What is the depletion region in a PN junction?

The depletion region is the area around a PN junction where free electrons and holes are absent. It forms when electrons from the N-side and holes from the P-side combine near the junction.

This region contains immobile ions and creates an electric field that opposes further charge movement. The depletion region is responsible for the rectifying behavior of a PN junction diode.

Quick Fact: The depletion region acts as a barrier that controls the flow of current across the junction.