Practice portal › Semiconductor Electronics › p-n Junction Formation
Asked in GUJCET 2026 · Depletion region and barrier potential
Idea: forward bias connects the p-side to the battery's positive terminal and the n-side to its negative terminal, so the applied electric field inside the junction points against the junction's own built-in field.
The net field across the depletion layer is therefore weaker than it was before the battery was connected.
A weaker field across the layer means a smaller potential difference across it: the barrier drops from V₀ to about V₀-V, and the depletion layer narrows at the same time.
That is exactly why a forward biased diode conducts -- with the barrier reduced, majority carriers cross in large numbers and the current climbs steeply with voltage.
So applying a forward bias lowers the potential barrier.
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