# What is reverse saturation current?

The official page of Wikipedia mentions that reverse saturation current is a part of minority current caused by the drift of charges. I am really confused about this. In class, we have been taught the value of the reverse saturation current using equations of diffusion current.

• A link to the wiki page would help and the equations you were told. – Andy aka Sep 13 '14 at 9:32
• I'm guessing this article, en.wikipedia.org/wiki/Saturation_current. That's bad wording. As you say it is the diffusion of the minority carriers that gives the saturation current. (You can see that in the equation.) In PN junctions we tend to reserve the word drift for the motion of the carriers in the built-in E field of the depletion region. (Someone could change the wiki article.) – George Herold Sep 13 '14 at 12:16

Under reverse polarization, the externally applied voltage V pulls the holes in the the p side and the electrons in the n side away from the junction. The width of the depletion Layer and the height of the barrier increase accordingly.

The increase in the barrier energy is measured in eV. This rise of the barrier height reduces the current to a negligible value, since very few majority carriers can now cross the junction by surmounting the enhanced barrier.

On the other side, the number of minority carriers moving down the potential barrier is left unaffected since this number depends (mostly) on the temperature. As a result of this mechanism, a small current called the "reverse saturation current" flows. The reverse saturation current is almost independent of the applied reverse bias voltage, but increases with the rise of temperature of the junction diode. This is because the minority carrier density contributing proportion increases with the rise of temperature.

• As a rule of thumb, the reverse saturation current for a PN junction doubles for every 10C degrees rise in temperature. – jose.angel.jimenez Dec 14 '15 at 18:23

In a PN junction diode, the reverse saturation current is due to the diffusive flow of minority electrons from the p-side to the n-side and the minority holes from the n-side to the p-side.

Hence, the reverse saturation current depends on the diffusion coefficient of electrons and holes. The minority carriers are thermally generated so the reverse saturation current is almost unaffected by the reverse bias but is highly sensitive to temperature changes

it is a current which is produced due to the small reverse voltage when pn junction diode is reverse biased. in a reverse characteristic of pn junction,current increase in range of nano amp(silicon) or microamp(ger)with respect to reverse voltage .when voltage breakdown occurs,current remains constant and not increase eventhough there is increase of voltage. this current is known as reverse saturation current.

• when breakdown occurs, the current does not remain constant rather it increases rapidly. – nidhin Oct 7 '15 at 7:41