Zener Diodes & Regulation — A/L Physics

Zener Diode A diode designed to operate in the reverse breakdown region at a precise, stable voltage. Unlike a normal diode which is destroyed by reverse breakdown, a Zener diode is doped to have a sharp, controlled breakdown voltage (Vz). When reverse-biased beyond Vz, it conducts heavily while maintaining a nearly constant voltage across its terminals. This makes it ideal for voltage regulation.

Zener Breakdown The mechanism where a high electric field in the depletion region causes covalent bonds to break, generating free electron-hole pairs. This occurs at relatively low voltages (typically < 5–6 V) and has a negative temperature coefficient (Vz decreases with temperature). For higher voltages (> 6 V), avalanche breakdown dominates, which has a positive temperature coefficient.