When a p-n junction is forward biased, the positive voltage repels holes from the p-region and the negative voltage repels electrons from the n-region, allowing both charge carriers to flow into the depletion region. This causes a current to flow from the positive to the negative region. When reverse biased, the voltages engulf the charge carriers, leaving behind ions and expanding the depletion region to cover the entire p and n regions. As a result, little to no current can flow through the diode.

22. At this biasing condition, the positive potency always repels the holes of the connected p-region.
Similarly the negative voltage repels the electrons from the n-type region. Now both the major
carriers i.e. the electrons and the holes penetrate to the depletion region and arrive their
opposite region. Hence current flows from the positive region to the negative region. When
battery voltage is applied across the junction in the forward bias, a current will flow continuously
through this junction.

23. IS is Saturation Current (10-9 to 10-18 A) VT is Volt-equivalent temperature (= 26 mV at room
temperature) n is Emission coefficient (1 ≤ n ≤ 2 for Si ICs) Actually this expression is
approximated. Reverse Bias of p-n Junction
When a p-n junction is connected across a battery in such a manner that its n-type region is
connected to the positive potency of the battery and the p-type region is connected to the
negative potency of the battery. Now the holes are engulfed by the negative potency of the
battery leaving behind negative static ions in the region and the electrons are engulfed by the
positive potency of the battery leaving behind positive static ions in the region . Ultimately the
depletion region at the p-n junction covers total p and n region of the diode. Hence no current
will flow through this diode.

25. iD drops to zero value or very small value. iD can be written as i0.
IS is Saturation Current (10-9 to 10-18 A) VT is Volt-equivalent temperature (= 26
mV at room temperature) n is Emission coefficient (1 ≤ n ≤ 2 for Si ICs)
Actually this expression is approximated.

27. V-I Characteristics of A P-N
Junction