This region is also known as the depletion region.

Once the voltage is applied then the LED will forward biased, so the electrons in the N-region and holes from P-region will move to the active region.

When the voltage is not applied to the LED, then there is no flow of electrons and holes so they are stable. In the construction, the P-type region includes the holes the N-type region includes elections whereas the active region includes both holes and electrons. The three regions of semiconductor material can be observed in the construction.

These three layers are arranged one by one where the top region is a P-type region, the middle region is active and finally, the bottom region is N-type. The construction of LED is very simple because it is designed through the deposition of three semiconductor material layers over a substrate.

The LED includes two terminals namely anode (+) and the cathode (-). The LED symbol is similar to a diode symbol except for two small arrows that specify the emission of light, thus it is called LED (light-emitting diode).

How the led light works