Explain the terms depletion layer

Explanation

Depletion region: It is a region created around the p-n junction which is devoid of free charge carriers and has immobile ions. When a p-n junction is formed by bringing P-type semiconductor into a close contact with N-type semiconductor, the diffusion of majority carriers across the junction takes places due to difference in concentration of the charge carriers in the two sections of p-n junction, When an electron diffuses from N-region to P-region, it combines with the hole in P-region forming electron-hole combination. Due to which N-region will have ionised donor atom and P-region will have ionised acceptor atom which are immobile. As a result of which an electric field is set up across the junction as if a fictitious battery is connected to the P-region. This electric field opposes the migration of free charge carriers across the junction. In the vicinity of the junction, a region is created which is devoid of free charge carriers and has immobile ions. This region is called depletion region.