What is depletion barrier?

Explanation

Due to diffusion of charge carriers in p-n junction, the number of electron decreases in the n-section and the number of electron in p-section increases so that potential difference across junction is developed.
The polarity of this potential is such as to oppose further flow of carriers so that a condition of equilibrium exists.

Figure shows the p-n junction at equilibrium and the potential across the junction.
The n-material has lost electrons and p-materials has acquired electrons.
This potential tends to prevent the movement of electron from the n-region into p-region it is called a barrier potential. This barrier is obtained in the depletion region, hence it is also called depletion barrier.