Practice portal › Semiconductor Electronics › p-n Junction Formation
Asked in GUJCET 2025 · Depletion region and barrier potential
Idea: picture the barrier as a hill that a majority carrier has to climb to cross the junction.
Reverse bias puts the battery's positive terminal on the n-side and its negative terminal on the p-side. That pulls electrons away from the junction on the n-side and holes away from it on the p-side.
The depletion region therefore widens, and the uncovered donor and acceptor ion charge inside it grows, so the potential step across the junction becomes larger than the built-in value V₀: it becomes about V₀+V.
With a taller hill the majority-carrier current is choked off, not increased; all that is left is a very small reverse saturation current carried by minority carriers.
So applying a reverse bias raises the potential barrier.
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