Question

The process that occur during formation of a $p-n$ junction is

• A. diffusion
• B. doping
• C. drift
• D. depletion

Answer 1

Answer: (A), (C)

The correct options are
A diffusion
C drift

During the formation of the p-n junction, the concentration of holes on p-side is more and concentration of electrons on n-side is more. As a result of this concentration gradient, electrons diffuse from n to p side and holed diffuse from p to n-side. This is called diffusion.
Drift: Because of potential barriers across the junction, an electric field will be set up across the junction which exerts a force on electrons in p-region to move towards n-side and force on holes in n-region to move towards p-side. As a result holes from n to p drift and electrons drift from p to n side. This constitutes drift current.