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The increase in the width of the depletion region in a p-n junction diode is due to

Asked in NEET 2020 · Depletion region and barrier potential

Answer: (1) reverse bias only

Step-by-step solution

Idea: the depletion region is as wide as it needs to be to support the potential across the junction.

Reverse bias adds to the built-in potential, so more potential has to be supported.

That calls for more uncovered ionised impurities on each side, which means the region of uncovered charge extends further into both the p and n material.

Forward bias does the opposite, cancelling part of the built-in potential and letting the region shrink.

So the width increases under reverse bias only.

Why the other options are wrong

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