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 follow these steps:

### Step 1: Understand the concept of n-type semiconductors
N-type semiconductors are created by doping a pure semiconductor (like silicon) with donor impurities (like phosphorus). These donor atoms provide extra electrons that contribute to electrical conduction.

**Hint**: Remember that in n-type semiconductors, the majority charge carriers are electrons contributed by donor atoms.

### Step 2: Analyze the filling of donor states
When we say that "all donor states are filled," it means that all available energy states provided by the donor atoms are occupied by electrons. This typically occurs at low temperatures or when the doping concentration is high.

**Hint**: Consider what happens to charge carriers when all available states are occupied.

### Step 3: Determine the charge density in filled donor states
When all donor states are filled, the electrons in these states contribute to the net charge density. Since each filled donor state corresponds to an electron, the charge density becomes significant.

**Hint**: Think about how the presence of electrons in filled states affects the overall charge density.

### Step 4: Evaluate the options given in the question
The question provides options: 1, greater than 1, or 0. Since we established that the filled donor states contribute electrons to the charge density, we can conclude that the charge density is indeed greater than 1.

**Hint**: Compare the implications of each option with your understanding of charge density in filled states.

### Conclusion
Therefore, when all donor states are filled in an n-type semiconductor, the net charge density in the donor states becomes greater than 1.

**Final Answer**: The net charge density in the donor states becomes greater than 1.

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