Which of the following statement is correct regarding a p-n junction…

The correct answer is Option (3) → The diode current during reverse bias is not much dependent on the applied voltage up to the breakdown voltage.

The behaviour of a p-n junction under bias is decided by how the applied voltage changes the depletion region and the barrier height.

Option (1) During reverse bias, the width of the depletion region decreases. — Incorrect. In reverse bias the applied voltage adds to the barrier, so the depletion region widens.

Option (2) During forward bias, the barrier height increases due to applied voltage. — Incorrect. In forward bias the applied voltage opposes the junction potential, so the barrier height decreases.

Option (3) The diode current during reverse bias is not much dependent on the applied voltage up to the breakdown voltage. — Correct. The reverse current is due to minority carriers and is very small (microamperes); it stays almost constant as the reverse voltage increases until breakdown.

Option (4) A milliammeter is used to measure current in a reverse biased diode. — Incorrect. The reverse current is only of the order of microamperes, so a microammeter, not a milliammeter, is used.

NCERT (2026-27):
p-n Junction Diode Under Reverse Bias – “… The diode reverse current is not very much dependent on the applied voltage. Even a small voltage is sufficient to sweep the minority carriers from one side of the junction to the other side of the junction. … The current under reverse bias is essentially voltage independent upto a critical reverse bias voltage, known as breakdown voltage (V_br).”