For extrinsic semiconductors, when doping level is increased,

Options

A. Fermi-level of p-type semiconductor will go upward and Fermi-level of n-type semiconductors will go downward.
B. Fermi-level of p-type semiconductors will go downward and Fermi-level of n-type semiconductor will go upward.
C. Fermi-level of both p-type and n-type semiconductros will go upward for `T gt T_(F)` K and downward for `T lt T_(F)` K, where `T_(F)` is Fermi temperature.
D. Fermi-level of p and n-type semiconductors will not be affected.

Answer

To solve the question regarding the behavior of the Fermi energy level in extrinsic semiconductors when the doping level is increased, we will analyze the situation step by step.

### Step-by-Step Solution:

1. **Understanding Fermi Level**:
- The Fermi level is defined as the energy level at which the probability of finding an electron is exactly 1/2. In semiconductors, it indicates the energy state at which the occupancy of electrons changes from likely to unlikely.

2. **Intrinsic vs. Extrinsic Semiconductors**:
- In intrinsic semiconductors, the concentration of electrons and holes is equal, and the Fermi level lies in the middle of the band gap (between the conduction band and valence band).
- In extrinsic semiconductors, doping introduces additional charge carriers. There are two types: n-type (more electrons) and p-type (more holes).

3. **Behavior of Fermi Level in n-type Semiconductors**:
- In n-type semiconductors, when the doping level (electron concentration) is increased, the Fermi level shifts closer to the conduction band. This is because the increase in electron concentration raises the probability of finding electrons in the conduction band.

4. **Behavior of Fermi Level in p-type Semiconductors**:
- In p-type semiconductors, when the doping level (hole concentration) is increased, the Fermi level shifts closer to the valence band. This is due to the increase in hole concentration, which raises the probability of finding holes in the valence band.

5. **Conclusion**:
- As the doping level increases:
- The Fermi level in n-type semiconductors moves upward (closer to the conduction band).
- The Fermi level in p-type semiconductors moves downward (closer to the valence band).

6. **Evaluating Options**:
- Based on the analysis:
- The correct statement is that the Fermi level of the p-type semiconductor will go downward, and the Fermi level of the n-type semiconductor will go upward.

### Final Answer:
The correct option is that the Fermi level of the p-type semiconductor will go downward, and the Fermi level of the n-type semiconductor will go upward.

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