Question

In what way is the electrical conductivity of a crystal affected by doping?

Answer 1

1. Doping increases the electrical conductivity of a crystal by introducing impurity atoms that create additional charge carriers.
2. In a pure semiconductor, the number of free electrons or holes is very limited, so its conductivity is low.
3. When a crystal is doped with an impurity of higher or lower valency, it either donates extra electrons (n-type doping) or creates holes by accepting electrons (p-type doping).
4. These free electrons or holes act as charge carriers and enhance the crystal’s ability to conduct electricity.
5. In the case of ionic crystals, doping with ions of different valency creates vacancies or interstitial defects, which allow ions to move more freely, thus increasing ionic conductivity.