What is Diode? Types, Symbols and Applications of Diode

Diode Definition, Types, Symbol, and Applications

What is Diode | Types, Symbols and Applications of Diode


You are all may be heard about Diode. The diode is a very important component or device in electronics engineering. There are many application and types of the diode. In this post, we are going to know the working principle, types, and applications of Diode.




What is a Diode?

A diode is an electronic component having two terminals or two electrodes which allows the flow of current in one direction or both direction. 
Most of the diodes allow the flow of current in one direction but some diodes like Zener Diode allow the flow of current in both directions.


Diode Materials:

Most of the diodes are made by semiconductor materials like Silicon, Germanium, Selenium, gallium arsenide etc.
In earlier days the diodes are made up with vacuum tubes.


Types of Diodes:

There are many types of Diode. Important types are given below,

  1. PN Junction Diode
  2. Zener Diode
  3. Light Emitting Diode(LED)
  4. Schottky Diode 
  5. Photodiodes

Let's talk something about PN Junction Diode:

The most important and wide usable diode is PN Junction Diode. The applications of PN Junction diodes are larger than other diodes. In most of the electronic circuits, the PN Junction diodes are used.



PN Junction diode



The PN Junction diode is very simple in construction. A P-type and an N-type semiconductor material is attached together. The terminal from P-types material is called Positive terminal or Anode and the terminal from N-type material is Negative terminal or Cathode. The place the P-type and N-type is called depletion region as in that place no charge carrier exists. 

The PN Junction Diode allow the flow of current in one direction only positive to negative. For the operation of PN Junction diode, it should be connected in Forward Bias that means the P terminal of the diode should be connected with positive terminal of the source and the N terminal of the diode should be connected with the negative terminal of the source or battery.


Why PN Junction Diode allow the flow of current in one direction only?


When we connect the cathode or negative terminal of the diode to the positive terminal of the battery and the anode or positive terminal of the diode with the negative terminal of the battery then it is called that the diode is connected in Reverse Bias. In Reverse bias condition, the diode does not allow the flow of current because,
As the negative terminal of the battery is connected to the positive or P terminal of the diode so the holes are attracted from the P side of the diode to the negative terminal of the battery. On the other hand, as the positive terminal of the battery is connected to the negative or N terminal of the diode so the electrons are attracted from the N side of the diode to the negative terminal of the battery.
Therefore the depletion region will be increased and it will oppose the flow of current.



Diode in reverse bias



Characteristics of an Ideal PN Junction Diode:

The characteristics of an ideal PN Junction diode is, It acts as a good conductor when forward bias and act as a good insulator when reverse bias.


Symbol and Application of PN Junction Diode:

PN Junction diode symbol

  1. PN Junction diodes are used in rectifier circuit to convert AC to DC
  2. PN Junction diodes are used in Inverter circuit as Freewheeling Diode.
  3. The PN Junction diodes are used in Radio demodulation circuit.
  4. PN Junction diodes are used in voltage controled oscillator circuits.

Application and Symbol of Zener Diode:

Zener diode symbol


  1. The main application of Zener Diode is in DC Circuit as a Voltage regulator.
  2. The Zener diodes are used in Crowbar Circuit



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What is Diode? Types, Symbols and Applications of Diode What is Diode? Types, Symbols and Applications of Diode Reviewed by ETechnoG on 09:33 Rating: 5
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