Virtual Labs

Electrical Properties of pn Junction in Depletion Mode

1. What is the primary assumption made in the depletion approximation for a pn junction?

a: The charge carrier densities are significant within the depletion region. Explanation

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b: The charge carrier densities are negligible within the depletion region. Explanation

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c: The electric field is zero within the depletion region. Explanation

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d: The potential difference is constant within the depletion region. Explanation

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2. What defines the depletion width (W) in a pn junction?

a: The width of the region where the charge carrier densities are zero. Explanation

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b: The width of the region where the electric field is constant. Explanation

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c: The width of the region where the semiconductor is neutral. Explanation

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d: The width of the region where the potential is constant. Explanation

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3. What happens to the electric field within the depletion region of a pn junction?

a: It remains zero. Explanation

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b: It varies linearly. Explanation

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c: It is constant. Explanation

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d: It varies exponentially. Explanation

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4. How does the carrier concentration change outside the depletion region in a pn junction?

a: It remains negligible. Explanation

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b: It is equal to the intrinsic carrier concentration. Explanation

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c: It is equal to the doping concentration. Explanation

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d: It varies linearly. Explanation

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5. In the depletion approximation, what is assumed about the semiconductor outside the depletion region?

a: It is electrically neutral. Explanation

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b: It has a constant electric field. Explanation

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c: It has a constant potential. Explanation

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d: It is fully ionized. Explanation

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6. What is the charge density distribution for an abrupt pn junction?

a: Uniform across the junction. Explanation

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b: Zero in the depletion region. Explanation

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c: A step function changing abruptly at the junction. Explanation

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d: A linear function. Explanation

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7. What is the typical shape of the electric field profile in the depletion region of an abrupt pn junction?

a: Uniform Explanation

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b: Parabolic Explanation

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c: Triangular Explanation

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d: Rectangular Explanation

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8. How is the built-in potential (V_bi) related to the doping concentrations in a pn junction?

a: It is independent of the doping concentrations. Explanation

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b: It decreases with increasing doping concentrations. Explanation

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c: It increases with increasing doping concentrations. Explanation

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d: It varies linearly with the doping concentrations. Explanation

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9. What effect does reverse bias have on the depletion width in a pn junction?

a: It decreases the depletion width. Explanation

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b: It increases the depletion width. Explanation

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c: It does not affect the depletion width. Explanation

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d: It makes the depletion width constant. Explanation

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10. Which parameter is typically used to describe the extent of band bending in a pn junction?

a: Electric field Explanation

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b: Charge density Explanation

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c: Built-in potential Explanation

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d: Depletion width Explanation

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