- Zener Breakdown Definition: Zener Breakdown is the process where a high electric field in a heavily doped diode causes a sudden increase in current by breaking covalent bonds and releasing valence electrons.
- High Electric Field: A narrow depletion region in a reverse-biased diode creates a high electric field, essential for Zener Breakdown.
- Controllability: The number of charge carriers in Zener Breakdown can be controlled by adjusting the electric field.
- Safe Voltage Levels: Zener Breakdown usually happens below 5V, and with proper heat management, it doesn’t damage the diode.
- Temperature Impact: The Zener Breakdown Voltage decreases with an increase in junction temperature, indicating a negative temperature coefficient.
Zener breakdown is a sudden reverse current in a heavily doped diode once the thin depletion layer produces a high electric field. The layer is narrow because doping is high. A 3 V reverse voltage across about 100 Ao (10 nm) already gives a field of about 3e8 V/m.
That field lets valence electrons tunnel out of bonds and into the conduction band, so reverse current jumps. The event is Zener Breakdown. The knee voltage is the Zener Breakdown Voltage (VZ). Clarence Zener explained the tunneling process in 1934.
The carrier count follows the field, so the current can be held with a series resistor. Zener Breakdown is typical below about 5 V. With heat removed it does not destroy the junction. The knee falls as temperature rises (negative temperature coefficient). Doping sets the voltage in manufacture. A Zener diode is built to use that knee.
