The terminal voltage of the PN junction constitutes a c […]
The terminal voltage of the PN junction constitutes a certain barrier. When the forward bias voltage is applied, the barrier decreases, and the majority carriers in the P and N regions diffuse toward each other. Since the electron mobility is much larger than the hole mobility, a large amount of electrons diffuse into the P region, which constitutes injection of minority carriers in the P region. These electrons recombine with the holes on the valence band, and the energy obtained during recombination is released as light energy. This is the principle of PN junction illumination.