Question

Which side of diode is P and N?

Answer 1

In a diode, there are two sides: the **P-side** and the **N-side**.

1. **P-side (Positive side)**: This side is doped with acceptor impurities, which create "holes" (positive charge carriers). In silicon diodes, this side typically has a higher concentration of holes.

2. **N-side (Negative side)**: This side is doped with donor impurities, which add extra electrons (negative charge carriers) to the material. This side has a higher concentration of electrons.

When a diode is connected in a circuit, it allows current to flow from the P-side to the N-side when forward-biased (P-side connected to a higher voltage than the N-side) and blocks current in the reverse direction.

In summary:
- **P-side**: Anode (positive terminal)
- **N-side**: Cathode (negative terminal)

You can identify the P-side and N-side by looking for a small line or marking on the diode casing, which usually indicates the cathode (N-side).

Answer 2

A diode is a semiconductor device that allows current to flow in one direction but not the other. It has two distinct regions: the P-type (positive) region and the N-type (negative) region.

### P-Type Region
- **Composition**: The P-type semiconductor is created by doping pure silicon (or another semiconductor) with elements that have fewer valence electrons, such as boron. This creates "holes" (places where an electron is missing), making it positively charged.
- **Symbol**: The P-side of the diode is usually marked with a **positive sign (+)** or is often referred to as the **anode**.

### N-Type Region
- **Composition**: The N-type semiconductor is formed by doping with elements that have more valence electrons, such as phosphorus. This adds extra electrons, making it negatively charged.
- **Symbol**: The N-side is marked with a **negative sign (−)** and is known as the **cathode**.

### Connection and Operation
When you connect a diode in a circuit:
- **Forward Bias**: If the P-side (anode) is connected to a higher voltage than the N-side (cathode), the diode is forward-biased. Current can flow through the diode.
- **Reverse Bias**: If the N-side is connected to a higher voltage than the P-side, the diode is reverse-biased. In this case, the diode prevents current from flowing.

### Diagram Representation
In circuit diagrams, a diode is represented by a triangle pointing towards a line:
- The triangle's point represents the **anode** (P-side).
- The line represents the **cathode** (N-side).

### Summary
- **P-side (Anode)**: Marked with (+), allows current to enter.
- **N-side (Cathode)**: Marked with (−), allows current to exit.

Understanding these distinctions is crucial for using diodes effectively in circuits, as they dictate how the device will behave in various configurations.