Z-diode

Zener diode characteristic curve and circuit diagram

Z-diodes (Zener diodes) are diodes that are used to stabilise voltages thanks to their special Doping.

The characteristic curves are almost linear in the Zener diodes' operating range. ${V_Z}$ is virtually constant here. An off-state breakdown can be caused by two things. Depending on the Zener Diode's voltage, either the Zener effect or avalanche effect is responsible for the component's operation.

• In the case of the Zener effect, high doping creates a very thin depletion layer. The voltage at the diode releases charge carriers from their bonds and enables a current to flow. This effect is utilised for voltages up to 5 V.
• In the case of the avalanche effect, low doping creates a relatively wide depletion layer. The few free charge carriers are accelerated by the Force acting in the field and absorb energy. Due to the wide depletion layer, numerous charge carriers collide with a lattice atom before leaving this layer and release further charge carriers from it that are also accelerated and release additional charge carriers. This Collision ionisation creates an avalanche effect.