CBSE Class 12 · 2020 · SemiconductorsShort Answer

The depletion layer is the narrow region near the junction that has only immobile ions and no mobile carriers; the potential difference set up across it by these ions is the potential barrier.
Under forward bias the applied voltage opposes this barrier field.
(a) Majority carriers are pushed towards the junction and neutralise some ions, so the depletion width decreases.
(b) The effective barrier $(V_B-V)$ falls, so the value of the potential barrier decreases.
$\boxed{\text{Forward bias}\Rightarrow \text{both width and barrier decrease.}}$