What is Diode, Uses, Symbol, Types (Zener, LED, Avalanche, PIN, Schottky)

A diode is made up of two words that is di means two, and ‘ode’ means electrodes which means that a device or component has two electrodes. Diode have two electrodes anode and cathode. Most diodes are made with semiconductor materials such as silicon, germanium or selenium. Anode have a positive charge and cathode have negative charge. Diode is an electrical components that allow the flow of current in only one direction.



Types of Diodes

Zener diode

A diode in which the flow of current is from anode to cathode and cathode to anode defining it has the capacity of conducting in both forward and reverse biases are referred to a zener diode. A form of semiconductor diode in which at a critical
reverse voltage a large reverse current can flow.


A zener diode is a silicon semiconductor device that permits current to flow in either a forward or reverse direction.

Uses of zener diode

Zener diodes are widely used for in electronics equipment of all the kinds and one of the basic building blocks of electronic circuits. They are used to generate low power stabilized supply rails form a higher voltage and to provide reference voltage for circuit especially stabilized power supplies.


Zener diode operate similarly to conventional diodes when in the forward bias mode. They have a bias trun on voltage of between 0.3 and 0.7v. when connected in the reverse mode, there is a small leakage current flow in most applications. Therefore a zener diode is sometimes called a voltage regulator diode for example full wave or bridge rectifier consist of ripples superimposed on a dc voltage.

Light Emitting Diode (LED)

LED is a semiconductor device, which can emit light when an electric current passes through it. To, do this, holes from p type semiconductor recombine with electronics from n type semiconductor to produce light.


A light emitting diode is a two lead semiconductor light source. It is a junction diode that emits when activated when a suitable voltage is applied to the leads, electronics are able holes within the device releasing energy in the from of photons.
When p type such hole move to electron and n type electron move to hole so create a gap it is
call light emit from electron LED emits light by applying a forward current to the pn junction of a
compound semiconductor. When forward current is passed through the light emitting diode,
election and holes move.

Light emitting diode use

The material used most often in LED is gallium through there are many variations on this basic compound, such as aluminium gallium or aluminum photophide.

Advantages of light emitting diode

  • Energy efficiency
  • 60% to 70% improvement in your overall energy efficiency.
  • There are different types of LED technology that are used in light emitting diode DIP, SMD, and COB.


  • Light source- LED are the size of a fleck of papper and mize red, green and blue light emitting is typically used to make white light.
  • Direction- LED emit light in a specific direction, reducing the need for reflection.
  • Heat- light emitting diode emits very little heat.

Avalanche Diode

Avalanche diode is a diode that is designed to experience avalanche breakdown at a specified reverse bias voltage. The is designed to prevent current concentration hot spots, so that the diode is undamaged by the breakdown.


An Avalanche diode is on kind of semiconductor device specially designed to work in the reverse breakdown region. These diode are used as raley valves which are used for controlling the system pressure the voltage. The symbol of this diode is same to as zener diode.

Advantages of avalanche diode

  • Include a greater level of sensitivity.
  • High performance
  • Fast response time


Avalanche diode have a small postive temperature coefficient of voltage, where diodes relying on the zener effect have a negative temperature coefficient. The normal diode allows an electric current in one direction that is forward direction.

PIN Diode

A PIN diode with a wide undoped instrinsic semiconductor region between a p type and an n type semiconductor region. It has an undoped instrinsic semiconductor region between a p type and n type semiconductor.


A PIN diode operate under known as high level injection. In other, the instrinsic region is flooded with charge carriers from the p type and n type regions. It function can be likened to filling up a water bucket with a hole on the side. One the water reaches the hole level it will begin to pour it.

PIN diode advantages

This diode is used in a wide range of areas.
Using for RF switching and The PIN diode structure is useful in photo diodes.

PIN diode Disadvantages

  • Less sensitivity
  • No internal gain
  • Small areas
  • Slow response time
  • High reverse recovery time due to power loss are significant


  • The capacitance of PIN diode is independent of bias level as the net charge is
    used to be very less in the intrinsic layer.
  • PIN diode possess very low reverse recovery time.
  • The diode obeys the standard diode equation for all the low Frequency signals.

Schottky diode

The Schottky diode is a type of metal semiconductor junction diode which
also known as hot carrier diode, low voltage diode or Schottky barrier diode. The Schottky diode
is semiconductor with a metal Schottky diode offers fast switching action and has a low forward

Voltage drop

In a Schottky diode metal replaces the p type semiconductor this metal can range from platinum to molybdenum gold etc. When metal is combined with an n type semiconductor an ms junction is formed.

Advantages of Schottky diode

Faster recovery time
Less noise
Better performance

Disadvantages of Schottky diode

There are some disadvantages a reverse biased Schottky diode will experience a higher level of reverse current than traditional diode. This will ead to more leaked current when connected in reverse.


  • low on state losses
  • Fast switching speed

What is a diode?

A diode is made up of two words that is di means two, and ‘ode’ means electrodes which means that a device or component has two electrodes.

Above mentioned the electronics diode and it’s types. If you have any doubts kindly comment down below.

Also Read about Logic Gates

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