Choose the correct statements about a p-n junction diode:
(A) Diffusion current is due to the movement of the majority charge carriers.
(B) Drift current is due to the movement of minority charge carriers.
(C) Diffusion and drift currents are both due to majority charge carriers.
(D) The internally developed electric field in a p-n junction diode across the depletion region is always from n side to p side of semiconductor.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → (A), (B) and (D) only
At a p-n junction, diffusion is driven by the difference in concentration and drift by the electric field in the depletion region.
(A) Diffusion current is due to the movement of the majority charge carriers. — Correct. Holes diffuse from p to n and electrons from n to p, each from the side where it is the majority carrier.
(B) Drift current is due to the movement of minority charge carriers. — Correct. The junction field sweeps minority carriers across.
(C) Diffusion and drift currents are both due to majority charge carriers. — Incorrect. The drift current is due to minority carriers.
(D) The internally developed electric field in a p-n junction diode across the depletion region is always from n side to p side of semiconductor. — Correct. Diffusion leaves positive donor ions on the n-side and negative acceptor ions on the p-side, so the field points from n to p.
NCERT (2026-27):
p-n Junction Formation – “… During the formation of p-n junction, and due to the concentration gradient across p-, and n- sides, holes diffuse from p-side to n-side (\( p \rightarrow n \)) and electrons diffuse from n-side to p-side (\( n \rightarrow p \)). This motion of charge carries gives rise to diffusion current across the junction. … Due to the positive space-charge region on n-side of the junction and negative space charge region on p-side of the junction, an electric field directed from positive charge towards negative charge develops. Due to this field, an electron on p-side of the junction moves to n-side and a hole on n-side of the junction moves to p-side. The motion of charge carriers due to the electric field is called drift.”