Question

Explain how a potential barrier is developed in a p-n junction diode.

Answer 1

1. Since the grain boundaries of semiconductors do not allow the movement of electrons, impurities must be added to the material, a process called doping.
2. The doping process is a process in which a small part of a p-type semiconductor is added with a pentavalent impurity, and then the small part is changed to a p-type semiconductor and another part is changed to an n-type semiconductor by adding a trivalent impurity. Both P-type semiconductors and n-type semiconductors are contained in the same silicon material.
3. There is a high concentration of holes in the P-region and a high concentration of electrons in the N-region
4. After the formation of the p-n junction, the phenomenon of diffusion and drift occurs. Diffusion is the process of mixing holes and electrons, and drift is the phenomenon of charges colliding with each other.
5. When holes move in the direction of electrons, a layer of electrons is formed on the p-type side, a layer of holes is formed on the n-type side, and a region called the depletion layer in which this depletion layer is involved is formed.
6. This depletion layer forms a field in the opposite direction of the motion of electrons thereby opposing the process of drifting
7. When the depletion layer stabilizes there is a potential barrier developed due to it at the P-N junction
8. Given below is the diagram of the P-N junction diode and depletion layer.

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