Consider the following statements: 1. Fermi level in a p-type semiconductor lies close to the top of the valence band. 2. The forbidden energy in Germanium at 0 K is exactly 0.78 eV. 3. When a p-n junction is reverse biased, then electrons and holes move away from the junction. Which of these statements are correct?

Consider the following statements: 1. Fermi level in a p-type semiconductor lies close to the top of the valence band. 2. The forbidden energy in Germanium at 0 K is exactly 0.78 eV. 3. When a p-n junction is reverse biased, then electrons and holes move away from the junction. Which of these statements are correct? Correct Answer 1, 2, and 3

Fermi level:

The Fermi level is the energy separating occupied states of the valence band from empty states of the conduction band at the temperature T=0 K.

Fermi energy level in a p-type semiconductor:

For a p-type semiconductor, there are more holes in the valence band than there are electrons in the conduction band.

This implies that the probability of finding an electron near the conduction band edge is smaller than the probability of finding a hole at the valence band edge.

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Therefore, the Fermi level is closer to the valence band in a p-type semiconductor.

Forbidden energy gap:

It is nothing but the difference between the conduction energy band and valence energy band

For Germanium, the forbidden energy gap is 0.78 eV.

P-N diode:

A p-n diode is a two-terminal semiconductor device that

• Allows the current in only one direction (forward biasing)
• Blocks the current in the opposite direction (reverse biased).

Reverse bias:

When a p-n junction is reversed biased

• The negative terminal of the battery attracts the free holes in the p-type towards itself
• The positive terminal attracts the free electrons in the n-type towards itself.
• Hence, the electrons and the holes move away from the junction
• Due to this, the depletion width as well as the potential barrier are increased.