Doping: Making Semiconductors Useful
Adding controlled impurities
What doping means
Doping is the deliberate addition of small amounts of impurity atoms to a semiconductor to change its electrical properties. Even a tiny amount of dopant can dramatically increase conductivity.
n-type and p-type
If the dopant adds extra electrons, the semiconductor is called n-type. If the dopant creates extra holes, it is called p-type.
n-type vs p-type semiconductors
n-type
- Majority carriers are electrons
- Created by donor dopants
p-type
- Majority carriers are holes
- Created by acceptor dopants
Tiny changes, big effects
Doping works because the crystal structure is sensitive to the number of available charge carriers.
Common doping ideas
| Type | Main carrier | Simple description |
|---|---|---|
| n-type | Electrons | Extra electrons are available |
| p-type | Holes | Extra missing electrons behave as positive carriers |
What does doping do to a semiconductor?
Doping is used to control conductivity and carrier type.
Correct answer: It intentionally changes electrical behavior
What type of semiconductor has holes as the majority carriers?
P-type semiconductors are hole-rich.
Correct answer: p-type
In n-type material, the majority carriers are usually:
n-type doping increases the number of available electrons.
Correct answer: Electrons