Diffusion and Drift Currents:
- Diffusion Current: A concentration gradient at a p-n junction causes electrons from the n-region to move to the p-region and holes from the p-region to move to the n-region. This charge carrier movement creates a diffusion current.
- Drift Current: The diffusion of carriers establishes an electric field across the junction, creating a depletion region. This field propels minority carriers in opposing directions, producing a drift current.
At equilibrium, the drift current (driven by the electric field) precisely counterbalances the diffusion current (driven by the carrier concentration gradient).