In n-type semiconductor when when all donor states are filled, then the net charge density in the donor states becomes

Options

A. 1
B. gt 1
C. lt 1, but not zero
D. zero

Explanation

To solve the question regarding the net charge density in the donor states of an n-type semiconductor when all donor states are filled, we can break down the solution into the following steps:

### Step 1: Understand the Concept of n-Type Semiconductors
In n-type semiconductors, donor atoms are added to the intrinsic semiconductor material. These donor atoms provide extra electrons, which are free to move and contribute to electrical conduction.

**Hint:** Remember that n-type semiconductors have extra electrons due to the presence of donor impurities.

### Step 2: Identify the Role of Donor States
Donor states are energy levels introduced by the donor atoms within the band gap of the semiconductor. When these states are filled, it means that all available donor electrons are now present in the conduction band.

**Hint:** Donor states are crucial for understanding how charge carriers are introduced in n-type semiconductors.

### Step 3: Analyze the Situation When All Donor States Are Filled
When all donor states are filled, the number of electrons in the conduction band increases. This means that the charge density associated with these donor states is also increased.

**Hint:** Think about how filling donor states affects the overall electron concentration in the semiconductor.

### Step 4: Determine the Net Charge Density
The net charge density in the donor states will be greater than one because each filled donor state contributes to the overall charge density. Therefore, when all donor states are filled, the net charge density is greater than one.

**Hint:** Consider the relationship between the number of filled states and the resulting charge density.

### Step 5: Select the Correct Option
Based on the analysis, the correct option is that the net charge density in the donor states becomes greater than one.

**Hint:** Compare your conclusion with the options provided to ensure you select the correct one.

### Final Conclusion
The net charge density in the donor states of an n-type semiconductor, when all donor states are filled, is greater than one. Thus, the correct answer is the second option.

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