why impurity doped silicon is a semi conductor.....?explain in a basic way?

Silicon forms 4 covalent bonds, two types of impurities can be added to Silicon, for example, Boron can be added or Phosphorus can be added. We know that. Boron forms three bonds and Phosphorus forms 5 bonds. When these elements are added to Silicon, they form bonds with the neighbouring Silicon atoms. When Silicon forms 3 bonds with Boron, it will result in an electron deficient bond and will create a hole. These holes can move through crystal like positive charge giving rise to electrical conductivity. Similarly, when Silicon forms 4 bonds with Phosphorus, one electron of Phosphorus atoms will remain unbonded, due to which it becomes delocalized and contributes to electrical conductivity.

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