Understanding Semiconductors | Generated by AI
This tutorial explains the basics of how semiconductors function, focusing on silicon and the creation of a diode.
1. Silicon Structure and Conductivity
- Pure silicon is a poor conductor of electricity because its electrons are tightly bound in covalent bonds.
- To make silicon conductive, impurities are added in a process called doping.
2. Doping with Phosphorus (N-type Semiconductor)
- Adding phosphorus, which has an extra electron compared to silicon, introduces free electrons into the silicon structure.
- These free electrons can move around, allowing the silicon to conduct electricity.
- Since the charge carriers are negatively charged electrons, this is called an N-type semiconductor.
3. Doping with Boron (P-type Semiconductor)
- Adding boron, which has one fewer electron than silicon, creates “holes” where electrons are missing.
- Other electrons can fill these holes, making it appear as though the positively charged “holes” are moving, which facilitates conductivity.
- Since the charge carriers are these positively charged holes, this is called a P-type semiconductor.
4. The PN Junction
- When N-type and P-type semiconductor materials are joined together, electrons from the N-type material move to fill the holes in the P-type material at the boundary.
- This creates a region at the junction with a lack of free charge carriers (both electrons and holes), known as the depletion region.
5. Diode Function
- A PN junction acts as a diode, allowing electric current to flow in primarily one direction.
- When a voltage is applied with the negative terminal connected to the N-type and the positive terminal to the P-type (forward bias), current flows once the voltage is sufficient to overcome the depletion region.
- When the voltage is reversed (reverse bias), with the positive terminal on the N-type and the negative on the P-type, the depletion region widens, preventing current flow.
This outline provides a foundational understanding of how doping creates N-type and P-type semiconductors and how their combination in a PN junction forms a diode that allows for one-way electrical current flow.
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