When p - n junction diode is forward biased then

both the depletion region and barrier height are reduced

the depletion region is widened and barrier height is reduced

the depletion region is reduced and barrier height is increased

both the depletion region and barrier height are increased

Electronic Devices PYQ — JEE Main 2004 · Shift 0 · Q127 with Solution

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Correct answer: A

Forward bias in a $p$ - $n$ junction

In forward bias:
- the $p$ -side is connected to the positive terminal,
- the $n$ -side is connected to the negative terminal.
This applied voltage opposes the built-in electric field of the depletion region.
Effect on barrier potential

The junction already has a built-in potential barrier due to diffusion of charge carriers. When forward bias is applied, the external voltage reduces this barrier.

So, the barrier height decreases.
Effect on depletion region width

Since the barrier is reduced, majority carriers can cross the junction more easily. The immobile ion region near the junction shrinks.

So, the depletion region width decreases.
Check the options
- A: both the depletion region and barrier height are reduced ✅
- B: depletion region widened, barrier height reduced ❌
- C: depletion region reduced, barrier height increased ❌
- D: both increased ❌
Derived answer

Therefore, the correct option is: $\boxed{A}$
Comparison with stored correct answer

Stored correct answer is A, which matches the derived answer.