Difference Between PN Junction & Zener Diode

Difference Between PN Junction & Zener Diode

The major difference between PN junction and the Zener diode is that the PN junction diode allows current to pass only in the forward direction, whereas the Zener diode allows the current to flow both in the forward and the reversed direction. The other differences between the PN-junction and Zener diode are shown in the comparison chart.

The PN junction diode is used for rectification purpose because it allows the current to flow only in one direction. It is a type of switch which only allows the forward current to pass through it. On the other hand, the Zener diode allows both the forward and reverse current to pass through it. The Zener diode is used as a voltage regulator in the electronic circuit because it provides the constant voltage from the supply to the load whose voltage vary over sufficient range.

Comparison Table

Key Differences Between PN-Junction and Zener Diode

The following are the key differences between the PN junction and Zener diode.

1. The semiconductor which conducts only in one direction is known as the PN-junction diode. And the Zener diode is the silicon diode which is optimised to operate in the breakdown region.
2. The reverse current flow through the diode damage the PN-junction diodes. The reverse current flows through the diode when it is connected in reverse biased. The reverse biasing means the p-type material is connected to the negative terminal of the supply and the n-type material is connected to the positive terminal of the supply. But the Zener diode allows the current to pass through both the direction.
3. The doping level of the PN-junction diode is low as compared to Zener diode. The width of the depletion region depends on their doping level. If the doping level of the diode is high,  their depletion region is low and vice versa.
4. The breakdown in PN-junction diode occurs at high voltage level, whereas in PN-junction diode it occurs at low voltage levels. The breakdown is the phenomenon of making the depletion region conductive. The heavily doped diode has a low depletion region.
5. The PN-junction obey the ohm’s law whereas Zener diode does not obey the ohms law. The ohms law said that the voltage applies across the diode is equal to the product of the current and resistance applied across the diodes.
6. The PN-junction diode is mainly used for rectification purpose, whereas the Zener diode is used for providing the constant voltage to the load whose voltage vary.