Question

Explain briefly the formation of diffusion current and drift current in a p-n junction diode.

Answer 1

Diffusion and Drift Currents:
- Diffusion Current: When a p-n junction is formed, due to concentration gradient, electrons from n-region diffuse to p-region and holes from p-region diffuse to n-region. This movement of charge carriers generates a diffusion current.
- Drift Current: As carriers diffuse, an electric field is established across the junction, forming a depletion region. This field drives minority carriers in opposite directions, resulting in a drift current.
At equilibrium, the diffusion current (due to carrier concentration gradient) is exactly balanced by the drift current (due to the electric field).