Semiconductor Electronics Materials Devices And Simple Circuits Ques 35

35. Application of a forward bias to a $p-n$ junction

[2005]

(a) widens the depletion zone

(b) increases the potential difference across the depletion zone

(c) increases the number of donors on the $n$ side

(d) increases the electric field in the depletion zone

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Answer:

Correct Answer: 35.(c)

Solution:

  1. (c) Before diffusion

Number of donors is more because electrons from $-ve$ terminal of the cell pushes (enters) the $n$ side and decreases the number of uncompensated pentavalent ion due to which potential barrier is reduced. The neutralised pentavalent atom are again in position to donate electrons.