Question

Explain the formation of potential barriers in a p-n junction.

Answer 1

Hint: A p-n junction is a boundary between two semiconductor materials namely p-type and n-type semiconductor. The p type semiconductor has an excess of holes in the material and the n-type semiconductor has an excess of electrons in the semiconductor.

Complete step by step solution:
It is asked in the problem about the formation of potential barriers in a p-n junction. A grain boundary in the semiconductors will not allow the movement of the electrons and due to which we need to add impurity in the material and this process is known as doping. A doping process is the process in which we add a pentavalent impurity in the small part of the p-type semiconductor and then a small portion gets converted into p-type semiconductor and other gets converted into n-type semiconductor and now both the p-type and n-type semiconductor will be there in the same silicon material.

After the formation of the p-n junction there will be a phenomenon of diffusion and drift. The diffusion is the process in which the holes and the electrons will mix into each other and the drift is a phenomenon in which the charges collide into each other.

When the holes start to move towards the electrons then there is formation of the layer of electrons on the p-type and a layer of holes in the n-type side which forms a region known as depletion layer, this depletion layer is the cause of the formation potential barrier.

Note: The movement of charge inside the p-n junction is the reason behind the current flow in the circuit. The holes in the p-junction move towards the electrons in the n- junction and due to this there is formation of a layer known as deflection region.