PN JNCTION DIODE UNDER REVERSE BIAS

1.When the pn junction is reverse biased the negative teriminal attracts the holes in the p region, away from the junction.

2.The positive terminal attracts the free electrons in the n region away from the junction.

3.No charge carrier is able to cross the junction.As electrons and holes both move away from the junction, the depletion region widens.

4.As depletion region widens, barrier potential across the junction also increases.

5.The positive side drags the electrons from p region towards the positive of battery.Similarly negative side of barrier potential drags the holes from n region towards the negative of battery.

6.The electrons on p side and holes on n side are minority charge carriers,which constitute the current in reverse biased condition.Thus reverse conduction takes place

7.The reverse current flows due to minority charge carriers which are small in number.Hence reverse current is always very small.This reverse current is called reverse saturation current.