Question

In the case of forward biasing of a p-n junction diode which one of the following figures correctly depicts the direction of the conventional current.
A.

B.
C.
D.

Answer 1

A p-n junction is defined as a two-terminal or two electrode semiconductor device that allows the electric current to flow in one direction and opposes the current in the opposite direction. When the p-n junction is forward biased, it will allow the electric current to flow. On the other hand, when the p-n junction is reversed biased, it will oppose the current flow.

Complete answer:
- When a p-n junction is forward biased the p-type semiconductor connects to the positive terminal of the battery and the n-type connects to the negative terminal of the battery.
- When the battery is connected with the positive terminal connected to the p-type and negative terminal connected to the n-type, the depletion layer starts decreasing. This is because the positive terminal of the battery repels the holes in the p-type and the negative terminal of the battery repels the electrons in the n-type. The potential difference between the p-type and the n-type decreases that results in the decrease of the depletion layer of the p-n junction diode.
- Therefore, the conventional current in the p-type will be towards the n-type and the direction of current in the n-type will be towards the p-type. This is because holes in p-type and electrons in n-type attract each other.

So, the correct answer is “Option C”.

Note:
In the case of forward biasing of the p-n junction, the applied electric field and the built-in electric field will be opposite to each other. When we will add both the electric fields, the magnitude of the resultant electric field will be less than the built-in electric field. As a result of this, the resistance will be less and the depletion layer will become thin.