The potential barrier of a P-N junction diode is 50 meV, When an electron having energy 400 meV travels from N to P, after crossing the junction the energy of the electron is

Options

A. 450 me V
B. 350 meV
C. 400 me V
D. 300 meV

Answer

To solve the problem, we need to determine the energy of an electron after it crosses a P-N junction diode, given its initial energy and the potential barrier it must overcome.

### Step-by-Step Solution:

1. **Identify the Initial Energy of the Electron**:
- The electron has an initial energy of 400 meV.

2. **Identify the Potential Barrier**:
- The potential barrier of the P-N junction is given as 50 meV. This is the energy that the electron must overcome to cross from the N-type side to the P-type side.

3. **Calculate the Energy Loss**:
- When the electron crosses the junction, it loses energy equal to the potential barrier. Therefore, the energy lost by the electron while crossing the junction is 50 meV.

4. **Calculate the Remaining Energy**:
- To find the remaining energy of the electron after crossing the junction, we subtract the energy lost from the initial energy:
\[ \text{Remaining Energy} = \text{Initial Energy} - \text{Energy Lost} \]
\[ \text{Remaining Energy} = 400 \text{ meV} - 50 \text{ meV} = 350 \text{ meV} \]

5. **Conclusion**:
- After crossing the junction, the energy of the electron is 350 meV.

### Final Answer:
The energy of the electron after crossing the junction is **350 meV**.