Zener Diode

Introduction 

Before we go into the details of the Zener diode, let’s understand what it is. The Zener diode is a semiconductor device that aids in the current flow in the forward or backward direction. The main speciality of this diode is: it is doped heavily. It also consists of a p-n junction that forms the backbone of this device. In a 4733a Zener diode voltage, the current flow is both in the forward and reverse direction. It is one of the most important electronic devices that partially and not comprehensively conduct electricity. 

What is Zener Diode?

As discussed earlier, it is a device that conducts electricity partially. It is a semiconductor of electricity. The main objective of this device is to make the current flow in the reverse direction. It can be done after a certain threshold of voltage is achieved. However, in a 4733a Zener diode voltage, a standard p-n junction is present. 

This voltage at which the Zener diode starts conducting the electricity in the reverse direction is known as reverse-breakdown voltage. This is the reason why Zener diodes as voltage regulators work wonders. Even in the reverse bias, the voltage tends to remain constant. Moreover, when the voltage drop occurs, the voltage remains constant no matter the amount of voltage being applied. It finds application in Zener diodes as voltage regulators. 

Zener Diode: Working

If we consider the circuit diagram of the Zener diode, we’ll see the diode works in reverse bias. The positive terminal of the diode is connected to the n-type material. Likewise, the p-type material is connected to the negative terminal of the diode. Since the diode is heavily doped, the layer of depletion present in the diode is very thin. The semiconductor material does the doping.  

How does the Zener Diode work? 

The Zener Diode is heavily doped. It means that many impurities are added so that it becomes more conductive. This also means that the depletion layer is extremely thin. Due to heavy doping, the intensity by which the electricity is conducted across the depletion region increases. 

There are two conditions in which we can understand the working of the Zener diode. 

• When there is an absence of any kind of bias in the Zener diode, no current flows through the diode. The electrons continue to be in the valence band of the p-type material. The valence band electrons move from one band to the other.
• In the second condition, the reverse bias is applied. At that, the Zener voltage becomes equal to the supply voltage. Now, it starts conducting electricity in the reverse direction. When the depletion region completely disappears, it is called the Zener Voltage. 

The flow of current occurs because the intensity of the electric field increases across the depletion region. The current flow occurs because the electrons move from the valence band to the conduction band. It initiates the flow of current. The barrier that separates the p-type and n-type material decreases ultimately. At last, the depletion region disappears, and conduction begins. 

Characteristics of Zener Diode 

The characteristics of the Zener diode can be explained below:

We already know that the Zener diode behaves like a normal one when connected in the forward bias. However, the reverse voltage increases when the reverse bias is applied to the diode. Due to this, the reverse voltage goes beyond the set limit. At such a time, the voltage breakdown takes place. This is the Zener breakdown. 

Now that the Zener breakdown has taken place, the current starts conducting in the opposite direction. Several disturbances take place, which makes the current vs. voltage graph haphazard.

Now, the voltage across the Zener diode can be represented by: 

V = VZ + IzRz 

What are the Applications of the Zener Diode? 

The Zener Diode has many applications in the world of physics. As discussed earlier, a Zener regulated power supply serves various purposes. Some of them are discussed below: 

• Zener Diode as A Voltage Stabiliser 

You may have seen that voltage fluctuations can cause a lot of damage to your electrical and commercial appliances. The simple solution to it all is: using a Zener diode. Zener diodes as a voltage regulator are used in all electrical appliances. It provides a steady and constant voltage from the source. 

• Zener Diode for Protection of Metres: Accidental electricity overload can be extremely dangerous. Zener diodes are used in multimeters to prevent such accidents and ensure safety. The connection of the diode to the metre is parallel. When an accidental case of overload occurs, most of the current is passed on to the diode. Hence, it doesn’t cause any damage to the metre in a Zener generated power supply. 
• Zener Diode for Wave Shaping: The Zener Diode is also used to convert the sine wave into the square wave. Now, you may wonder how? The Zener Diodes are connected to a series. Further, they’re connected but in opposite directions. 

Zener voltage is less than the applied voltage in a Zener regulated power supply. Due to this, the diode has high resistance. When the voltage is more than the Zener voltage, it offers low resistance and the current starts flowing through the diode now. There is a drop of voltage at the resistance and cutoff of the input wave at its peak. Henceforth, we see the square wave. 

Conclusion 

Zener Diode is one of the most essential devices of Physics. It finds significant applications in all commercial and industrial equipment. Its ability to resist the voltage and prevent damage due to voltage overload works wonders in the case of heavy and costly equipment. The application of Zener diodes as a voltage regulator helps in the stabilisation of the voltage and ensures a constant flow of voltage across the circuits. This is due to the use of heavy doping, i.e. use of impurities. The application of reverse bias makes the current flow in the opposite direction, and that’s how it’s used in all the appliances.