Question

Write the names of two important processes which occur on formation of p-n junctions. Define the 'depletion region' and 'potential barrier' in it.

Answer 1

The two major steps involved in the formation of the P-N junction. Diffusion and drift are the terms used to describe them. The diffusion current and the drift current are produced in these processes, respectively. They're also going in separate directions. The voltage regulator ensures that a circuit's voltage remains constant.

Complete Step By Step Answer:
These are the following two important processes on the formation of p-n junctions.
A. The bulk of charge carriers will diffuse from a greater concentration to a lower concentration when the P and N sides come into touch. This causes electrons to travel from the N to the P junction, where they are mixed with holes near the junction. Similarly, holes will flow from the P side to the N side of the junction and join with the electrons. As seen in the diagram, the region around the connection becomes depleted of carriers and charged as a result of this. Diffusion current refers to the movement of charge carriers. An electric field is created by the charge in the depletion region. The passage of minority charge carriers over the depletion region will be caused by this electric field. The drift current is what it's called. Both the diffusion and drift currents are going in the wrong direction. When they are in equilibrium, they are equal to one other, resulting in the formation of the P-N junction.
B. The device utilised as a voltage regulator is the Zener diode. When an unregulated voltage is applied to a Zener diode with the addition of a series resistor, the Zener diode is reverse biased. When the input voltage is increased, the current and resistance via the Zener diode rise as well. As a result, without the variation in voltage drop over the Zener diode, the voltage drops over resistance are likewise increased. This is owing to the fact that the Zener voltage remains constant regardless of the current in the breakdown zone. When the input voltage is dropped, the voltage and current in the resistance are reduced as well, without changing the Zener diode voltage.
Depletion region:
Due to the concentration difference, a hole diffuses from p to n, leaving behind a negative charge that is stationary. On the p-side of the junction, a layer of negative charge develops as the holes continue to spread. Because the electrons and holes involved in the initial movement across the junction depleted the region of their free charges, this space-charge region on either side of the junction is referred to as the depletion region.
Potential barrier:
The potential barrier in a p-n junction is a form of barrier that prevents normal charge flow across the junction; this resistance to charge flow is known as barrier potential.

Note:
Voltage control is aided by Zener diodes. Surge suppressors, switching processes, and clipper circuits are all applications for them. They're also employed as a source of information. They can also be employed in the correction procedure. As a result of the presence of a potential barrier, no free charge carriers can rest, and the regions on either side of the junction are completely depleted of free charge carriers when compared to materials of the N and P types further away from the junction; this area around the p-n junction is now known as the depletion layer.