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

Options

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

Answer

To solve the problem, we need to determine the energy of an electron after it crosses the potential barrier of a P-N junction diode. Here are the steps to arrive at the solution:

### Step-by-Step Solution:

1. **Identify the Given Values:**
- The potential barrier (V) of the P-N junction diode is given as 50 meV (milli-electron volts).
- The initial energy (E_initial) of the electron is given as 400 meV.

2. **Understand the Concept:**
- When an electron crosses the potential barrier of a P-N junction, its energy decreases by the amount of the potential barrier. This is because part of its energy is used to overcome the barrier.

3. **Apply the Energy Conservation Principle:**
- The final energy (E_final) of the electron after crossing the junction can be calculated using the formula:
\[ E_{final} = E_{initial} - V \]
- Here, \(E_{initial}\) is the initial energy of the electron, and \(V\) is the potential barrier.

4. **Substitute the Values:**
- Substitute the given values into the equation:
\[ E_{final} = 400 \, \text{meV} - 50 \, \text{meV} \]

5. **Calculate the Final Energy:**
- Perform the subtraction:
\[ E_{final} = 350 \, \text{meV} \]

6. **Conclusion:**
- The energy of the electron after crossing the junction is 350 meV.

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

---