Zener Diode Working in Reverse Biased
In forward-biased conditions, the Zener Diode works like any normal diode but in the reverse-bias condition, a small leak current flows through the diode. As we keep increasing the reverse voltage it reaches a point where the reverse voltage equals the breakdown voltage. The breakdown voltage is represented as Vz and in this condition the current start flowing in the diode. After the breakdown voltage the current increase drastically unit it reaches a stable value.
In reverse bias condition, two kinds of breakdowns occur for Zener Diode which are,
- Avalanche Breakdown
- Zener Breakdown
Avalanche Breakdown
The phenomenon of Avalanche breakdown occurs both in the ordinary diode and Zener Diode at high reverse voltage. For a high value of reverse voltage, the free electron in the PN junction diode gains energy and acquires high velocity and these high-velocity electrons collide with other atoms and knock electrons from that atoms. This collision continues and new electrons are available for conducting current thus the current increase rapidly in the diode.
This phenomenon of a sudden increase in the current is called the Avalanche breakdown. This phenomenon damages the diode permanently whereas the Zener diode is a specific diode that is made to operate in this reverse voltage area.
If the reverse voltage is greater than 6V the avalanche breakdown happens in the Zener diode.
Zener Breakdown
Zener breakdown happens in heavily doped PN junction diodes. In these diodes, if the reverse bias voltages reach closer to Zener Voltage, the electric field gets stronger and is sufficient enough to pull electrons from the valance band. These electrons then gain energy from the electric field and break free from the atom.
Thus, for these diodes in the Zener breakdown region, a slight increase in the voltage causes a sudden increase in the current.
Zener Diode
Zener Diode is one of the most important semiconductor diodes used in our daily life. It is a specific diode that works in reverse bias conditions. It allows current to flow from anode to cathode and it also works in the reverse direction. Let’s learn about Zener Diodes their function, and their construction, in detail in this article.