Reverse Saturation current

            The reverse saturation current which is in general heard in the Electronics subjects has the basic definition taken or derived from the PN junction diode. PN Junction diode is the basic of semiconductor physics  or micro electronics from where the electronic circuits are derived. Reverse saturation current is observed when the PN junction is put under the reverse biasing condition , that is the P type is connected to the negative terminal and the N type is connected to the positive terminal.

             Under this condition the electrons in the N side which are the majority carriers will move away from the PN Junction deeper into the N side, the holes in the P Type which are majority carriers will move to the P side. This makes the area nearer to the junction depleted of the free charge carriers and the depletion region i.e., region free from the free charge carriers will be increased. Now it will become difficult for the charge carriers to cross the increased depletion region.

             If the region is depleted of the free charge carriers then how can the current be available in the reverse bias. In any biasing condition the breakdown of the bonds and creation of the electron hole pairs take place at room temperature. The electron hole pairs that are generated in the depletion regions as bonds are also present in the depletion region, the hole will be pulled towards the  N type as the depletion region of   N- Type contains the donor ions which are positive and the electrons generated will be pulled towards the P type as the region consisting of acceptor ions which are of negative charge, as the electron hole pair formation and recombination takes almost at a constant rate at a given temperature the current also is maintained constant and hence is called the saturation current as this is produced in the reverse bias, this is called as reverse saturation current.