A diode is a semiconductor device that allows current to flow in one direction while blocking it in the opposite direction. It consists of two regions:
1. **P-side (Positive Side)**:
- The P-side is doped with **acceptor impurities**, which creates a surplus of holes (positive charge carriers). This side is generally referred to as the **P-type** semiconductor.
- It has a higher concentration of holes compared to electrons.
2. **N-side (Negative Side)**:
- The N-side is doped with **donor impurities**, which results in a surplus of electrons (negative charge carriers). This side is known as the **N-type** semiconductor.
- It has a higher concentration of electrons compared to holes.
When a voltage is applied across a diode, if the P-side is connected to the positive terminal (forward bias), the diode allows current to flow. Conversely, if the P-side is connected to the negative terminal (reverse bias), the diode blocks current flow. This property of diodes makes them essential components in many electronic circuits, such as rectifiers, clamping circuits, and signal modulators.