In an intrinsic semiconductor, the fermi energy level lies

Options

A. nearer to valence band
B. nearer to conduction band
C. exactly at the middle of the forbidden energy gap
D. Cant' say

Answer

To determine where the Fermi energy level lies in an intrinsic semiconductor, we can follow these steps:

### Step 1: Understand the Concept of Intrinsic Semiconductor
An intrinsic semiconductor is a pure semiconductor material without any significant dopant species present. This means that the number of charge carriers (electrons and holes) is equal.

**Hint:** Recall that intrinsic means "pure" and does not involve any impurities or doping.

### Step 2: Define the Energy Bands
In semiconductors, there are two important energy bands: the valence band and the conduction band. The valence band is the energy band that is filled with electrons, while the conduction band is the energy band that is typically empty at absolute zero temperature.

**Hint:** Remember that the valence band is where electrons are bound to atoms, and the conduction band is where electrons can move freely.

### Step 3: Identify the Forbidden Energy Gap
The forbidden energy gap (or band gap) is the energy difference between the top of the valence band and the bottom of the conduction band. In intrinsic semiconductors, this gap is significant because it determines the electrical properties of the material.

**Hint:** The forbidden gap is crucial for understanding how electrons transition between bands.

### Step 4: Determine the Position of the Fermi Level
In an intrinsic semiconductor, since the number of electrons is equal to the number of holes, the Fermi energy level (which indicates the probability of occupancy of energy states by electrons) lies exactly in the middle of the forbidden energy gap. This is because there is no bias towards either electrons or holes.

**Hint:** Think about the balance of charge carriers in intrinsic semiconductors when locating the Fermi level.

### Step 5: Conclusion
Thus, the Fermi energy level in an intrinsic semiconductor lies exactly at the middle of the forbidden energy gap between the conduction band and the valence band.

**Final Answer:** The Fermi energy level lies exactly at the middle of the forbidden energy gap.