon of reverse breakdown.