Question

The depletion region of a p-n junction is formed due to

• A. drift of majority carriers under the influence of an applied electric field.
• B. thermal energy exciting electrons from the p-side to the n-side.
• C. diffusion of majority carriers across the junction immediately after formation, leaving behind fixed immobile ions.
• D. the physical removal of material at the junction interface during manufacturing

Hint:

Majority carriers diffuse across the junction at the start and leave fixed ions behind, forming the depletion region.

Answer 1

The Correct Option is C

Step 1: Compare the options
Drift under an applied field and thermal excitation are not the origin of the region, and nothing is physically removed during manufacturing.

Step 2: Why the other options fail
Option (A) mentions an applied field, but the region exists even with no bias. Options (B) and (D) are not the physical cause.

Step 3: Answer
Only option (C) explains the formation of the depletion layer.

Final Answer:
Option (C) is correct. \[ \boxed{\text{(C) }\text{diffusion of majority carriers across the junction immediately after formation, leaving behind fixed immobile ions.}} \]