Working of Zener Diode – Characteristics, Applications

A special diode. Which is capable of allowing current to pass from anode to cathode. However, the most unique feature about this diode is it will allow current to flow in the reverse direction, unlike other diodes. And this is one of the main reasons, the Zener Diode is actively used in different types of semiconductors. Furthermore, the Zener Diode is also known as a Breakdown diode, mainly because it consists of a heavily doped semiconductor, which has the ability to operate in the reverse direction.  

In experimental form, when the terminals connected to the diode are reversed, then the voltage flow in the diode is also reversed, which in turn will result in the effect known as Zener Effect. According to this effect, if the voltage passing in the reverse direction reaches its potential, known as the Zener Potential, then it will lead to a complete breakdown of the junctions. 

Zener Diode Circuit Diagram

 

From the above diagram, the flow of the current and the voltage in a certain direction can be discovered. And when the voltage is reversed, and the terminals are changed, then the voltage is slowly increased to reach the Zener potential, then the individuals can observe the complete breakdown of the diode, due to the Zener effect. 

Types of Breakdowns in Zener Diode

Now that we have covered basic details on how the Zener diode as voltage regulator works, and how the Zener effect is created. Let us talk about the different types of breakdowns that are commonly observed in the Zener Diode.

Zener Breakdown such as,

• Zener Breakdown
• Avalanche Breakdown

Avalanche Breakdown

This kind of phenomenon is observed in both normal diodes as well as Zener diodes at potentially high reverse voltage, especially when it is forward-based. However, with the passage of current through, there will be a small leak, which will flow directly through the diode during the reverse mode. Moreover, the increased voltage in the diode will cause the electrons to accelerate at high velocities.

Besides, the free electrons will continue to collide with the electrons, which in turn will increase the electric current in the diode, leading to a breakdown. However, unlike the normal diode, which will be generally destroyed, this diode is capable of handling the current spike. Apart from this, avalanche breakdowns can also be observed in Zener diodes, when the voltage applied is much greater than 6v.

Zener Breakdown

As you already know from the above sections, the Zener breakdown occurs in the Zener diodes, when the Zener effect is observed. So, in theory, when the applied reverse voltage is increased, the depletion region will expand, which causes electrons to get expelled from the band. And with the increase in the number of electrons getting expelled, the electric current will rise rapidly.

VI Characteristics of Zener Diode

The above graph will explain in detail how the Zener breakdown occurs in the Zener Diodes, and how the parameters such as reverse bias, forward bias, and current have an influence on the breakdown. 

Application of Zener Diode

There are multiple applications of the Zener diode, that are actively used such as,  

• Zener Diode as Voltage Regulator: In order to regulate the voltage across small loads, such as a Shunt Voltage regulator. 
• Clipping Circuits: To limit the parts of one or both cycles in the AC Waveform, modified clipping circuits are used. 
• Over-Voltage Protection: So, as you know the Zener diode has the ability to resist the breakdown due to a short circuit, due to rising voltage in the said circuit. 

Conclusion

The above article would help you understand all about the working of Zener Diode, in more detail with the diagram. So, if you have trouble understanding any other complex topics, in the subject. Then it would be a good option for you to enroll in the Online Interactive Classes offered by the Tutoroot platform. Mainly because the students will get access to the best study guides, expert staff, constant online revisions, doubt clearing sessions, and much more. 

Frequently Asked Questions

Why is Zener Diode used as a regulator? 

The Zener Diode is used as a regulator, because the voltage drop across the diode is constant, which in turn reduces the chances of the breakdown.