MHT CET Medical202622 April 2026Evening ShiftPhysicsSemiconductorsActual
The depletion region of a p-n junction is formed due to
Options
- Adrift of majority carriers under the influence of an applied electric field.
- Bthermal energy exciting electrons from the p-side to the n-side.
- Cdiffusion of majority carriers across the junction immediately after formation, leaving behind fixed immobile
- Dthe physical removal of material at the junction interface during manufacturing
Correct answer
C. diffusion of majority carriers across the junction immediately after formation, leaving behind fixed immobile
Step-by-step solution
When a p-n junction is formed, there is a concentration gradient of charge carriers across the junction. Due to this gradient, majority carriers diffuse across the junction. Holes diffuse from the p-side to the n-side, and electrons diffuse from the n-side to the p-side. As these mobile charge carriers cross the junction, they leave behind uncompensated, fixed immobile ions (negative acceptor ions on the p-side and positive donor ions on the n-side). This region near the junction, which is depleted of mobile charge