Consider the following statements about a p-n junction diode under forward bias:
(A) Electrons from the n-side cross the depletion region and reach the p-side, where they are minority carriers.
(B) The injected electrons on the p-side diffuse from the junction edge towards the other end of the p-side.
(C) The total forward current of the diode is usually of the order of microampere.
(D) The applied voltage drops mostly across the p-side and the n-side of the junction.
Which of the above statements are incorrect?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → (C) and (D) only
A forward bias lowers the barrier. Carriers then cross the junction and enter the other side as minority carriers. This process is called minority carrier injection.
(A) Electrons from the n-side cross the depletion region and reach the p-side, where they are minority carriers. — Correct statement. Electrons are the majority carriers of the n-side. After crossing, they are minority carriers on the p-side.
(B) The injected electrons on the p-side diffuse from the junction edge towards the other end of the p-side. — Correct statement. The injected electrons pile up near the junction edge. This concentration gradient makes them diffuse towards the far end of the p-side.
(C) The total forward current of the diode is usually of the order of microampere. — Incorrect statement. The forward current is usually of the order of milliampere. Currents of the order of microampere flow in reverse bias.
(D) The applied voltage drops mostly across the p-side and the n-side of the junction. — Incorrect statement. The depletion region has a much higher resistance than the p-side and n-side. So the applied voltage drops mostly across the depletion region.
NCERT (2026-27):
p-n junction diode under forward bias – “Due to the applied voltage, electrons from n-side cross the depletion region and reach p-side (where they are minority carries).”
p-n junction diode under forward bias – “Due to this concentration gradient, the injected electrons on p-side diffuse from the junction edge of p-side to the other end of p-side.”
p-n junction diode under forward bias – “… The magnitude of this current is usually in mA.”
p-n junction diode under forward bias – “The applied voltage mostly drops across the depletion region and the voltage drop across the p-side and n-side of the junction is negligible.”