Definition of P N Junction

A p-n junction diode is a juncture or border between two semiconductor material types. These materials are p-type and n-type semiconductors.  The p-side, also known as the positive side of the semiconductor, has an excess of holes and the n-side, also known as the semiconductor’s negative side, has an excess of electrons. The P-N junction is made by the process called doping consisting of the p-type silicon and n-type silicon. When these p-type and n-type materials are placed together in contact, the current will readily flow from one direction and will not flow on the other side of the material. 

What is doping in the P-N junction?

If we use a different type of material or a different type of semiconductor to make the p-n junction, there will be a grain boundary that will refrain the movement of electrons from one side to the another; therefore, we use a process known as doping to solve this problem.

Doping is an intentional procedure carried out during the production of semiconductors. Doping the process of adding impurities to an intrinsic semiconductor (also known as pure semiconductor without any impurities) to modulate its electric, structural and optical properties. Adding dopants atoms can change the nature of semiconductors to conduct electricity. 

When the holes and free electrons attract each other and bond to each other, they disappear near the edge of the semiconductor. This process is known as depletion in the PN junction. 

Depletion in PN junction. 

During the dispersion of the charge carrier across the junction, the electron is transported from the n-side to the p-side of the junction, and at the same time, holes migrate from the p-side to the n-side of the junction. Near the p-type region, there are negatively charged acceptor ions. At the n-type, there are positively charged donor ions which creates a barrier and prevents the flow of the charge across the junction; this is known as depletion in the p-n junction. 

The area where there is no charge is called the depletion region. If there is no presence of depletion region, the charge carriers from n-type will transfer to the p-type, and the efficiency of the p-n junction will decrease. 

P-N junction diode and diode characteristics.

P-N junction diode and diode characteristics have crucial importance in modern electronics. Because of the depletion region, p-n junctions diodes are commonly used as diodes. Diodes characteristics, are elements that allow the flow of electricity in one direction and stop in the other direction. Bias is the application of a voltage in the p-n junction diode. There are two types of bias.

1. Forward bias
2. Reverse bias

Forward bias in the p-n junction.

In forward bias, the negative side is connected with the n-side, the positive side is connected with p-type, and a current source is applied. Because of the opposite applied voltage, most of the carries flow through the junction. 

Reverse bias in the p-n junction.

In reverse bias, the positive side is connected to the n-side, the negative side is connected top-side, and a current is applied. Because of this, the electrons drift towards the junction and integrate with the holes and create positive impurity ions, and the thickness of the layer increases.

The pn junction integrated circuit.

Integrated junction was invented in 1947 by William B. Shockley. Integrated circuits are also known as microelectronic circuits, as the circuits were fabricated in a single unit. In 1958 Jack Kilby thought of reducing the size of the circuit. They made narrow paths of metal and laid on the material device. These small paths acted as wires, and this technique could be known as an integrated circuit on a single piece of solid material, and this is how the integrated circuit was discovered.  

Conclusion 

A P-N junction is a juncture between two semiconductors material types. The p-type and n-type are the two types of semiconductors. Doping is an intentional procedure carried out during the production of semiconductors. It is a process where impurities are added to the semiconductor to modulate the material. When the holes and free electrons attract each other and bond, they disappear near the edge of the semiconductor. This process is known as depletion. There are two types of bias forward and reverse. In forwarding bias n-side is connected to the negative, and the p-side is connected to the positive side. Reverse bias is the opposite of the forward bias.