As we all know, the diode(Wikipedia) is of forward conduction. When the reverse voltage is applied at both ends of the diode, which lead to the electrons can’t pass through the diode, so that the diode is equivalent to an open circuit.
At this moment, if the reverse voltage is large enough, which depends on the voltage at both ends of the diode while the diode is connected backwards, the diode will form a reverse breakdown.
