When a PN junction is forward biased, the current in the external wires is

When a PN junction is forward biased, the current in the external wires is

Right Answer is:

By free electrons

SOLUTION

When a PN junction is forward biased, the current in the external wires is by free electrons.

  • Whenever a PN junction is forward biased, the holes are repelled by the positive terminal of the voltage source. Then holes are forcefully moved towards the junction.
  • Correspondingly, the electrons are repelled by the negative terminal of the voltage source and these electrons are also forcefully moved towards the junction.
  • As carriers (holes and electrons) get energy from the external voltage source, some of the holes and electrons are able to enter into the depletion layer and recombination takes place.
  • The current in the p-region is due to the movement of holes that are the majority carriers. This is the hole current.
  • While the current in the n-region is due to the movement of free electrons which are majority carriers. This is the electron current.
  • Hence the overall forward current is due to me majority charge carrier. These majority carriers can then travel around the closed circuit and relatively large current flows.

  • Therefore, the current flowing through the PN junction is the sum of electron diffusion current in the N-type region and hole diffusion current in the P-type region.
  • Though the total current inside the semiconductor is due to free electrons and holes, the current in the external wire is fully by electrons.
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