MAKING A DIODE:
Now we’ll see how the above described two types are used to manufacture a diode. We have the p-type and n-type semiconductors as follow:
Now we combine the two types of materials as follow and we have to observe what would happen when we combine the two:
When we combine the two types of material, the holes of p-type material and electrons of n-type start recombining as there is a force of attraction between them. This is also called diffusion of charges. Diffusion is defined as movement of charges from HIGH concentration to LOW concentration. We have high concentration of electrons in n-type semiconductor and high concentration of holes in p-type semiconductors while there is low concentration of electrons in p-type semiconductor and high concentration of holes in n-type semiconductors. Due to this difference in concentration of charges, diffusion occurs. Hence electrons move from n-type to p-type and holes move from p-type to n-type. Due to this movement some of the electrons and holes recombine.
Due to this recombination of holes and electrons, a depletion region is generated near the junction. Depletion region is the region where no mobile charges exist (neither electrons nor holes, only fixed charges). As the recombination of charges continues, an opposite electric field is developed and recombination continues only till the opposite electric field becomes equal to the force of attraction.
Now when the electric field is generated, it opposes the flow of electrons from the n-type and it opposes the flow of holes from the p-type.