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

The diode current during reverse bias is not much dependent on the applied voltage upto the breakdown voltage.

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

Option 1 : “During reverse bias, the width of the depletion region decreases.”. This statement is incorrect because during reverse bias the depletion region actually increases in width. The applied reverse voltage pulls the charge carriers away from the junction, making the barrier region wider.

Option 2 : “During forward bias, the barrier height increases due to applied voltage.” This statement is incorrect because during forward bias the applied voltage reduces the barrier height. This allows charge carriers to cross the junction easily and current starts flowing.

Option 3 : “The diode current during reverse bias is not much dependent on the applied voltage upto the breakdown voltage.” This statement is correct.  When a p-n junction is reverse-biased, the current is driven by the minority charge carriers (electrons in the p-side and holes in the n-side). Because the number of minority carriers is highly limited and depends almost entirely on temperature (thermal generation) rather than the external voltage, this reverse saturation current ($I_0$) remains constant and independent of the applied voltage until it reaches the breakdown threshold.

Option 4 : “A milliammeter is used to measure current in a reverse biased diode.” This statement is incorrect because the reverse bias current is extremely small, usually in microamperes. Therefore, a microammeter is used instead of a milliammeter.