We all think that resistors, capacitors, conductors, and insulators are the basic elements of an electrical circuit. However, most of the electrical magic takes place because of the presence of the semiconductors. The basic semiconductor which we are aware of is known as the diode.

What Is A Diode?

We know that the definition of the diode is it is a two-terminal device that conducts electricity in one direction. The two terminals are known as anode and cathode. The current flows from anode to cathode and this property of the diode is used in its applications. We shall also learn about different types of diodes along with their applications.

Construction Of Diode

The construction of the diode is done with a p-type semiconductor and with an n-type semiconductor. When these two semiconductors are joined together, they form a layer which is known as the depletion layer. This layer is formed because of the presence of the excess electrons and excess holes. This layer is broken down by the passage of the electric current.

Forward Biased Condition

The diode is said to be in a forward-biased condition when a positive voltage is applied to the anode and negative voltage is applied to the cathode. There is a breakdown in the depletion layer when the diode is forward biased allowing the flow of current from anode to cathode. The minimum voltage which is required to conduct the diode in the forward direction is known as the forward breakdown voltage.

Reverse Biased Condition

The diode is said to be in a reverse-biased condition when a negative voltage is applied to the anode and a positive voltage is applied to the cathode. When the diode is working in the reverse biased condition, the flow of holes increases in the diode which results in no flow of current.

VI Characteristics Of A Diode

When we talk about the VI characteristics of a diode, we usually refer to the PN junction diode. PN junction diode is considered to be the standard model of a diode. The VI characteristics of PN junction diode could be used for understanding the voltage-current relationship in a diode.

The representation of the VI characteristic can be done on the x-y plane. The x-axis represents the voltage applied while the y-axis represents the current flowing through the diode. Forward biased current, forward-biased voltage, reverse-biased saturation current, and reverse-biased current of the diode are the common terminologies that are used.

Types Of Diodes

There are different types of diodes that are available in the market, and they are Schottky diode, tunnel diode, Zener diode, PIN diode, LED, laser diode, PN junction diode, photodiode, and varactor diode.

  • Schottky diode: This diode has a lower forward voltage drop and is used in radio frequency applications, rectifiers, and clamping diodes.
  • PN junction diode: This diode is considered to be the basic diode and is used in applications that use small signal ranges.
  • PIN diode: The characterization of the diode is based on its construction. This diode finds applications in switching as it has a depletion region which is favorable for switching.
  • Photodiode: This diode is used for detecting the light. The working condition for a photodiode is based on the reverse biased condition. Photodiodes can also be used in the production of electricity.

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