Question

Initially, during the formation of a p-n junction:

• A. Diffusion current is large and drift current is small.
• B. Diffusion current is small and drift current is large.
• C. Both the diffusion and the drift currents are large.
• D. Both the diffusion and the drift currents are small.

Hint:

In a p-n junction, diffusion current dominates initially, but as the depletion region builds up, drift current increases to balance it.

Answer 1

The Correct Option is A

Initial p-n Junction Current Dynamics
- At the moment of p-n junction formation, a significant concentration difference of charge carriers exists between the p and n sides.
- This disparity drives a substantial diffusion current, as electrons from the n-region and holes from the p-region migrate across the junction.
- The diffusion process simultaneously establishes a depletion region, which in turn generates an internal electric field.
- This electric field then induces a minor drift current by directing minority carriers in the reverse direction.
- Equilibrium is reached when the diffusion current and drift current equalize.
Consequently, during p-n junction formation, the diffusion current is dominant while the drift current is negligible.