Question

Differentiate between diffusion and drift current. Explain their role in p-n junction formation.

Hint:

Diffusion: concentration gradient; Drift: electric field

Answer 1

Diffusion Current: Movement of charge carriers from high to low concentration due to concentration gradient. In a p-n junction, electrons diffuse from n to p-side, holes from p to n-side. Creates depletion region and built-in electric field. Drift Current: Movement of charge carriers due to an electric field. In a p-n junction, the field in the depletion region causes electrons to drift to the n-side and holes to the p-side, counteracting diffusion. P-N Junction Formation: Initially, diffusion dominates, creating the depletion region. The depletion region creates an electric field, leading to drift current. Dynamic equilibrium is reached when drift current balances diffusion current.