Explain the formation of depletion layer and barrier potential in a p-n junction diode.

Formation of depletion region: During formation of p-n junction a hole diffuses from p to n region and electron diffuses from n to p region due to concentration gradient. It leaves behind immobile ions at the junction on both sides. This space charge region at the junction is together called depletion region. Potential Barrier : The immobile ions on p side are negative and on n side are positive. They create a potential difference preventing the further flow of majority charge carriers. This potential is called as barrier potential.