I have read the zener diode. It acts as a voltage regulator. In the Zener diode V-I characteristics, After the zener breakdown, the voltage remains constant at the breakover voltage while allowing enormous amount of current through it. The voltage simply doesnt increase or decrease after attaining the zener breakdown but current can increase to a very high value or even a very low value. But, how can a device allow enormous amounts of current through it while maintaining the voltage across it at a constant value? What happens inside the zener diode after the breakdown voltage? Please explain the internal structure after zener breakdown. Thanks!