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CBSE Class 12 · 2011 · All India · SemiconductorsVery Short Answer

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What happens to the width of depletion layer of a p-n junction when it is
(i) forward biased,
(ii) reverse biased?

Answer: (i) In forward bias the depletion width decreases;
(ii) in reverse bias it increases.

Solution

The external field adds to or opposes the junction barrier field.
(i) Forward bias opposes the barrier field, carriers move towards the junction and neutralise ions, so the depletion width decreases.
(ii) Reverse bias aids the barrier field, carriers are swept away exposing more ions, so the depletion width increases.

CBSE Class 12 Board · 2011 · All India · Subjective

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