difference between zener diode and pn junction diode

The Difference Between Zener Diode and PN Junction Diode

When it comes to diodes, there are various types that can be used for different purposes. Two of the most common types of diodes are zener and PN junction diodes. Although both diodes share similarities, they have unique features that set them apart.

What is a PN Junction Diode?

A PN junction diode is a semiconductor device that allows current to flow in only one direction. It is created by doping p-type and n-type semiconductors to create a junction between them. As a result, the diode becomes polarized and electrons flow easily in one direction while opposing current in the other direction.

PN junction diodes are widely used in many electronic devices, including power supplies, rectifiers, and signal processing circuits. They are also popular in photovoltaic cells for converting sunlight into electrical energy.

What is a Zener Diode?

Zener diodes are similar to PN junction diodes. They are also semiconductor devices but are designed to operate in the reverse breakdown region. Unlike other diodes, zener diodes are specifically designed to conduct electricity in the reverse direction when a certain voltage is reached. This allows them to regulate voltage levels in electronic circuits.

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Zener diodes are used as voltage regulators in many electronic circuits such as power supplies, protective devices, and overvoltage clamping circuits. They also play an essential role in helping to protect electronic devices against power surges.

The Differences

The main difference between zener diodes and PN junction diodes is their mode of operation. PN junction diodes are mostly used as rectifiers, while zener diodes are mainly used as voltage regulators.

Another difference is the way they conduct reverse current. When a PN junction diode is subjected to reverse breakdown, it is irreversibly destroyed. In contrast, a zener diode conducts reverse current without being destroyed, making it ideal for voltage regulation purposes.


In conclusion, both PN junction and zener diodes have their unique features and are widely used in various electronic devices. Understanding the differences between these two types of diodes is essential in choosing the right diode for specific electronic applications. Whether you need to rectify or regulate voltage, you can be sure that there is a diode that meets your requirements.

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Table difference between zener diode and pn junction diode

Parameter Zener Diode PN Junction Diode
Symbol Zener Diode Symbol PN Junction Diode Symbol
Function Operates in the reverse bias breakdown region and maintains a constant voltage across its terminals. Operates in the forward bias region and allows current to flow in one direction.
Construction Has a heavily doped p-n junction with a sharp depletion region. Has a lightly doped p-n junction.
Breakdown Voltage Fixed and specified by the manufacturer. Variable and depends on the doping concentration of the diode.
Applications Used as a voltage regulator and in voltage reference circuits. Used in rectifier circuits and for signal detection and mixing.