Explain the two processes involved in the formation of a p-n junction diode. Hence, define the term 'barrier potential'.

Explanation

### Step-by-Step Solution:

1. **Understanding the P-N Junction**:
A p-n junction diode is formed by joining p-type and n-type semiconductors. The p-type semiconductor has an abundance of holes (positive charge carriers), while the n-type semiconductor has an abundance of electrons (negative charge carriers).

2. **Process of Diffusion**:
- When the p-type and n-type materials are brought together, the electrons from the n-type region begin to diffuse into the p-type region. This occurs because of the concentration gradient; electrons move from an area of high concentration (n-type) to an area of low concentration (p-type).
- Simultaneously, holes from the p-type region diffuse into the n-type region. This is also driven by the concentration gradient.
...