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JEE Main 2026 Apr 5 Shift 2, Physics Q20: Semiconductors, p-n Junction Diode and Applications

JEE Main2026Apr 5, Shift 2Physics
Q.

In a semiconductor p-n diode, the doping concentrations on p-side and n-side are atoms/cm and atoms/cm, respectively. Which one of the following statements is true?

  1. A

    Widths of depletion region on either side of the interface are equal

  2. B

    The depletion region width is more on p-side compared to that in n-side

  3. C

    The depletion region width is more on n-side compared to that in p-side

  4. D

    No depletion region forms because of unequal doping concentrations on p and n-sides

Solution

Charge neutrality across the depletion region requires equal charge on both sides:

.

Since (p-side is lightly doped, n-side is heavily doped), the depletion width extends much further on the lightly-doped p-side: .

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