Characteristic curve of a Zener diode

Principle

Zener diodes are silicone diodes with a high level of p and n area doping. They behave like normal Si-diodes in the forward direction. Voltage connected in the reverse direction produces a strong electric field in the barrier layer. When the voltage dependent on the preselected doping level, the breakdown voltage, is exceeded, the electric field causes pairs of charge carriers to be released, resulting in a sharp increase in current. This causes the diode resistance to decrease. If the external voltage is increased even further, then the diode current increases sharply. This results in an increase in voltage at the multiplier while the increase in voltage at the diode is minimal. It is important to have the right sized multiplier to ensure that the product of the breakdown voltage and diode current (dissipation power) does not exceed the nominal value for the diode type. Exceeding the nominal value alters the barrier layer, rendering it useless and effectively destroying it.
The fact that the diode voltage varies only minimally in the breakdown range when the external voltage is varied can be used to create a constant reference voltage and to stabilise voltage. The diode type must be selected according to the desired voltage.

Benefits

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Tasks

How do Zener diodes differ from normal rectifier diodes?

Investigate the relationship between current and voltage for a Zener diode in forward and reverse direction.