How does a pn junction works?

Answer Posted / arjun_r

When a P-type material and an N-type material are put together, The electrons from N side go to P side and holes from P side go to N side forming a depletion region at the junction. This junction develops a voltage which is dependent on the doping concentration. Now, the free electrons on N-Side require more energy to cross the depletion region. A +Ve voltage applied across the diode(Also called forward bias) can supply this energy.
When a -Ve voltage is applied, it will result in free carriers being pulled away from the depletion region thereby increasing its width. Hence, it will allow the current to pass only in one direction(i.e. when a +ve voltage is applied).

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