Semiconductor Electronics Materials Devices And Simple Circuits Ques 53
53. The cause of the potential barrier in a $p-n$ diode is
[1998]
(a) depletion of positive charges near the junction
(b) concentration of positive charges near the junction
(c) depletion of negative charges near the junction
(d) concentration of positive and negative charges near the junction
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Answer:
Correct Answer: 53.(d)
Solution:
- (d) During the formation of a junction diode, holes from $p$-region diffuse into $n$-region and electrons from $n$-region diffuse into $p$-region. In both cases, when an electron meets a hole, they cancel the effect of each other and as a result, a thin layer at the junction becomes free from any of charge carriers. This is called depletion layer. There is a potential gradient in the depletion layer, negative on the $p$-side and positive on the $n$-side. The potential difference thus developed across the junction is called potential barrier.
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