In a p-n junction, a potential barrier of 250 meV exists across the junction. A hole with a kinetic energy of 300 meV approaches the junction. Find the kinetic energy of the hole when it crosses the junction if the hole approached the junction from the n - side

Options

A. 500 meV
B. 550 meV
C. 5000 meV
D. 55 meV

Answer

To solve the problem, we need to analyze the situation of a hole approaching a p-n junction from the n-side. The hole has an initial kinetic energy and must overcome a potential barrier to cross the junction. Let's break down the solution step by step.

### Step-by-Step Solution:

1. **Identify Given Values:**
- Potential barrier (V) = 250 meV
- Initial kinetic energy of the hole (K_initial) = 300 meV

2. **Understand the Concept:**
- When the hole approaches the p-n junction, it has to overcome the potential barrier. If it has enough kinetic energy, it can cross the junction.

3. **Calculate the Kinetic Energy After Crossing the Junction:**
- The kinetic energy of the hole after crossing the junction can be calculated using the formula:
\[ K_{final} = K_{initial} + V \]
- Here, \( K_{final} \) is the kinetic energy after crossing the junction, \( K_{initial} \) is the initial kinetic energy, and \( V \) is the potential barrier.

4. **Substitute the Values:**
- Substitute the known values into the equation:
\[ K_{final} = 300 \, \text{meV} + 250 \, \text{meV} \]

5. **Perform the Calculation:**
- Calculate \( K_{final} \):
\[ K_{final} = 300 + 250 = 550 \, \text{meV} \]

6. **Conclusion:**
- The kinetic energy of the hole when it crosses the junction is 550 meV.

### Final Answer:
The kinetic energy of the hole when it crosses the junction is **550 meV**.