Q. 123.9( 7 Votes )

Write the two processes that take place in the formation of a p-n junction. Explain with the help of a diagram, the formation of depletion region and barrier potential in a p-n junction.

Answer :

In P type semiconductor concentration of holes is more than

electrons and in N type semiconductor electrons concentration is

more than holes. When P-N junction type of semiconductor is

combined, holes from P side move towards N side and electrons from

n side move towards P side. In between, they collide and neutralize

to from P-N junction.

Thus, near the junction positive charge is built near N side and

negative charge is produced near P side.

This set up a potential difference across junction and from electric

field, E directed from N to P side. This generated electric field is strong

enough to stop further diffusion of majority charge carriers (but, it

helps minority charge carriers to drift across the junction). Either

sides of the junction becomes less dense of charge carriers and

becomes depleted called deletion region. From this point of time,

charge carriers need to overcome this potential barrier developed at

depletion layer.

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