Question: Q. 6. Explain the two processes involved in the formation of a $p-n$ junction diode. Hence define the term ‘barrier potential’.
U] [Delhi I, II, III Comptt. 2017]
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Solution:
Ans. Explanation of two processes 1+1 Definition of barrier potential
1 Diffusion : It is the process of movement of majority charge carriers from their majority zone (i.e., electrons from $n \rightarrow p$ and holes from $p \rightarrow n$ ) due to the electric field developed at the junction.
Drift : Process of movement of minority charge carriers (i.e., holes from $n \rightarrow p$ and electrons from $p \rightarrow n$ ) due to the electric field developed at the junction.
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Barrier potential : The loss of electrons from the $n$-region and gain of electrons by $p$-region causes a difference of potential across the junction, whose polarity is such as to oppose and then stop the further flow of charge carriers. This (stopping) potential is called Barrier potential.
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