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.