The reverse biasing in a p-n junction diode

The correct answer is Option (2) → increases the potential barrier height

In reverse bias the p-side is joined to the negative terminal and the n-side to the positive terminal. The applied voltage then acts in the same direction as the barrier potential, so the effective barrier becomes \( V_0 + V \) and the depletion layer widens.

Option (1) decreases the potential barrier height — Incorrect. The barrier height decreases in forward bias, where the applied voltage opposes the barrier potential.

Option (2) increases the potential barrier height — Correct. The applied voltage adds to the barrier potential, so the barrier becomes higher.

Option (3) decreases the number of minority charge carriers — Incorrect. The number of minority carriers is set by temperature (thermal generation), not by the bias.

Option (4) increases the number of majority charge carriers — Incorrect. The number of majority carriers is fixed by the doping; reverse bias only pulls them away from the junction.

NCERT (2026-27):
p-n Junction Diode Under Reverse Bias – “When an external voltage (V) is applied across the diode such that n-side is positive and p-side is negative, it is said to be reverse biased [Fig.14.15(a)]. The applied voltage mostly drops across the depletion region. The direction of applied voltage is same as the direction of barrier potential. As a result, the barrier height increases and the depletion region widens due to the change in the electric field.”