Overview
Pure silicon is a poor conductor. Doping involves adding small amounts of other elements to create an excess of charge carriers, either electrons (N-type) or 'holes' (P-type).
Doping Agents
- N-type Doping: Adding elements with five valence electrons (like Phosphorus or Arsenic) to provide extra electrons.
- P-type Doping: Adding elements with three valence electrons (like Boron) to create 'holes' (missing electrons).
Methods
- Ion Implantation: Accelerating ions into the wafer surface at high speeds.
- Diffusion: Heating the wafer in the presence of dopant gases.
Importance
The junction between P-type and N-type materials (P-N junction) is the fundamental building block of diodes and transistors.