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For a p-n junction the intensity of the electric field is 1×10⁶ V m⁻¹ and the width of the depletion region is 5000 A. The value of the potential barrier is ________ V.

Asked in GUJCET 2019 · Depletion region and barrier potential

Answer: (3) 0.5

Step-by-step solution

Given: E = 1×10⁶ V m⁻¹ and a depletion width w = 5000 A = 5000×10⁻¹⁰ m = 5×10⁻⁷ m.

Idea: inside the depletion layer the field of the uncovered donor and acceptor ions is treated as uniform, so the potential it builds up across the layer is simply V_b = E w.

V_b = 1×10⁶ × 5×10⁻⁷

V_b = 0.5 V, which is the order expected for a silicon junction.

Why the other options are wrong

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