Reverse breakdown state.

The zener diode is one of the diodes, and also has the basic unidirectional conduction characteristics of the diode, that is, the forward voltage is on, and the reverse voltage is not. Zener diode is used to stabilize the voltage by its characteristic that the current will rise sharply when reverse breakdown occurs. It shows that the dynamic resistance Rz at this time, that is, the ratio of the increased voltage divided by the increased current, is relatively small, which will make the fluctuation of external voltage have less impact on the voltage at both ends of the zener diode.