Understanding What is Diode and its Types

A semiconductor device that is used for conducting electricity only in one direction is known as a diode. A diode is also known as a rectifier, as it changes alternating current into pulsating direct current. The rating of a diode depends on its type, voltage, and current capacity.

A diode has two terminals, and they are known as anode and cathode. An interesting fact about the diode is that the current passes through it only when a positive voltage is applied to the anode. In this article, let’s understand what is diode along with its construction and working.

What is Diode?

A diode is defined as a two-terminal electrical component that is used for conducting electricity in only one direction. The resistance on one end is higher than the other.

Construction of Diode

For the construction of the diode, semiconductor materials either silicon and germanium, are used. A diode is said to be forward-biased when the anode voltage is more than the cathode voltage. Similarly, when the cathode voltage is more than the anode voltage, it is said to be reverse-biased. Also, a diode symbol has an arrowhead representing the direction of conventional current flow when the diode conducts.

Types of Diodes

The following are the different types of diodes along with their meaning:

  • PN junction Diode

These diodes are also known as rectifier diodes. PN junction diodes are used for the rectification process. One layer of semiconductor is doped with p-type material, while the other layer of semiconductor is doped with n-type material.

  • Light Emitting Diode

The light is produced through the diode when an electric current is passed through the electrodes. LEDs are available in different colours. The colour of the light depends on the energy gap of the semiconductor used.

  • Laser Diode

Laser diodes are different from other types of diodes. It is used in laser devices, DVDs, and CD drives. However, the laser diode has a drawback and that is it has a limited life.

  • Zener Diode

This is the most used diode and is operated in reverse bias condition. To obtain a stable voltage, the passage of current through the resistor should be limited.

  • Photodiode

Even photodiodes work in the reverse bias condition and are used in the detection of light. They are used in solar cells and photometers.

  • Avalanche Diode

The working of the avalanche diode is based on the avalanche effect. This diode is also a reverse-biased diode. For the breakdown to happen in an avalanche diode, the voltage drop should be constant and independent of the current.

  • Schottky diode

The Schottky diode has a lower forward voltage than other silicon PN junction diodes. They are used for obtaining different performances. They are mainly used in rectifier applications.

Characteristics of Diode

The characteristics of a diode are:

  • Forward-biased diode
  • Reverse-biased diode
  • Zero biased diode

Forward-biased Diode

When a diode is in forward-biased condition, there is a small drop in the voltage. For silicon diodes, the forward voltage is 690 mV and for germanium diodes, the forward voltage is 300 mV.

Reverse-biased Diode

When the battery voltage is completely dropped, it is known as a reverse-biased diode. It is -20μA and -50μA for silicon and germanium, respectively.

Zero-biased Diode

When the voltage across the diode is zero, it is known as a zero-biased diode.

Understanding Voltage

The electric potential difference per unit charge between the two points in an electric field is the voltage definition.

Application of Diode

There are different applications of the diode, such as a rectifier. It is also used in logical gates, clamping circuits, and reverse current protection.