Question

For a forward biased p-n junction diode, which one of the following energy-band diagrams is correct? (\( \epsilon_F \) is the Fermi energy) 

• A. A
• B. B
• C. C
• D. D

Hint:

In forward bias, the Fermi levels in p-type and n-type materials align closer to the conduction band and valence band, respectively.

Answer 1

The Correct Option is A

Step 1: Understanding the forward bias of a p-n junction.
In a forward biased p-n junction diode, the p-type side is connected to the positive terminal and the n-type side is connected to the negative terminal. This reduces the potential barrier, allowing current to flow. The Fermi level (\( \epsilon_F \)) moves closer to the conduction band in the n-type material and closer to the valence band in the p-type material.
Step 2: Identifying the correct diagram.
Option (A) shows the energy bands with the correct behavior for a forward biased p-n junction. The Fermi energy levels are shifted as expected in forward bias, and the conduction and valence bands are aligned correctly.
Step 3: Conclusion.
Thus, the correct energy-band diagram for a forward biased p-n junction diode is shown in option (A).